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NNadir

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Member since: 2002
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Electrolytic reduction of carbon dioxide to formate using low over-voltages.

Here's a fun paper: Highly Selective Reduction of CO2 to Formate at Low Overpotentials Achieved by a Mesoporous Tin Oxide Electrocatalyst (Rahman Daiyan, Xunyu Lu*, Wibawa Hendra Saputera, Yun Hau Ng , and Rose Amal* ACS Sustainable Chem. Eng., 2018, 6 (2), pp 1670–1679)

Let me tell you something: Anyone with a name like Wibawa Hendra Saputera is definitely cooler than I will ever be, probably cooler than you'll ever be too.

Here's the introduction to the paper, what it's about:

Rising level of CO2 accumulation in the atmosphere has attracted considerable research interest in technologies capable of CO2 capture, storage, and conversion.(1-3) The electrochemical reduction of CO2 into high-value liquid organic products could be of vital importance to mitigate this issue.(4, 5) The direct conversion of CO2 to liquid fuel using renewable energy, which can readily be integrated with the current infrastructure, will help realize the creation of a sustainable cycle of carbon-based fuel that will promote zero net CO2 emissions.(6-10) Despite initial promising findings, significant progress is required in improving the production rate, efficiency, stability, and cost to make this technology realistic for large-scale utilization.(7, 11)

The current benchmarking electrocatalysts for CO2RR to formate (HCOO–) are sp group metals, notably, Pb, In, and Sn.(12-19) Among the high-performing materials, Sn-based catalysts are especially favored due to their relative low cost, abundance, and nontoxic properties, compared to Pb and In catalysts.(20) Sn catalysts however exhibit certain characteristics, for instance, the local chemical structure of Sn is shown to play a major role in CO2RR, as the bulk Sn foils are reported to have inconsistent formate Faradaic efficiency (FEHCOO–) at a wide range of potentials.(16, 21) To address such discrepancy in catalytic performances, numerous studies on the effect of electrolyte, pH, morphology, and catalyst deactivation for CO2RR with Sn-foil-based catalysts have been undertaken.(22-25) In spite of the insights and understanding into the mechanisms obtained by such studies, Sn-foil-based catalysts still require large overpotentials to attain high values of FEHCOO–. For example, three-dimensional Sn foam grown on Sn foil catalysts require a large applied potential of −1.3 V (vs RHE, applies for all potentials mentioned in this study) to achieve a FEHCOO– of 90%.(26) Similarly, the heat-treated Sn dendrite electrodeposited on Sn foil is also reported to convert CO2 to formate with a moderate FEHCOO– of 71% but this is also done at a large negative applied potential of −1.35 V.(22)


With all due deference to Wibara, this statement is a little off:

The direct conversion of CO2 to liquid fuel using renewable energy, which can readily be integrated with the current infrastructure, will help realize...


The current infrastructure contains very little so called "renewable energy;" overall the fraction of fossil fuels representing world energy portfolios is rising, not falling. In 2000, 80% of world energy came from dangerous fossil fuels. In 2016 (the latest data available) 81% of world energy came from dangerous fossil fuels.

Capturing carbon dioxide using electrical infrastructure that is almost entirely fossil fuel based is simply a perpetual motion machine.

But in theory, if not in practice, clean electricity is potentially available, albeit not from so called "renewable energy.'

No matter.

Some cool pictures of how they make their tin oxide mesoporous catalyst:



The caption:

Scheme 1. Fabrication of m-SnO2 Catalyst


A description of what's going on:

Mesoporous SnO2 was prepared by nanocasting method using KIT-6 as the hard template. KIT-6 was fabricated using an established method.(46) Briefly, 2 g of P123 (Pluronic P-123, Sigma-Aldrich, 99%) was dissolved in 72 mL of deionized water, followed by the addition of 2.5 mL of HCl. Then 2.47 mL of butanol was added dropwise and the mixture was stirred for a duration of 1 h at 35 °C. The solution was then transferred to a hydrothermal reactor and heated to 100 °C for 24 h. The solid product formed was then filtered and calcined at 600 °C for 5 h. To prepare mesoporous SnO2, 1.75 g of tin(IV) tetrachloride pentahydrate (SnCl4·5H2O, Sigma-Aldrich, 99%) was dissolved in 30 mL of ethanol. Then 0.6 g of KIT-6 was added and the mixture heated to 70 °C to evaporate ethanol. The sample was then calcined at 600 °C for 3 h. The impregnation and the calcination process were repeated again with two thirds of the Sn precursor used in the first step to complete the nanocasting process. The KIT-6 templates were then removed by washing the calcined powder twice in a hot 2 M NaOH solution. The resulting samples were collected by repeated centrifugation and washing with deionized water.


KIT-6 is mesoporous silica. I don't know how it's made, but I could look it up, but I'm short on time.

Here's some micrographs of the product anyway:



One of the interesting things about this paper is that the species being reduced is not carbon dioxide but rather the potassium bicarbonate salt. Electrolytic reduction of carbon dioxide is always limited by the low solubility of the gas in water, however the bicarbonate salt (which is made by the absorption of carbon dioxide into basic solutions) is very soluble.

The conclusion:

In summary, mesoporous SnO2 catalyst prepared by a simple and facile nanocasting method using a hard template was successfully employed as a novel electrocatalyst for the selective conversion of CO2 to HCOO–. The as-synthesized catalyst was capable of reducing CO2 to HCOO– with high efficiency and current density at low overpotentials and demonstrated a maximum Faradaic efficiency of 75% and a large current density of 10.8 mA cm–2 at an applied potential of −1.15 V. The results presented herein also demonstrated the high stability of the m-SnO2 electrode toward CO2RR, displaying a stable current density and Faradaic efficiency with no observable decay over 16 h of operation. The improved catalytic activity of the m-SnO2 electrode was ascribed to (i) preferential exposure of crystalline facets that provides sufficient active sites for CO2RR, (ii) significant presence of oxygen vacancy defects, and (iii) enhancement of CO2RR reaction kinetics due to reduced impedance and greater transport of reactants and facile dissipation of products through the large mesopores and well-dispersed catalyst.


Because we have been disinterested in their fate, future generations will need to clean up our carbon dioxide mess, and will need to do so with diminished resources, basically the trash we leave them.

In this regard, this is an interesting paper, since things like this may give them something to work with.

Have a nice evening.



Platinum Group Metal Extraction With Thermomorphic Ionic Liquids.

Many elements in the periodic table are subject to depletion from ores in near term; others in the long term.

Those subject in the short term include the "platinum group metals" - often referred to in the scientific literature as "PGM."

These are the elements, ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt).

The first three elements are common fission products that can be isolated from used nuclear fuels. Two of them, ruthenium and rhodium can be obtained in a non-radioactive form with a few decades of cooling; pure non-radioactive (but monoisotopic) Pd can be obtained from the decay of ruthenium-106, which has a half life a few days longer than a year.

Palladium that is isolated as a fission product will remain slightly radioactive for millions of years, owing to the long lived isotope Pd-107. From my perspective this does not mean it is not useful; it can be used as a catalyst (one of the big uses for palladium) in closed systems, and off line I've been considering it as a component of superalloys that would prove superior (higher melting) to the nickel based superalloys which plays a key role in many technologies, notably power generation. The longer the half-life of an isotope, the lower its specific activity; which is why bananas, radioactive because of the potassium they contain, don't kill you. K-40 has a half-life of billions of years.

