Daegu Gyeongbuk Institute of Science and Technology researchers led by Professor Su-Il In from Department of Energy Science and Engineering have developed high-efficiency photocatalysts that convert carbon dioxide into methane or ethane with graphene-covered reduced titanium dioxide. The finding is expected to be utilized in the carbon dioxide reduction and recycling industries.

(a) Sample pictures obtained at different stages of synthesis Image Credit: Daegu Gyeongbuk Institute of Science and Technology. Click image for the largest view.

Thanks to the global warming craze and the desire to shift to reusable fuel for existing resources due to reserve depletion, research on photocatalysts, which are essential in converting carbon dioxide and water into hydrocarbon fuels, is gaining attention.

The team’s research paper has been published in the journal Energy & Environmental Science.

Although many semiconductor materials with large band gaps are often used in photocatalyst studies, they are limited in absorbing solar energy in various areas. Thus, photocatalyst studies focusing on improving the photocatalyst structure and surface to increase solar energy absorption areas or utilizing two-dimensional materials with excellent electron transmission are under way.

Professor In’s research team developed a high-efficiency photocatalyst that can convert carbon dioxide into methane (CH4) or ethane (C2H6) by placing graphene on reduced titanium dioxide in a stable and efficient way.

The photocatalyst developed by the research team can selectively convert carbon dioxide from a gas to methane or ethane. The results showed that its generation volume is 259umol/g and 77umol/g of methane and ethane respectively and its conversion rate is 5.2% and 2.7% higher than conventional reduced titanium dioxide photocatalysts. In terms of ethane generation volume, this result shows the world’s highest efficiency under similar experimental conditions.

In addition, the research team proved for the first time that the pore moves toward graphene due to band bending phenomena visible from titanium dioxide and graphene interfaces through the international joint research conducted with the research team led by James R. Durrant at the Department of Chemistry of Imperial College London (ICL), UK using photoelectron spectroscopy.

The movement of the pore towards graphene activates reactions by causing electrons to gather on the surface of the reduced titanium dioxide and forms a large amount of radical methane (CH3) as polyelectrons engage in the reactions. The research team identified a mechanism for producing methane if this formed radical methane reacts with hydrogen ions and for producing ethane if the radical methane reacts with each other.

The catalyst material developed by the research team is expected to be applied to a variety of areas such as high-value-added material production in the future and be used to solve global warming problems and energy resource depletion issues by selectively producing higher levels of hydrocarbon materials using sunlight.

Professor In said, “The reduced titanium dioxide photocatalyst with graphene that has been developed this time has the advantage of being able to selectively produce CO2 as a usable chemical element such as methane or ethane. By conducting follow-up research that increases the conversation rate so that it can be commercialized, we will contribute to the development of technology for reducing carbon dioxide and turning it into a resource.”

Some time will be needed to tell if the team’s work can scale up economically. Then there are the questions. Foremost is what is the hydrogen source? There are many more that the press release isn’t addressing.

We’ll presume these matters are worked out over time and as scaling up is attempted the economics will become clear. One more press release please?

University of Wisconsin-Madison researchers have identified two changes to a single gene that can make the yeast tolerate the pretreatment chemicals. Some chemicals used in pretreatment to speed up the breakdown of plants for production of biofuels like ethanol are poisonous to the yeasts that turn the plant sugars into fuel.

Researchers from the University of Wisconsin-Madison and several Department of Energy laboratories have identified two changes to a single gene that can make the yeast tolerate the pretreatment chemicals.

They published their findings recently in the journal Genetics.

Great Lakes Bioenergy Research Center scientist Trey Sato examines a yeast strain in the Experimental Fermentation Lab at UW–Madison. Image Credit: James Runde, UW-M. Click image for the largest view.

Even in a cutting-edge factory, turning plant material like grasses or leftover cornstalks into biofuels often mimics the way nature returns plant nutrients to the soil, air and water. One way or another, the plant cells are broken down physically, chemically and with microbes, almost like it would decompose naturally.

Trey Sato, a senior scientist at the UW-Madison-based Great Lakes Bioenergy Research Center and a lead researcher on the yeast study explained, “But the process of decomposing plant material is really slow. It takes years for a fallen tree to completely decompose. That length of time isn’t compatible with industrial situations, where the goal is to make as much product as fast as possible in order to get it to market for sale.”

So biofuels manufacturers speed up the process in part by pretreating the raw plant biomass. Pretreatment may include applying ammonia gas, acids, heat and pressure, salts called ionic liquids, or some combination of those and other schemes.

After pretreatment, the cellulose that makes up the plant cell walls and fibers is broken down with enzymes to release sugar. The sugar is fermented into fuel by microbes – often carefully bred and engineered versions of the yeast Saccharomyces cerevisiae, also used to ferment wine and beer and leaven bread.

“Those ionic liquids are useful for pretreating and getting the process started,” Sato said. “The problem is that even after you go to the trouble to remove and recover as much of the ionic liquids as you can from your biomass before you do the fermenting, the amount you can’t get out is enough to be toxic to a lot of microbes.”

