University of Cambridge researchers have developed a standalone device that converts sunlight, carbon dioxide and water into a carbon-neutral fuel, without requiring any additional components or electricity.

The device, developed by a team from the University of Cambridge, in collaboration with the team of Professor Kazunari Domen from the University of Tokyo, a co-author of the study, is a significant step toward achieving artificial photosynthesis – a process mimicking the ability of plants to convert sunlight into energy. It is based on an advanced ‘photosheet’ technology and converts sunlight, carbon dioxide and water into oxygen and formic acid – a storable fuel that can be either be used directly or be converted into hydrogen.

Image Credit: University of Cambridge. Click image for the largest view.

The results, reported with a paper published in the journal Nature Energy, represent a new method for the conversion of carbon dioxide into clean fuels. The wireless device could be scaled up and used on energy ‘farms’ similar to solar farms, producing clean fuel using sunlight and water.

Harvesting solar energy to convert carbon dioxide into fuel is a promising way to reduce carbon emissions and transition away from fossil fuels. However, it is challenging to produce these clean fuels without unwanted by-products.

First author Dr Qian Wang from Cambridge’s Department of Chemistry said, “It’s been difficult to achieve artificial photosynthesis with a high degree of selectivity, so that you’re converting as much of the sunlight as possible into the fuel you want, rather than be left with a lot of waste.”

Professor Erwin Reisner, the paper’s senior author said, “In addition, storage of gaseous fuels and separation of by-products can be complicated. We want to get to the point where we can cleanly produce a liquid fuel that can also be easily stored and transported.”

In 2019, researchers from Reisner’s group developed a solar reactor based on an ‘artificial leaf’ design, which also uses sunlight, carbon dioxide and water to produce a fuel, known as syngas. The new technology looks and behaves quite similarly to the artificial leaf but works in a different way and produces formic acid.

While the artificial leaf used components from solar cells, the new device doesn’t require these components and relies solely on photocatalysts embedded on a sheet to produce a so-called photocatalyst sheet. The sheets are made up of semiconductor powders, which can be prepared in large quantities easily and cost-effectively.

In addition, this new technology is more robust and produces clean fuel that is easier to store and shows potential for producing fuel products at scale. The test unit is 20 square centimeters in size, but the researchers say that it should be relatively straightforward to scale it up to several square meters. In addition, the formic acid can be accumulated in solution, and be chemically converted into different types of fuel.

“We were surprised how well it worked in terms of its selectivity – it produced almost no by-products,” said Wang. “Sometimes things don’t work as well as you expected, but this was a rare case where it actually worked better.”

The carbon-dioxide converting cobalt-based catalyst is easy to make and relatively stable. While this technology will be easier to scale up than the artificial leaf, the efficiencies still need to be improved before any commercial deployment can be considered. The researchers are experimenting with a range of different catalysts to improve both stability and efficiency.

The researchers are now working to further optimize the system and improve efficiency. Additionally, they are exploring other catalysts for using on the device to get different solar fuels.

Reisner noted, “We hope this technology will pave the way toward sustainable and practical solar fuel production.”

There have been quite a few of these solar driven recycling CO2 back to fuel ideas make progress. This one looks especially promising. Its worth noting that we still are not seeing costs of them or the area needed for solar irradiation to get to economic scale.

Perhaps we’re getting closer to that kind of information. With that data included we might get from very interesting to hopeful.

University of Bern has led an international research team that has succeeded in developing an electrocatalyst for hydrogen fuel cells which, in contrast to the catalysts commonly used today, does not require a carbon carrier and is therefore much more stable. The new process is industrially applicable and can be used to further optimize fuel cell powered vehicles without CO2 emissions.

The new electrocatalyst for hydrogen fuel cells consists of a thin platinum-cobalt alloy network and, unlike the catalysts commonly used today, does not require a carbon carrier. © Gustav Sievers. Image Credit: University of Bern. Click image for the largest view.

Fuel cells are gaining in importance as an alternative to battery-operated electromobility in heavy traffic, especially since hydrogen is a CO2-neutral energy carrier if it is obtained from renewable sources.

For efficient operation, fuel cells need an electrocatalyst that improves the electrochemical reaction in which electricity is generated. The platinum-cobalt nanoparticle catalysts used as standard today have good catalytic properties and require only as little as necessary rare and expensive platinum.

In order for the catalyst to be used in the fuel cell, it must have a surface with very small platinum-cobalt particles in the nanometer range, which is applied to a conductive carbon carrier material. Since the small particles and also the carbon in the fuel cell are exposed to corrosion, the cell loses efficiency and stability over time.