In the next few years, rhodium will become more available from used nuclear fuels than it is from domestic ores.

It is thus with interest that I came across a paper in the literature today that mentions the extraction of these valuable elements from used nuclear fuels, this one: Significant Acceleration of PGMs Extraction with UCST-Type Thermomorphic Ionic Liquid at Elevated Temperature (Arai et al, ACS Sustainable Chem. Eng., 2018, 6 (2), pp 1555–1559.

The authors describe an "ionic liquid" that is useful for the extraction of the light PGM from used nuclear fuel, where they are considered problematic because they interfere with the bad idea of throwing the stuff in used nuclear fuel away, that is dumping it. (This is a bad idea because all of the components of used nuclear fuel are potentially very useful materials to have. We need more of the stuff, not less, even if as a culture we're generally too stupid to figure that out.)

Here's what they say in their introduction which I've just echoed above:

Ionic liquids (ILs) are commonly defined as organic salts which melt below 100 °C. They have unique properties, e.g., nonflammability, nonvolatility, high conductivity, and diversity of combinations of cations and anions. Specifically, it is possible to synthesize an IL with potential to extract metal ions (Mn+) due to introducing functional groups on either its cationic or anionic components. Because of these properties, the use of ILs as an extraction solvent for Mn+ has been frequently investigated.(1-8) The above characteristics make these extraction systems more environmentally friendly compared with the ordinary organic/aqueous biphasic systems. One of expected applications is treatment of radioactive wastes.(9) For example, platinum group metals (PGMs) like Ru, Rh, and Pd in the high-level liquid wastes are sometimes problematic in the vitrification process.(10, 11) Hence, removal of these PGMs is significantly required. In this context, we are investigating the potential of ILs in the PGMs extraction. A few ILs undergo a temperature-responsive behavior, which shows transition of miscibility of IL with an aqueous solution at a critical temperature.(12-17) Specifically, an IL consisting of N,N,N-trimethylglycinium (or betainium, [Hbet]+) and bis(trifluoromethylsulfonyl)amide ([Tf2N]− ) is hydrophobic enough to form an organic phase immiscible with water at room temperature, whereas these layers are completely miscible with each other above 55 °C, namely, the upper-critical solution temperature (UCST).(18-24) Therefore, [Hbet][Tf2N] (Figure 1(a)) is highly promising for an energy-saving extraction process because ultimately homogeneous mixing of the aqueous/IL biphasic system is facilitated only by heating.


Whenever I look at a new chemical these days, I try to reflect on its environmental fate based on my general knowledge of biochemistry and toxicology. This is why I'm horrified at the latest trend in "green" solar technology, the perovskites, because these are compounds of the toxic element lead, which is even worse than the use of the toxic element cadmium used in commercial solar cells being distributed today with complete disregard for all future generations and too much regard for fads.

Things with a shorter half-life in the environment are obviously better than those with longer half-lives. The best case is compounds that occur naturally.

As it happens, you contain ionic liquids and would die without them. This is choline, which is trimethylammonium ethanol amine chloride (or hydroxide), the cation being an peralkylated and reduced form of the amino acid glycine (albeit not biochemically synthesized from glycine, but rather from serine or methionine.)

Anyway...

Since used nuclear fuels have a very high energy to mass ratio, one should - with a little chemical sophistication - require trivial amounts of materials to process them, but this said, this has historically not been true, as we have learned from the interesting case of the Hanford tanks from the former weapons plutonium isolation plant in Washington State. (The interesting chemistry of these tanks is fascinating, by the way, but that's a topic for another day.)

Here is the structure of the ionic liquids that may prove useful for the extraction of PGM from used nuclear fuels:



The ion on the top left is betaine, a common constituent of plants that helps plant cells balance their osmotic pressure. The ion on the top right is dehydroxycholine; I'm not aware of its presence or lack of presence in living cells, but I image it's going to be metabolized much like either choline or betaine.

The ion on the bottom of both species is however, is bistrifluromethylsulfonyl imide. This is a derivative of triflate, a common reagent utilized as a protecting group in organic synthesis. Triflate is the salt of trifluorosulfonic acid, one of the more powerful acids in the world and regrettably, an acid that is extremely stable. It is therefore environmentally suspect, since it is likely to persist for a long time, rather like the problematic PFOS side product of the Teflon industry and the fabric protection industry, widely distributed, long lived and rather suspect as a potential carcinogen.

I would suspect that triflate might be subject to some radiological degradation, but a lot of radiation in the presence of lots of water would be required, which is why the stuff is good for processing nuclear fuels, but potentially problematic unless completely recovered and recycled.

Anyway, this ionic liquid is very good at the removal of PGMs not only from nuclear fuels, but from other materials from which they may need recovery, at least when they are heated in low concentrations of nitric acid. (PGM are very, very, very, very useful elements.)

A graphic from the paper:



The caption:

Figure 5. Dependence of the extraction efficiency (E%) of Mn+ on [HNO3] in HNO3(aq)–[Hbet][Tf2N] systems.


They may also be useful for partial separations from one another, given their differening distribution constants:



The caption:

Figure 6. Distribution ratio (D) of Ru(III), Rh(III), and Pd(II) as functions of (a) [[Hbet]+] in 0.3 M HNO3(aq)/[TMPA][Tf2N] and (b) [H+] in (H,Na)NO3(aq)/[Hbet][Tf2N] (total [NO3–]: 3.00 M). Initial condition: [Ru(III)] = 7 mM, [Rh(III)] = 3 mM, [Pd(II)] = 5 mM, T = 353 K.


The authors conclude thusly:

To answer what drives the extraction of inert PGMs from HNO3(aq) to the thermomorphic [Hbet][Tf2N] ionic liquid, we studied the distribution behavior of Ru(III) and Rh(III) at different temperatures as well as that of Pd(II), the labile PGM. As a result, the kinetics of the extraction reactions of the inert PGMs were successfully improved at elevated temperatures. Their interaction with [Hbet]+ to form extractable species is the rate-determining step, which has been successfully accelerated by convection heating. Thus, the extraction of these inert PGMs seems to be simply temperature controlled regardless of the heating methods like convection and microwave. The extraction mechanism of Ru(III), Rh(III), and Pd(II) in the current extraction system is concluded to follow the formation of the PGM:bet complexes to release H+ to the aqueous phase. Further detailed investigations are currently ongoing, for instance, separation from other Mn+, preparation and characterization of the extractable PGM:bet complexes, and stripping behavior of the extracted PGMs from [Hbet][Tf2N]. We wonder that the back-extraction kinetics would also be affected by the temperature.


The subtext of this is that despite public fear and ignorance, there are still some people intelligent enough to be figuring out what to do with used nuclear fuels. This can only be good for a future that may prove inhabited by wiser people than we have proved to be.

Have a nice day tomorrow.




Emily Carter Predicts Low Temperature Photodissociation of Nitrogen Gas Bonds.