This toxicity is enough to make the yeast as much as 70 percent less efficient at turning sugar into biofuel, a crippling loss for an industrial process.

Sato and collaborators at UW-Madison, the Joint BioEnergy Institute and Lawrence Livermore, Lawrence Berkeley and Sandia national laboratories went looking for a way to overcome this barrier.

“Nature is probably the best engineer there is. It’s had millions of years of evolution to develop and optimize biological systems,” Sato said. “So one solution might be to go out and find a replacement for yeast, a different microbe that might be able to ferment cellulosic sugars and also stomach the ionic liquids.”

But many biofuels companies and engineers have invested a great deal of time and resources in tweaking their own yeast and building biofuel reactors around their preferred strains. A different fermenting organism might put them back at square one.

So, the researchers looked to a variety of S. cerevisiae strains that were isolated from different ecological niches. Of the 136 yeast isolates they surveyed, they found one strain with outstanding tolerance to ionic liquids. They screened DNA sequences from this strain and identified a pair of genes key to surviving the otherwise toxic pretreatment chemicals. One of the genes, called SGE1, makes a protein that settles in the yeast cell membrane and works as a pump to remove toxins.

“If you have more of these pumps at the cell surface, you can get more of the ionic liquid molecules out of your cell,” Sato said.

A change of just two individual nucleotides among more than 12 million that make up the yeast genome are enough to increase the production of those cellular pumps and protect yeast from ionic liquids. The researchers used the gene-editing tool CRISPR to alter a strain of an ionic liquid-susceptible yeast, introducing the two single-nucleotide changes and successfully producing a yeast that can survive – and ferment – alongside amounts of ionic liquid that are normally toxic.

“Now anyone using this yeast can look at a specific gene in their own strain and tell whether it’s compatible and useful with an ionic liquid process or not,” said Sato. “It’s a simple engineering procedure, which doesn’t take long and isn’t expensive. And it can be fixed with CRISPR in a matter of a week or two.”

Sato said the next step is to try out the modified yeast outside the lab, incorporating the real-world plant material used as biofuel feedstock.

Collaborators on the study included Michael Thelen of the Joint BioEnergy Institute and UW-Madison genetics professors Audrey Gasch and Chris Hittinger and biochemistry and bacteriology professor Robert Landick.

This looks like a success on going to more ethanol from cellulosic feedstocks. But for now, sugar cane and corn sourced ethanol are the low cost leaders. Both are economically under priced and the oil refining business is worrying away at ethanol fuel gaining of market share to the energy resources of the world. It looks like decades of more fighting to come.

Binghamton University researchers have created a biodegradable, paper-based battery that is more efficient than previously possible. It may be that batteries of the future may be made out of paper.

Researchers at Binghamton University, State University at New York have created a biodegradable, paper-based battery that is more efficient than previously possible.  Image Credit: Seokheun ‘Sean’ Choi, Binghamton University. Click image for the largest view.

The idea is a stretch, but for years there has been excitement in the scientific community about the possibility of paper-based batteries as an eco-friendly alternative. However, the proposed designs were never quite powerful enough, they were difficult to produce and it was questionable whether they were really biodegradable.

The Binghamton researchers think their new design solves all of those problems.

Associate Professor Seokheun “Sean” Choi from the Electrical and Computer Engineering Department and Professor Omowunmi Sadik from the Chemistry Department worked on the project together. Choi engineered the design of the paper-based battery, while Sadik was able to make the battery a self-sustaining “biobattery”.

“There’s been a dramatic increase in electronic waste and this may be an excellent way to start reducing that,” said Choi. “Our hybrid paper battery exhibited a much higher power-to-cost ratio than all previously reported paper-based microbial batteries.”

The biobattery uses a hybrid of paper and engineered polymers. The polymers – poly (amic) acid and poly (pyromellitic dianhydride-p-phenylenediamine) – were the key to giving the batteries biodegrading properties. The team tested the degradation of the battery in water and it clearly biodegraded without the requirements of special facilities, conditions or introduction of other microorganisms.

The polymer-paper structures are lightweight, low-cost and flexible. Choi said that flexibility also provides another benefit.

“Power enhancement can be potentially achieved by simply folding or stacking the hybrid, flexible paper-polymer devices,” said Choi.

The team said that producing the biobatteries is a fairly straightforward process and that the material allows for modifications depending on what configuration is needed.

The team’s research paper, titled “Green Biobatteries: Hybrid Paper-Polymer Microbial Fuel Cells,” has been published in Advanced Sustainable Systems.

The work was supported by a grant from the National Science Foundation and done through the Center for Research in Advanced Sensing Technologies and Environmental Sustainability.

Admittedly the first impression might be why bother, but in truth, except for the large lead acid car starting and deep discharge batteries, recycling is vastly disappointing. Throw away alkaline batteries are plenty noxious, some of the rechargeables are toxic. So there is a highly desirable point in safer, after use, battery technology.

The study paper is behind a paywall, so there isn’t the customary news on just how much energy by weight and volume has been accomplished. But there will be many steps to get to market. This is one more worthy one.