The international team, led by Professor Matthias Arenz from the Department of Chemistry and Biochemistry (DCB) at the University of Bern, has now succeeded in using a special process to produce an electrocatalyst without a carbon carrier, which, unlike existing catalysts, consists of a thin metal network and is therefore more durable.

Professor Arenz said, “The catalyst we have developed achieves high performance and promises stable fuel cell operation even at higher temperatures and high current density.”

The results have been published in Nature Materials. The study is an international collaboration between the DCB and, among others, the University of Copenhagen and the Leibniz Institute for Plasma Science and Technology, which also used the Swiss Light Source (SLS) infrastructure at the Paul Scherrer Institute.

In a hydrogen fuel cell, hydrogen atoms are split to generate electrical power directly from them. For this purpose, hydrogen is fed to an electrode, where it is split into positively charged protons and negatively charged electrons. The electrons flow off via the electrode and generate electric current outside the cell, which drives a vehicle motor, for example. The protons pass through a membrane that is only permeable to protons and react on the other side on a second electrode coated with a catalyst (here from a platinum-cobalt alloy network) with oxygen from the air, thus producing water vapor. This is discharged via the “exhaust.”

For the fuel cell to produce electricity, both electrodes must be coated with a catalyst. Without a catalyst, the chemical reactions would proceed very slowly. This applies in particular to the second electrode, the oxygen electrode. However, the platinum-cobalt nanoparticles of the catalyst can “melt together” during operation in a vehicle. This reduces the surface of the catalyst and therefore the efficiency of the cell. In addition, the carbon normally used to fix the catalyst can corrode when used in road traffic. This affects the service life of the fuel cell and consequently the vehicle.

Professor Arenz explained, “Our motivation was therefore to produce an electrocatalyst without a carbon carrier that is nevertheless powerful.” Previous, similar catalysts without a carrier material always only had a reduced surface area. Since the size of the surface area is crucial for the catalyst’s activity and hence its performance, these were less suitable for industrial use.

The researchers were able to turn the idea into reality thanks to a special process called cathode sputtering. With this method, a material’s individual (here platinum or cobalt) are dissolved (atomized) by bombardment with ions. The released gaseous atoms then condense as an adhesive layer. “With the special sputtering process and subsequent treatment, a very porous structure can be achieved, which gives the catalyst a high surface area and is self-supporting at the same time. A carbon carrier is therefore superfluous,” says Dr. Gustav Sievers, lead author of the study from the Leibniz Institute for Plasma Science and Technology.

Professor Arenz summing up said, “This technology is industrially scalable and can therefore also be used for larger production volumes, for example in the automotive industry.” This process allows the hydrogen fuel cell to be further optimized for use in road traffic. “Our findings are consequently of importance for the further development of sustainable energy use, especially in view of the current developments in the mobility sector for heavy goods vehicles.”

This is very good news for the hydrogen fueled motors folks. Fuel cells would need a very expensive supply of platinum, which now it seems, could last much longer. How much longer is still an unknown, and the price of platinum if a market came to be, are two very important questions. And that hydrogen storage problem is still out there.

Washington State University researchers have made a key first step in economically converting plant materials to fuels: keeping iron from rusting.

The researchers have determined how to keep iron from rusting in important chemical reactions that are needed to convert plant materials to fuels, meaning that the cheap and readily available element could be used for cost-effective biofuels conversion.

Researchers have been trying to find more efficient ways to create fuels and chemicals from renewable plant-based resources, such as from algae, crop waste, or forest residuals. But, these bio-based fuels tend to be more expensive with less energy density than fossil fuels.

One big hurdle in using plant-based feedstocks for fuel is that oxygen has to be removed from them before they can be used.

WSU researchers have made a key first step in economically converting plant materials to fuels: keeping iron from rusting. They report on their work on the cover of the July issue of ACS Catalysis. Image Credit: Washington State University. Click image for the largest view.

Led by Yong Wang, Voiland Distinguished Professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, and Shuai Wang from the State Key Laboratory for Physical Chemistry of Solid Surfaces at Xiamen University, the researchers report on their work on the cover of the July issue of ACS Catalysis.

Jean-Sabin McEwen, a co-author on the paper and associate professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering said, “You want to use the cheapest catalyst to remove the oxygen. Iron is a good choice because it’s super abundant.”

Iron-based catalysts show great promise for being able to remove oxygen, but because the plant materials also contain oxygen, the iron oxidizes, or rusts, during the reaction, and then the reaction stops working. The trick is to get the iron to remove the oxygen from the plants without taking up so much oxygen that the reaction stops.