Although nitrogen comprises about 78% of the planetary atmosphere, living things cannot utilize it in its native state, and until the early 20th century, all of the bioavailable nitrogen depended on nitrogen fixing bacteria, often (on land) in symbiotic association with legumes. The enzymes responsible are probably iron based biocatalysts. (cf. PNAS 2006 November, 103 (46) 17107-17112 (A thermophilic nitrogen fixing bacteria is also known (cf Science 15 Dec 2006:Vol. 314, Issue 5806, pp. 1783-1786 - it or a similar organism may have played a role in the evolution of life on earth.)

In its diatomic elemental form nitrogen is extremely non-reactive. In fact, many chemical reactions in the lab are conducted under pure nitrogen gas (or semi-pure nitrogen in which the other constituent is argon) because the gas is considered inert, a kind of honorary noble gas.

One of the most important industrial chemical reactions on which our food supply depends is the Haber-Bosch process for breaking the triple bond in N2 gas, which liberated humanity from dependence on legumes for nitrogen fixation. (There is no physical way world population today could subsist on biologically fixed nitrogen; without industrially fixed nitrogen easily more than half the people now living would need to starve to death.)

The energy for this reaction comes from the use of dangerous natural gas (reformed with water to give hydrogen gas). According to the USGS the world produced 140 million metric tons of ammonia in 2016. The thermodynamic limit for this reaction is on the order of 20.9 GJ/ton, as of 2000, according to Smil's famous book on the topic, the industrial process's energy requirement had been reduced from 100 GJ/ton (dangerous coal based) in 1920 to 26 GJ/ton by the year 2000 (dangerous natural gas based.) (Smil, Enriching the Earth, MIT Press, 2001, Appendix K, Page 244.) It is difficult to imagine that an industrial process operating in 2000 at 80% thermodynamic efficiency has improved by all that much, but even it were operating at 100% efficiency, it would still represent a significant amount of energy. At 26 GJ/ton the demand to make 140 million tons of ammonia would be around 3.6 exajoules.

For comparison sake, all the world's solar and wind plants combined, the subject of so much delusional cheering, according to the 2017 World Energy Outlook, table 2.2, page 79 produced 9.4 exajoules of energy (out of 576 exajoules overall.)

However, much of the energy associated with ammonia production involves both heat and pressure to overcome the thermodynamic barrier of breaking the nitrogen-nitrogen triple bond in nitrogen gas. This bond is one of the strongest chemical bonds known, having a strength of 941 kJ/mol, (225 kcal/mol). (cf: Chirik et al, Nature Chemistry volume 2, pages 30–35 (2010))

Thus it was with interest that I came across a note in my email referring to recent calculations by the Dean of Engineering at Princeton University, Emily Carter, and one of her students that show that it is possible, based on computational chemistry determinations to photochemically lower the activation energy for the dissociation of nitrogen-nitrogen bonds:

New process could slash energy demands of fertilizer, nitrogen-based chemicals.

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Dr. Carter is one of the foremost computational chemists in the world, a leader in the development of what is known as "orbital-free density functional theory," a method of calculations to direct the discovery of new materials, catalysts and other molecules. While this sort of thing is somewhat esoteric, it is nonetheless extremely important to science and technology, and thus to modern human life.

It is difficult to predict how world changing scientific discoveries will prove to be; many seem to be earth shattering, but afterwards encounter difficulties that prove industrially insurmountable or simply get lost for a lack of funding by people who hate science, like, say, um Trump, Ryan and their league of exceedingly stupid people.

Nonetheless this discovery predicting a gold nanoparticle based catalysis could prove to be very important. (Perhaps scientists in less declining countries than the United States could take it up.)

Dr. Carter's scientific paper is open sourced and is here: Prediction of a low-temperature N2 dissociation catalyst exploiting near-IR–to–visible light nanoplasmonics (Martirez and Carter, Sci. Adv. 2017;3: eaao4710 22 December 2017)

Have a pleasant Sunday.








Little Wing.

Diblock Fullerene Derivatives for Organic Solar Cells.

Just a few minutes ago, I posted a remark about indium tin oxide in this space, to excerpt it:

In cell phones, and in solar cells of the (CIGS) type, indium is in the form of ITO, indium tin oxide.

There are no pure ores of indium, and its solubility in ocean water is extremely low. It is a side product of the refining of zinc and a few other element ores.

In order to meet a requirement that we simply use indium that has already been isolated - the endless "we'll just recycle it" stuff that always ends up as a panacea statement whenever one makes a point that, for example, wind turbines and solar cells are not, in fact, "renewable" - it must be the case that 100% of the world's cell phones and 100% of its CIGS solar cells make it back to a recycling plant. Moreover indium, even if it is an essential component, is in low concentrations in these devices, and therefore one must invest considerable energy to recover it, not to mention using large amounts of materials, solvents, reagents, acids, bases, what have you.


A few minutes thereafter, just now, I came across a wonderful paper relevant to the general perception that solar cells will save the day even if they have not saved the day, are not saving the day - CO2 at Mauna Loa yesterday, January 29, 2081, was measured at 408.26 ppm - and, even if I'm swimming against the mainstream here, will not save the day.

But we have to try, people say, we have to try.

Here's the paper I just opened:

Amphiphilic Diblock Fullerene Derivatives as Cathode Interfacial Layers for Organic Solar Cells (Tu, Li, Li, Liu, Liu, ACS Appl. Mater. Interfaces, 2018, 10 (3), pp 2649–2657)

It's all about organic solar cells, which will of course, be green, green, green, green, because solar is sunlight and sunlight grows trees.

Some introductory text from the paper:

Because of the advantages of low cost, lightweight, flexibility, large-area fabrication, and semitransparency, organic solar cells (OSCs) have been a promising technology for clean and renewable energy conversion.(1-5) To improve the power conversion efficiency (PCE), much attention has been given on the interface control, material design, self-assembly of the donor and acceptor phases, and device fabrication.(6-8) In addition, the PCE of OSCs has reached over 13%.(9, 10) One of the strategies is to develop new donor or acceptor materials to enhance the short-circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF).(11, 12) On the other hand, approaches during the device fabrications, such as incorporation of additives, controlling the growth rate of films, and interface modifications, have also been well-studied and exhibited extremely important influences.(13, 14) The device geometry and interface properties are verified to be two main critical factors toward the preparation of high-performance OSCs...


Then there's some stuff about the work function of Zinc oxide, wonderful stuff too.

And then this:

In this work, we developed a new amphiphilic diblock fullerene derivative [6,6]-phenyl-C61-butyricacid-4-(9,9,9′,9′-tetrakis(3-bromopropyl)-9H,9′H-[2,2′-bifluoren]-7-yl)phenol-(N,N,N-trimethylpropan-1-aminium) bromide (C60-4TPB) with ammonium groups on the side chain of the fluorene block (Figure 1). This diblock molecule shows selected solubility and can support multilayer OSC structures by solution processing. Because of its rigid amphiphilic design, solvent annealing will be applied and expected to induce the self-assembly of the interface layer, which can help to investigate the influence of morphology in the interface layer on the performances of OSCs. The existence of large amount of fullerene in the cathode interface layer is expected to form multi-transmission channels for the electrons and to decrease the hole quenching at the cathode for the polymer: fullerene solar cells (Figure 1).


Fullerene, C60, was the subject of a huge amount of organic chemistry twenty or thirty years ago by all sorts of great organic chemists using very elegant syntheses involving cool cycloadditions and all kinds of other great stuff.