Tokyo Institute of Technology scientists have addressed one of the major disadvantages of all-solid-state batteries by developing batteries with a low resistance at their electrode/solid electrolyte interface.

The fabricated batteries showed excellent electrochemical properties that greatly surpass those of traditional and ubiquitous Li-ion batteries; thereby, demonstrating the promise of all-solid-state battery technology and its potential to revolutionize portable electronics.

Structure of the thin-film all-solid-state batteries. The batteries were made by stacking various layers via thin-film deposition methods. The LNMO/Li3PO4 interface showed spontaneous migration of Li ions and had an unprecedentedly low resistance. Image Credit: Tokyo Institute of Technology. Click image for the largest view.

Most consumers are familiar with rechargeable lithium ion batteries, which have been developing over the last few decades, and are now common in all sorts of electronic devices. Despite their broad use, scientists and engineers believe that traditional Li-ion battery technology is already nearing its full potential and new types of batteries are needed.

The team described their work in a paper published in ACS Applied Materials & Interfaces.

All-solid-state batteries are a new type of Li-ion battery, and have been shown to be potentially safer and more stable energy-storing devices with higher energy densities. However, the use of such batteries is limited due to a major disadvantage: their resistance at the electrode/solid electrolyte interface is too high, hindering fast charging and discharging.

Scientists from Tokyo Institute of Technology and Tohoku University, led by Professor Taro Hitosugi, fabricated all-solid-state batteries with extremely low interface resistance using Li(Ni0.5Mn1.5)O4 (LNMO), by fabricating and measuring their batteries under ultrahigh vacuum conditions, ensuring that the electrolyte/electrode interfaces were free of impurities.

After fabrication, the electrochemical properties of these batteries were characterized to shed light on Li-ion distribution around the interface. X-ray diffraction and Raman spectroscopy were used for analyzing the crystal structure of the thin films comprising the batteries.

Spontaneous migration of Li ions was found to occur from the Li3PO4 layer to the LNMO layer, converting half the LNMO to L2NMO at the Li3PO4/LNMO interface. The reverse migration occurs during the initial charging process to regenerate LNMO.

The resistance of this interface, verified using electrochemical impedance spectroscopy, was 7.6 Ω cm2, two orders of magnitude smaller than that of previous LMNO-based all-solid-state batteries and even smaller than that of liquid-electrolyte-based Li-ion batteries using LNMO. These batteries also displayed fast charging and discharging, managing to charge/discharge half the battery within just one second.

Moreover, the cyclability of the battery was also excellent, showing no degradation in performance even after 100 charge/discharge cycles.

Li(Ni0.5Mn1.5)O4 is a promising material to increase the energy density of a battery, because the material provides a higher voltage. The research team hopes that these results will facilitate the development of high-performance all-solid-state batteries, which could revolutionize modern portable electronic devices and electric cars.

Batteries seem to generate the most news and press releases and for many the progress seems slow. But the little incremental improvements are seldom if ever announced in product releases to consumes.

But when solid state lithium ion comes to market you’re sure to see a blurb on the packaging. And it will be a much higher capacity longer lasting battery.

The American Chemical Society is reporting, with open access, in ACS Central Science a new catalyst that is really the best of both worlds. Taking water and ripping it apart into hydrogen and oxygen could form the basis of artificial photosynthetic devices that could ultimately power homes and businesses.

However, catalysts, including those used to ‘split’ water, have either worked well but are expensive and unstable, or are affordable and stable, but don’t work as well.

Identifying ideal materials that can split water is a long-standing problem in renewable energy storage. Catalysts, which help reactions occur, are often used in this process.

The synthesis strategy for side-on and end-on bound DHCs. The binding mode is defined by the structure of the substrate. When dual binding sites with the suitable density and distance are available (such as on Fe2O3, panel A), a side-on mode is preferred. Otherwise, the end-on mode is preferred (such as on WO3, panel B). Image Credit: ACS Central Science. Click image for the largest view. Use the study paper link above for complete details.

“Homogeneous” ones dissolve into the reaction solution and are usually active and selective. However, they don’t work well in some applications because they are unstable and expensive. In contrast, “heterogeneous” catalysts are solids that are stable, recyclable and convenient to work with, but they are usually not very active or selective.

Dunwei Wang and the colleague team proposed they could get closer to the ideal catalyst by producing a hybrid material.

The researchers developed a new hybrid catalyst made of iridium dinuclear heterogeneous catalysts (DHCs) attached to a tungsten oxide substrate. They found that attaching the ends of the DHC molecules – instead of the sides – allowed the catalyst to perform optimally. The researchers suggest that this first-of-its-kind material could be an important step toward alternative solar energy storage or artificial photosynthesis.

The journal paper is open access and while technical is good at explaining what goes on. This development is quite an improvement in a field fraught with ideas that just don’t work out. This work is a strong step into how a forever fueled world might work.

Its interesting no claim of total success is made, rather the insights gained are in full view. This is an honorable team worthy of respect and some admiration. They may be further along than they allow, replication will surely take this further. This is science at its best.


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