Eventually it was discovered - generating a Nobel Prize - not by synthesis but as common component of soot, specifically lampblack.

Nevertheless we can do all kinds of cool stuff with it now, apparently even make organic solar cells.

That's all great, but for me, I'll just go to the pictures from this paper.

Here's one:



The caption:

Figure 1. Chemical structures of the amphiphilic diblock fullerene derivative C60-4TPB and the structure of the inverted device.


That ITO at the bottom of the device, that's the indium tin oxide I talked about in my previous post and excerpted here.

There's silver on the top, and a layer of molybdenum trioxide as well. The PTB stuff is a C71 organic materials.

Here's the "green" chemistry for making the diblock fullerene:



Intermediate (e) is a bromotetraphenylene, in other words, a halotetraphenylene. Structurally it reminds me of two interesting sets of compounds that appear a great deal in the environmental literature.

One is the PCB's, which are halobiphenyls. These have made all of the fish in the Hudson River potentially carcinogenic to eat, since they are functionalized planar molecules that fit nicely into the minor groove of DNA and bond to it. They've done all sorts of things to remove PCB's, dumped by GE into the Hudson River as part of their manufacture of transformers and capacitors, dredging, pumping blah, blah, blah. Of course if you dredge, you need to need to dump the dredgings somewhere, and well, that's an expensive problem. (PCB's can be destroyed radiolytically, but nobody likes radioactive stuff.)

The second class of compounds of which this bromotetraphenylene reminds me is the brominated flame retardants, now banned in most countries but still found in all human (and most animal) flesh, in particularly the structurally close bromodiphenyl ethers, which are carcinogenic for the same reason, DNA grooves and planarity.

4-TPB has a 4-hydroxygroup, readily subject to oxidation to a quinone type system, conjugated with a planar tail, just a great system for forming DNA adducts.

Oxidization of aromatic rings is thought to be one reason that PAH's - another component of soot - is successful at forming DNA adducts that one can discover using high resolution mass in certain cancer cells.

For example, picked at random, here's an sample paper: Carcinogenic polycyclic aromatic hydrocarbon-DNA adducts and mechanism of action

The full synthetic process - an organic chemists wet dream with all kinds of wonderful solvents, separations, catalysts and chromatographic separations - is fully described in the supplemental information, which is, as always, open sourced.

If any of this sounds troubling, don't worry, be happy.

All solar chemistry is green, even when performed at a billion ton scale as we all hope it will be - well, as most of us hope with the exception of cranky old fat bald guys like me - because it's, um, "solar."

The conclusion of the paper is inspiring, even if some people can't get with the program and remain cynical:

In summary, an amphiphilic diblock fullerene derivative C60-4TPB has been developed and successfully employed with novel self-assembly properties by solvent annealing. Because of its interface modification properties, C60-4TPB can be applied as cathode interface layers between the ZnO and the active layers in the inverted OSCs to improve the interfacial compatibility between ZnO and the organic layer. Solvent annealing was carried out to increase the assembly of the fullerene block at the top surface of the C60-4TPB layer. The enriched C60 molecules were also expected to influence the distribution of PC71BM in the active layer and decrease the quenching of the hole at the cathode interface, resulting in an increased FF. For the device ITO/ZnO/C60-4TPB (0.5 mg/mL)/PTB7 : PC71BM/MoO3/Ag annealed by toluene solvent, an enhanced average PCE of 8.07% with a relatively long-term stable cathode interface was observed. The results demonstrated that the C60-4TPB layer is an ideal candidate to improve the photovoltaic performance of the inverted OSCs based on ZnO.


Again, don't worry, be happy. Everything will be wonderful in the grand solar renewable future. It must be true. I read about it on the internet.

Some people just don't get it.

We're saved.





A Review Article On the Utilization of Carbon Dioxide.

As I often repeat, the failure of humanity to address the destruction of the planetary atmosphere will require future generations, should they prove capable of restoring whatever is left to restore of this planet, will require the removal of carbon dioxide from air, possibly via its removal from seawater.

This is a huge thermodynamic, and therefore engineering and energy challenge. It will require future generations to produce more energy than we now consume profligately, and with zero interest in the waste this energy production involves.

Of course in dealing with cleaning up our waste, future generations will be belabored and not enriched, but it's clear we couldn't care less about them, so it's their problem.

In this sense we are all Republicans, whether we acknowledge it or not; we care only about ourselves and have no interest in the welfare of other people. In this case, when I refer to "other people," I am referring to people who are now infants or children, and their children and infants, that is, all future generations.

Of course, it is not enough simply to remove carbon dioxide from the air; one must also have a place to put it.

The "place to put it" has often been imagined with the endless proposals of waste dumps euphemistically called "sequestration," although the word "dump" is appropriate. The current waste dump is of course, the atmosphere.

It turns out that another means of dealing with carbon dioxide would be to utilize it, which is a proposal to make it something other than "waste." Carbon dioxide is a currently utilized product industrially, although its use currently is nothing like the quantities dumped into the atmospheric waste dump, an amount on the order of 35 billion tons per year.

I think about these things a lot, and this is why I was pleased to go through the recent issue of Chemical Reviews, which was about sustainable chemistry.

An aside:

Recently in this space, in a post to which this post is a follow up, a comment of Vaclav Smil's (I wish people would embrace his clear thinking about energy, if not necessarily accepting his conclusions) about how refining of steel requires coal - I would argue that it need not do so forever, as I will briefly allude to below - that I partially repeat:

As an old-fashioned scientist, I prefer hard engineering realities to all those interminably vacuous and poorly informed policy “debates” that feature energy self-sufficiency (even Saudis import!), sustainability (at what spatial and temporal scales?), stakeholders (are not we all, in a global economy?) and green economy (but are not we still burning some 9 billion tonnes of carbon annually?)...



To answer the part I have put in bold above, my own definition of sustainability, if clearly not that of my contemporaries, would be a statement that each generation leaves for subsequent generations a planet that will afford ecosystem of the planet more or less in the same state into which they were born, and will allow the members of future generations the same level life style - including the opportunity to appreciate the beauty of the natural world - that the generation leaving enjoyed.

And no, the construction of millions of wind turbines that will be rotting hulks 30 years after construction, and millions of solar cells that will be electronic waste in thirty years won't cut it, any more than spent fracking fields - on which the fantasy to the contrary has depended, is depending and will always depend - leaching radioactive and chemically contaminated flow back water for centuries will cut it.

The paper I will discuss is this one: Sustainable Conversion of Carbon Dioxide: An Integrated Review of Catalysis and Life Cycle Assessment (Leitner et al, Chem. Rev., 2018, 118 (2), pp 434–504)

The authors are German, and well they should consider this point, since the official and in my opinion extremely ignorant national German energy policy is to put lipstick on the pig of long term fossil fuel dependence which they are clearly interested in entrenching forever, or at least until every trace of fossil fuel waste that can be generated has been stuffed into the atmosphere and oceans, neither of which clearly can take it anymore without severe changes to their stability.

The paper's opening graphic, which I believe is accessible from the abstract is this one:



It is slightly inaccurate, since it seems to show a requirement for free isolated hydrogen, which is actually not necessary, although hydrogen might be present in many - maybe in most - schemes as a captive intermediate.

There are ways that carbon might be converted into products that do not depend on hydrogen, as I will describe briefly below.

"Life Cycle Analysis," "LCA," is an increasingly important discipline in evaluating the "sustainability" of a particular energy practice, but it is information dependent inasmuch as it depends on intimate knowledge of industrial processes. It is important to consider that it is also necessarily subjective.

For example it might matter to me if formerly pristine deserts are strewn with rotting metal thirty years from now as represented by abandoned wind farms, but it is not clear that if you establish the criteria as being "loss to human life" as being the only criteria that matters, the rotting metal abandoned wind farms will not be as important - although the production of the steel in them will have lead to losses of human life in the generation that built them because modern steel production always utilizes coke which is almost always made by heating coal.

Here is another graphic from the internal text of the paper that puts things in life cycle terms:



Here is the caption for that graphic:

Figure 3. Environmental impacts of CO2-based polyols compared to fossil-based polyols according to von der Assen and Bardow.117 The values are related to the fossil-based production of 1 kg of fossil-based polyol. The CO2-based polyols offer environmental impact reductions in all nine impact categories.


Reference 117, Life cycle assessment of polyols for polyurethane production using CO2 as feedstock: insights from an industrial case study (Barlow and Assen, Green Chem., 2014, 16, 3272 does not contain the graphic immediately above, although the abstract shows a graphic present in the paper itself shows propylene oxide reacting with carbon dioxide to give a polymer. (Not shown is the solvent, which is DMC, dimethyl carbonate, which can also be made from carbon dioxide, as the review article discusses at length.)

Reference 117 is about a polycarbonate, a type of plastic which in this case is utilized to produce another polymer, polyurethane, albeit using a product obtained from dangerous fossil fuels, toluene isocyanate. (cf Green Chem, 2016, 16, 1865)

Returning however to the graphic above, note that it is an octagonal representation with lines from each of the vertices to the center representing a "reference case" for an environmental impact, and that the "global warming" impact is merely reduced, by less than 20%, not eliminated.

In reference 117 the process is described as capturing carbon dioxide from lignite coal burned in Germany's lignite coal plant at Niederaussem which is not being phased out like Germany's nuclear plants - all to be phased out - that do not require fossil fuels and which do not dump fossil fuel waste into the atmosphere.

Moreover, it's not clear that the carbon dioxide to make the polymer will never be added to the atmosphere, and quite possibly the whole enterprise, as described, is lipstick on the coal pig.

This said, were the carbon dioxide obtained from the removal of carbon dioxide from the atmosphere by carbon dioxide free means - which in my view can only be represented by nuclear energy, the following graphic from the review, a representation of the "savings" (with respect to direct dangerous fossil fuel waste dumping) would have a different form:




To wit, the denominator in the unit for the ordinate would disappear, since no carbon dioxide would be produced to make the polymer. To the extent that the polymer were recycled (albeit requiring an investment of energy) it would be possible to entirely close the carbon dioxide cycle, or at least minimize by a factor of perhaps 90% as opposed to "less than 20%."

(Don't you love "percent talk?" I actually don't, since it's most often used, in particular in the misrepresentation of the solar and wind industries as significant - which they are not when compared to the rapidly increasing use of dangerous fossil fuels, to perpetuate a lie rather than to describe the truth.)

Now let's turn to some chemistry, with this graphic from the review:



Reaction set (a) is lipstick on the methane (dangerous natural gas) pig, and refers to the mistaken impression that hydrogen is a "green" or "clean" fuel. This reaction - and it's coal based analogue - is, by the way, the means with almost 99% of the hydrogen industrially produced on the planet, by reformation, and not by electrolysis, the stupid exercise on the Norwegian Island of Utsira notwithstanding.

Reaction (b) is the partial reversal of reaction (a) and is known as the "water gas shift" reaction.

Reaction (c) is part of the international pipe dream about the wind and solar industries; it is extremely thermodynamically inefficient and the dream of expanding it to meaningful levels using technologies that have never proved meaningful, solar and wind, is in fact simply a measure of denial as pernicious as the level of denial practiced by the idiots in the Republican party.

Reaction (d) is of some interest depending on whence the high temperatures required come; provided by nuclear means, they can significantly improve the thermodynamic nightmare of electrolysis; produced by the solar thermal day dream - that industrially is environmentally destructive and totally dependent on supplemental dangerous gas as well as exorbitant in cost - it's just more garbage thinking.

Reaction set (e) is however quite interesting if only represented by loose schematic, non-stoichiometric carbon dioxide and water splitting.

In the modern scientific literature, this set (e) is almost always described in terms of "solar thermal" schemes. These do not work and will not work for the simple reason that batch processes are always more expensive and always dirtier than continuous processes, a fact that should be familiar to any well educated chemical engineer.

Historically these processes were often described by nuclear systems, and the most famous thermochemical hydrogen cycle, the sulfur iodine cycle, was that which was pushed by the General Atomics company, a company that proposed to build HTGC reactors with a helium working fluid Brayton cycle which would, in theory cogenerate hydrogen by splitting water.

The sulfur iodine cycle is not represented by the series in equations (e), nor should it be, since reactions (e) can produce either hydrogen or carbon monoxide, the latter being utilized by the use of reactions in set (a) to produce hydrogen without dangerous fossil fuels.

The GA HTGC reactors proved to be economic failures, since the attempt to build them - a few were built but didn't operate all that long - was before its time: The successful production of sustainable refractories advanced in the 1960's and 1970s in connection with the Space Program as a side product of that noble enterprise.

It is worth noting by the way, the General Atomics is now the site of one of two research nuclear fuels reactors in the United States, the other being at the Princeton Plasma Physics lab outside of Princeton, NJ.

If fusion ever became a practical form of energy - I doubt it will be significant in the lifetime of anyone now living, any more than solar or wind energy will be - all the reactions in set (e) would be practically and moreover sustainably driven.

About CO, carbon monoxide: Methane is often incorrectly thought to be "clean burning" because it produces low particulates, lacking the carbon-carbon bonds found in the admittedly dirtier fuels petroleum and coal.

The oxidation of methane does not, however, only produce the dangerous fossil fuel waste carbon dioxde since it is almost always the case that the oxidation is incomplete, and one incomplete product of said oxidation is carbon monoxide. Indeed the industrial process for producing hydrogen does this deliberately, partially oxidize methane.

Carbon monoxide however is not thermodynamically stable at all temperatures, it in fact exists in equilibrium with pure elemental carbon and carbon dioxide. This is known as the Boudouard equilibrium:



The Boudouard equilibrium shows that it is possible to obtain carbon from carbon dioxide, should one split carbon dioxide by reactions like those in reaction series (e), isolate carbon monoxide resulting from it, and then drive the Boudouard equilibrium to carbon by removing carbon dioxide by simple thermally reversible chemical means.

One of the tools for producing steel is carbon, whether the steel is structural steel in skyscrapers, or cars, or bridges or for that matter the quixotic enterprise of building windmills that pass, inappropriately, for energy decency in these times.

Theoretically at least, it may not thus be true that in order to make steel, one needs to mine coal.

And to the extent that metal carbides are used as important materials, and to the extent that other carbon based materials like those highly involved in modern nanotechnologies for just one example they represent utilized carbon that is not in the atmosphere.

A great deal of the review article covers the preparation of motor fuels from carbon dioxide. These are in general dependent on generating hydrogen, although some of the work covers electrolytic means of reduction, for example the electrolytic reduction of carbon dioxide to methanol, formaldehyde, formic acid and even alkanes.

Hydrogenation produces - I suspect with far greater thermodynamic efficiency - fuels like DMC, dimethyl carbonate, and the wonder fuel dimethyl ether, which for my money is the best energy storage material possible, far superior to hydrogen itself.

By reactions like those in set (e) above, all of these things can be accomplished by nuclear energy.

Is this easy? No, it isn't. There's no reason to be as glib as the failed "solar will save us" and "wind will save us" nonsense rhetoirc one hears all the time.

However if we are having a sustainable world, we are a long way away, and as everything we've done has failed, it's to try another way.

Below are some additional graphics from the review, which, being a review article discussing other papers, may or may not be broadly applicable. It is worth noting that many publications do not discuss nuclear energy, because nuclear energy is subject to broad public, if ignorant, approbation, and public approbation and attitudes do in fact, rightly or wrongly, effect the issuance of the grant system that supports our science.

A big graphic of the water gas equilibrium:



This graphic refers to "DRM" or dry reforming of methane, in which the dangerous fossil fuel natural gas is oxidized using CO2 rather than oxygen, a half-assed approach to eliminating carbon dioxide waste, but still an improvement in the efficiency of its use.:




The caption:

Figure 6. Global warming impact (GWI) of two CO2-based pathways for CO (+ H2) production (cradle-to-gate): reverse water−gas shift (rWGS; Scheme 5b) and dry reforming of methane (DRM; Scheme 5a). The results are presented for 1 kg of CO and 0.216 kg of H2 (functional unit, FU). For each pathway, a scenario for 2020 and a best-case scenario are considered (Table 1) on the basis of the LCA data by Sternberg and Bardow.281 The CO2-based processes are compared to the fossil-based steam methane reforming (dashed line).


From my perspective, it is not enough to reduce carbon dioxide dumping, but it is essential to not dump it at all.

Here's a graphic representing the catalysts for "DRM:"



Here's a big blow up of the equations for metal based thermochemical carbon dioxide and water splitting. Metals included in these schemes are typically, if one wanders around the literature, iron, cerium, and (albeit not represented by the equations here, tin. There are other examples.




This graphic is a schematic of high temperature and low temperature electrolysis of water and carbon dioxide, performed in some cases synergistically.



This graphic refers to the production of the hydrogen storage compound formic acid, and regrettably refers to the use of dangerous fossil fuels, and is thus not a fossil fuel elimination scheme so much as a reduction scheme, and therefore in my personal view, not sustainable.



Some text from the review - there's lots of text - that describes an interesting and beautiful formic acid production scheme, albeit one that still needs work:

Recently, another piloting activity to validate a CO2-based formic acid process has been initiated by the company Reactwell.394,395 Their study is based on a process developed by the Leitner group396,397 in 2012 which allows the continuous hydrogenation of CO2 to pure formic acid in a biphasic system (Figure 10). In this concept, CO2 is used under supercritical conditions as the mobile phase and combined with an ionic liquid (IL) as the stationary phase containing the ruthenium catalyst and the nonvolatile base. Under these conditions, the supercritical phase carries both reagents efficiently into the IL phase where CO2 is hydrogenated to formic acid, which is in situ extracted and carried out of the reactor. Thermodynamically, the solvation of formic acid in the scCO2 (sc = supercritical) phase can be regarded as the driving force. Overall, this reaction system integrates the reaction and the separation in a single process unit. Under laboratory conditions, total turnover numbers remained limited due to high catalyst loadings, but excellent stable performance was achieved under continuous-flow conditions over 200 h.


Whatever the limitations of the schemes found in this review, if you can find access, the review is worth a read.

Have a pleasant Sunday evening.

Landmines in the Republican War on the Middle Class: Home Equity Loan Interest No Longer Deductible.

My accountant sent out a notice that if you have a home equity type loan on your home, you will no longer be able to deduct your interest.

The money raised on the backs of the middle class in this particular example will go into a slush fund for the Trumps, the Kushners, the Wynns, the people who own Paul Ryan and Mitch McConnel and other people who couldn't care less about how you, for one example, put your kids through college.

If you're in this situation, you're going to have to pay your bank to refinance.

It's a word of warning. It could cost you tens of thousands of dollars if you're in this situation.

The Energy Requirement of Metal Processing and the Nuclear Option.

For my money, the most interesting, and possibly the most challenging thinker on the topic of energy in our age is Vaclav Smil.

I first became aware of him when I was thinking about the subject of catalytic nitrogen fixation and kept finding references in scientific papers on modern development of catalysts to his outstanding book on the history and development of this process on which our food supply is now entirely dependent, Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production.

I have read few books as thought provoking as this.

It is only possible to go through a small subset of Smil's writings and still have a life, but to the extent I have over the years, and whenever I have, I've been impressed with his vast knowledge of industrial processes, their interface with energy, and his associated stark realism, and if nothing else, they are stark.

Recently while reflecting on Richard Feynman's 1959 lecture, "There's Room at the Bottom" which predicted the information age and the nanotechnology age which has come to pass, I was inspired to refer to the book where I first encountered it - it's in the appendix - the Second Edition of Bradley Fahlman's wonderful text Materials Chemistry - and I found myself wandering to Chapter 3 in the book which is entitled "Metals."

Reading through sections of it I was reminded of one of Smil's writings that has really troubled me for years and challenged my technological thinking - and by the way I don't always agree with Smil but one has to think very deeply if one wants to seriously disagree with many of his profound insights - specifically, this one from 2009: The Iron Age & Coal-based Coke: A Neglected Case of Fossil-fuel Dependence.

(It comes from a "Free Market" blog, and I assure you that I am in no way a "free marketeer," since I am more inclined to think about sustainability, the very long term, as opposed to the psychology of our short term amoral generation of fools and "economic realities" that some people put forth, usually as I encounter them with the fraudulent statements that "solar energy is cheaper than grid energy," or "renewables are the fastest growing source of energy capacity." )

However much Smil and I may disagree on political economics however, I am certainly not in the mainstream of my political party, the Democratic Party - inasmuch as I think that the magical thinking that betting the future of the planetary atmosphere on wind and solar energy is at best wasteful and at worst tragic - I certainly agree with the introduction of his writing on the iron age:

As an old-fashioned scientist, I prefer hard engineering realities to all those interminably vacuous and poorly informed policy “debates” that feature energy self-sufficiency (even Saudis import!), sustainability (at what spatial and temporal scales?), stakeholders (are not we all, in a global economy?) and green economy (but are not we still burning some 9 billion tonnes of carbon annually?).

High regard for facts and low regard for wishful thinking has forced me to deal repeatedly with many energy illusions–if not outright delusions–and to point out many complications and difficulties to be encountered during an inevitably lengthy transition from an overwhelmingly fossil-fueled world to economies drawing a substantial share of their primary energies from renewable sources.


I personally believe that the only sustainable form of energy is the cleanest and safest form of energy, nuclear energy. This is not, by the way, a statement that nuclear energy is without risk or that it is or has proved to be always harmless - clearly it hasn't - but my words contain the relational suffix "-est," cleanest, safest. It is merely a statement that nuclear energy is superior to all other options in energy.

Smil's point in the referenced article is that we must have coal because we must have steel.

I, by contrast, have convinced myself that nuclear energy should do everything. Am I engaged in the wishful thinking about which Smil is ever ready to challenge.

Steel...steel...steel...

If you want to get a feel for what's involved in steel, you should head out to Bethlehem, Pennsylvania and tour the steel stacks from the abandoned post industrial facility that used to be the chief plant for the defunct company Bethlehem Steel. The city of Bethlehem was left with this rotting hulk, and with wonderful creativity managed to turn it into a sort of industrial museum that also functions as an arts and music center. One can walk along a catwalk along side the towering retorts with nice little posters on industrial history, including comments on the immigrants who came to work there, and see where the steel for the Empire State Building, the Golden Gate Bridge, and the overwhelming majority of the "liberty ships" that won World War II was made.

It's a worthy afternoon, and if you go in summer, you can catch a nice evening concert on the surrounding grounds.

From Fahlman's book, on the subject of steel processing:

It is estimated that iron constitutes 90% of all applications that involve metals. Hence, it is not surprising that the purification and post-processing for iron is the most widely practiced. The most primitive method that was used in the nineteenth century to purify iron from its ore is called bloomery. This method used pure carbon in the form of charcoal to reduce the metal (Eq. 2). In this process, the temperature is not sufficient to completely melt the iron, so a spongy mass consisting of iron and silicates are formed. Through heat/hammering treatments, the silicates mix into the iron lattice, creating wrought iron. This form of iron was used exclusively by early blacksmiths, since the heating of wrought iron yields a malleable, bendable, and extremely easy compound to work with. Most modern applications for metallic iron are steel related, exploiting its high hardness, ductility and tensile strength. Figure 3.3 shows a flowchart for the various procedures that are used for modern steelmaking. The first step uses a blast furnace [3] that is comprised of a massive, refractory-lined steel column wherein pelletized iron ore, charcoal, and calcium sources (from limestone and dolomite) are poured into the top, and a large jet of pre-heated (ca. 1,050_C) air is blown in from the bottom. As mixing of the components occurs at various temperature regimes, the various oxides present in the ore are reduced to metallic iron. From the coolest – hottest portions of the blast oven, corresponding to the highest – lowest regions, respectively, the following oxides are reduced (Figure 3.4):

1. 500–600C: 1.Hematite (Fe2O3)
2. 600–900C: Magnetite (Fe3O4)
3. 900–1,100_C: Wustite (FeO)
4. >1,100_C : FeO0.5

Since iron ore is largely comprised of aluminosilicate minerals, a byproduct is also formed within the blast furnace, known as slag (ca. 30–40 wt.% SiO2, 5–10 wt.% Al2O3, 35–45 wt.% CaO, 5–15 wt.% MgO, and 5–10 wt.% CaS).
It should be noted that it takes 6–8 h for the native iron ore to descend toward the bottom of the blast furnace, but only ca. 8 s for the pre-heated air to reach the top of the furnace. Oftentimes, a fused solid known as sinter is also added to the blast furnace, which is comprised of fine particulates of iron ore, coke, limestone and other steel plant waste materials that contain iron. The reducing agent within the blast furnace (coke) is comprised of 90–93% carbon, and is formed by heating coal to remove the volatile components such as oil and tar. The coke is ignited at the bottom of the blast furnace immediately upon contact with the air blast; since there is excess carbon in the furnace, the active reducing species is CO rather than CO2.


You get the idea...

Further text refers to the removal of sulfur from the pig iron, using calcium oxide, "burnt lime," itself requiring a huge investment in heat for manufacture at 1400C and then transferring the molten metal using a ladle to the "BOF," the basic oxygen furnace, where the metal is treated with a supersonic jet of pure oxygen with the temperature rising to 1700C to remove phosphorous, carbon, manganese and silicon.

Later there's reference to the use of pure argon gas for alloying purposes. The purification of argon, which represents about 1% of the atmosphere is also an extremely energy intensive process.

There's quite a bit in this text, including some wonderful pictures of a steel plant in Dearborn, Michigan, Sevarstar Steel, then the American subsidiary of a Russian company that as of today has been sold to an American company AK Steel. The chapter also contains wonderful pictures of other industrial facilities to process other metals. If you can find access to this book, and you're at all interested on a profound level on the subject of sustainability, it's almost an essential read, along with reading Smil.

Smil's argument is that there is simply not enough carbon available in biomass to replace coal.

I would counter that there is certainly enough carbon in the atmosphere to replace coal however, if one can reduce it.

In the future in this space, I hope to write a commentary on a paper in the current issue of Chemical Reviews which is dedicated to "Sustainable Chemistry" to discuss carbon dioxide/water splitting thermochemical cycles.

Is it conceivable that we can replace carbon from coal for processing iron with nuclear energy? I believe it is. Is it easy to do so? Probably not. My impression is, however, that irrespective of overcoming the unsustainable temporal psychology of "free markets" we have a moral obligation to all future generations to explore this.

My insomnia, under which I write this piece is finally being overcome, and I'm going for a nap. If interested, stay tuned. I'll leave you with a link to what Vaclav Smil sees when he sees a wind turbine, with a cool graphic dripping with oil:

What I See When I See a Wind Turbine

I see something different, something worse than Smil sees - the future unless we change our minds - but neither of us are fond of wind energy, which is not clean, not "green" and not sustainable.

Have a pleasant weekend.

Porous Rhodium Copper Nanospheres.

In my electronic files, I have a copy of the Second Edition of Bradley Fahlman's wonderful text Materials Chemistry - a Third Edition either has, or is about to be released - which in its Appendix B reproduces a December 1959 lecture by Richard Feynman entitled "There's Room at the Bottom," in which he discusses a putative world in which it is possible to print the Encyclopedia Britannica on the head of a pin.

His speech began like this:

I would like to describe a field, in which little has been done, but in which an enormous amount can be done in principle. This field is not quite the same as the others in that it will not tell us much of fundamental physics (in the sense of, ‘What are the strange particles?’) but it is more like solid-state physics in the sense that it might tell us much of great interest about the strange phenomena that occur in complex situations. Furthermore, a point that is most important is that it would have an enormous number of technical applications. What I want to talk about is the problem of manipulating and controlling things on a small scale.

As soon as I mention this, people tell me about miniaturization, and how far it has progressed today. They tell me about electricmotors that are the size of the nail on your small finger. And there is a device on the market, they tell me, by which you can write the Lord’s Prayer on the head of a pin. But that’s nothing; that’s the most primitive, halting step in the direction I intend to discuss. It is a staggeringly small world that is below. In the year 2000, when they look back at this age, they will wonder why it was not until the year 1960 that anybody began seriously to move in this direction. Why cannot we write the entire 24 volumes of the Encyclopedia Brittanica on the head of a pin?

Let’s see what would be involved...


Later he continues in what seemed to him to be a perfectly reasonable possibility, although I'm not sure that everyone in his audience found it believable:

What would happen if I print all this down at the scale we have been discussing?

How much space would it take? It would take, of course, the area of about a million pinheads because, instead of there being just the 24 volumes of the Encyclopaedia, there are 24 million volumes. The million pinheads can be put in a square of a thousand pins on a side, or an area of about 3 square yards. That is to say, the silica replica with the paper-thin backing of plastic, with which we have made the copies, with all this information, is on an area of approximately the size of 35 pages of the Encyclopaedia. That is about half as many pages as there are in this magazine. All of the information which all of mankind has every recorded in books can be carried around in a pamphlet in your hand – and not written in code, but a simple reproduction of the original pictures, engravings, and everything else on a small scale without loss of resolution.

What would our librarian at Caltech say, as she runs all over from one building to another, if I tell her that, 10 years from now, all of the information that she is struggling to keep track of – 120,000 volumes, stacked from the floor to the ceiling, drawers full of cards, storage rooms full of the older books – can be kept on just one library card! When the University of Brazil, for example, finds that their library is burned, we can send them a copy of every book in our library by striking off a copy from the master plate in a few hours and mailing it in an envelope no bigger or heavier than any other ordinary air mail letter.

Now, the name of this talk is ‘There is Plenty of Room at the Bottom’ – not just ‘There is Room at the Bottom.’ What I have demonstrated is that there is room – that you can decrease the size of things in a practical way. I now want to show that there is plenty of room. I will not now discuss how we are going to do it, but only what is possible in principle – in other words, what is possible according to the laws of physics. I am not inventing anti-gravity, which is possible someday only if the laws are not what we think. I am telling you what could be done if the laws are what we think; we are not doing it simply because we haven’t yet gotten around to it.


1959...Remarkable...completely and totally remarkable.

As we all know the world that Feynman predicted in 1959 has come to pass. I can easily carry Fahlman's book, and a thousand books like it, plus thousands of copies of papers, photographs in my pocket on a thumb drive, which is something I do frequently.

What is more remarkable is that it is how possible to actually see things at an atomic scale. I had a nice tour with my son of the materials science department that he ultimately went to school, and the nice graduate student who conducted the tour took us to see a whole bunch of different microscopes, including an tunneling electron microscope where he displayed a photography of, um, atoms.

Whatever.

This is a brief note about a nanotechnical approach to utilizing vanishing resources more carefully.


I'm sure I've posted this periodic table in this space before, which shows the "critical elements" that are expected to run out, at least in traditionally processed ores accessible at low prices and utilized using current technology:



One may quibble a bit on the data this table represents - I have argued that because of its high energy density supplies of uranium are inexhaustible, for example - but I'm quite sure, the regrettable circumstance of "peak oil" not having come to pass - that in most cases the table explicates a serious threat to future generations; that many elements will become inaccessible.

One of the elements in red, element 45, rhodium is the one I'd like to discuss by pointing to a paper I came across today (and put on my thumb drive), this one: Mesoporous Bimetallic RhCu Alloy Nanospheres Using a Sophisticated Soft-Templating Strategy (Yamauchi et al, Chem. Mater., 2018, 30 (2), pp 428–435)

Rhodium is an important catalyst; it also serves as a minor constituent of alloys of profound technological importance.

According to another paper from a few years back (Electrochemical behavior of rhodium(III) in 1-butyl-3-methylimidazolium chloride ionic liquid, Srinivasan et al, Electrochimica Acta Volume 53, Issue 6, 15 February 2008, Pages 2794-2801) supplies of this element from terrestrial ores will actually be lower than the quantities available for isolation from used nuclear fuel.

The Yamuchi paper has a nice description of some of the important uses of rhodium catalysts:

Rh is an important precious metal because it can catalyze a diverse range of chemical reactions, including the selective hydrogenation of fine chemicals, energy generation via fuel cells, and remediation of toxic gases.1−3 Increasing the surface area of Rh-based heterogeneous catalysts has a dual advantage of increasing material utilization efficiency and presenting additional catalytically active sites at the atomic steps, corners, and defects of the crystal.4−6 For example, Huang et al. provided a platform to carry out the structure-dependent catalytic investigation toward electrocatalytic application via systematically demonstrating three types of Rh nanocrystals (tetrahedron, concave tetrahedron, and nanosheet).7 Our group recently developed a method to manipulate the interior space of nanocrystals by synthesizing mesoporous Rh nanospheres which serve as high performance catalysts for methanol oxidation and nitric oxide (NO) remediation.8 Additionally, ultrathin Rh nanosheets with abundant exposed Rh atoms showed excellent performance for hydrogenation and hydroformylation reactions.9 Yet, despite the progress on developing nanostructured Rh catalysts, the costliness and lack of earth abundance of Rh metal is an unavoidable drawback that limits large-scale applications.


The authors explore then, the Feynman solution, which is to make nanoparticles consisting of a copper rhodium allow in porous perforated spheres:

The high surface area and connectivity of mesoporous/ nanoporous architectures enable several improvements over conventional catalysts.17−19 Making bimetallic interconnected nanostructured networks is the next logical step to realize more efficient utilization of precious metals in high surface area; and reagent permeable catalysts.20−22 Hard-templating, soft-templating, and dealloying are just some of the many ways to generate mesoporous/nanoporous metals.23 In most cases, however, the recent success in synthesizing bimetallic metals has been limited to Pt- and Pd-based catalysts.24−28 Rh-based alloys are particularly challenging in the context of nanoporous Rh-based alloys because the surface energy of Rh is much higher than those of similar noble metals (e.g., Pt, Au, and Pd). Therefore, a more refined approach is required to generate Rhbased alloys with nanoporous structures. Here, we describe a simple method to synthesize mesoporous bimetallic RhCu nanospheres via a soft-templating method using polymeric micelles made of diblock copolymer, poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b- PMMA), as illustrated in Scheme 1.


Scheme 1 as a graphic:




The caption:

Ascorbic acid serves as the reducing agent, while DMF and H2O are the cosolvents. The synthetic process can be divided into five main steps: (1) Addition of water causes the PEO-b-PMMA copolymers to self-assemble into spherical micelles with a PMMA core and a PEO shell. (2) Na3RhCl6, CuCl2, and ascorbic acid are dissolved into the reaction solution. The metal ions form aqua-complexes with the PEO moieties via hydrogen bonding. (3) The Rh and Cu species are coreduced to begin to nucleate. (4) The particles grow and eventually envelope the micelle templates. (5) The templates are finally removed by solvent extraction.


A scanning electron microscope picture of the resulting balls:



The caption:

Figure 1. SEM images of (a) mesoporous Rh100, (b) mesoporous Rh82Cu18, (c) mesoporous Rh69Cu31, (d) mesoporous Rh55Cu45, (e) mesoporous Rh43Cu57, and (f) mesoporous Rh24Cu76 samples.



A tunneling electron microscope picture of them, touching on the atomic scale:



The caption:

Figure 3. (a) TEM image, (b) HAADF-STEM, (c−e) elemental mapping images, and (f) line-scanning compositional profile of mesoporous Rh82Cu18 nanospheres.


Rhodium is a high melting metal; its alloy with copper melts lower. The authors suggest that this morphology actually overcomes the tendency for other copper rhodium systems to agglomerate, thus reducing the catalytic efficiency and lifetime.

Cool I think. This sort of thing should extend rhodium resources, at least until the human race comes to its senses and begins to utilize the valuable materials in used nuclear fuel.

Have a pleasant "hump day" tomorrow.
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