In their work, the researchers anchored their iron catalyst with a carbon structure that was modified to incorporate nitrogen. The structure modifies the properties of the iron, so that it interacts less with oxygen while it continues to do the required work of removing oxygen from the plant material. The researchers used the nitrogen as a sort of control dial to tune the iron’s interaction with oxygen.

In another recently published paper in Chemical Science led by Yong Wang and Junming Sun, a research assistant professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, the researchers discovered a durable iron-based catalyst with a thin carbon graphene layer around it. The graphene layer protected the iron while cesium ions allowed the researchers to tailor its electronic properties for the desired reaction.

Sun said, “We dialed down the oxygen reaction. By protecting iron and tuning its properties, these works provide the scientific basis for using earth abundant and cost-effective iron as catalysts for biomass conversion.”

The researchers are now working to better understand the chemistry of the reactions, so they can further increase the reactivity of the iron catalysts. They also will need to try their catalysts with real feedstocks instead of the model compounds used for the study. The feedstocks collected from farm fields will be more complicated in their compositions with a lot of impurities, and the researchers would also have to integrate their catalyst into a series of steps that are used in the conversion process.

“We are trying to make the conversion as economically as possible,” Wang said. “The key is trying to find robust catalysts based on low-cost, earth abundant elements. This is a first step in that direction.”

They have the lab example working and its likely that the commercial development will succeed. On the other hand, stopping iron from rusting is going to be a huge worldwide market that one hopes the team doesn’t overlook.

University of British Columbia researchers can show how a ‘Cold Tube’ can offer relief from the summer heat without relying on air conditioning. A Cold Tube uses half the energy of conventional air conditioners and can be used outdoors or indoors.

Many people beat the summer heat by cranking the air conditioning. However, air conditioners guzzle power and spew out millions of tons of carbon dioxide daily. They’re also not always good for your health – constant exposure to central A/C can increase risks of recirculating germs and causing breathing problems.

A team of researchers from the University of British Columbia, Princeton University, the University of California, Berkeley and the Singapore-ETH Centre say there’s a better alternative. The team’s research paper has been published in the Proceedings of the National Academy of Sciences.

They call it the Cold Tube, and they have shown it works.

Schematic of a Cold Tube radiant cooling panel (Upper) and radiant heat transfer through the IR-transparent membrane (Lower). Image Credit: University of British Columbia. Click image for the largest view. There is a Powerpoint download in the PNAS research article.

Project co-lead Adam Rysanek, assistant professor of environmental systems at UBC’s school of architecture and landscape architecture, whose work focuses on future energy systems and green buildings explained, “Air conditioners work by cooling down and dehumidifying the air around us – an expensive and not particularly environmentally friendly proposition. The Cold Tube works by absorbing the heat directly emitted by radiation from a person without having to cool the air passing over their skin. This achieves a significant amount of energy savings.”

The Cold Tube is a system of rectangular wall or ceiling panels that are kept cold by chilled water circulating within them. Since heat naturally moves by radiation from a hotter surface to a colder surface, when a person stands beside or under the panel, their body heat radiates towards the colder panel. This creates a sensation of cooling like cold air flowing over the body even if the air temperature is quite high.

Although these types of cooling panels have been used in the building industry for several decades, what makes the Cold Tube unique is that it does not need to be combined with a dehumidification system.

Just as a cold glass of lemonade would condense water on a hot summer day, cooling down walls and ceilings in buildings would also condense water without first drying out the air around the panels. The researchers behind the Cold Tube conceived of an airtight, humidity-repelling membrane to encase the chilled panels to prevent condensation from forming while still allowing radiation to travel through.

The team built an outdoor demonstration unit last year in Singapore, inviting 55 members of the public to visit and provide feedback. When the system was running, most participants reported feeling “cool” or “comfortable,” despite an average air temperature of 30° Celsius (86° Fahrenheit). The panels also stayed dry, thanks to the special membrane.

Eric Teitelbaum, a senior engineer at AIL Research who oversaw the demonstration project while working at the Singapore-ETH Centre said, “Because the Cold Tube can make people feel cool without dehumidifying the air around them, we can look towards shaving off up to 50 percent of typical air conditioning energy consumption in applicable spaces.”

“This design is ready. It can obviously be used in many outdoor spaces – think open-air summer fairs, concerts, bus stops and public markets. But the mission is to adapt the design for indoor spaces that would typically use central air conditioning,” he added.

Beyond the energy savings, technologies like the Cold Tube have a great future, says project co-lead Forrest Meggers, an assistant professor at Princeton’s school of architecture and the Andlinger Center for Energy and the Environment.

Meggers noted, “Because the Cold Tube works independently of indoor air temperature and humidity, keeping windows open in our increasingly hot summers while still feeling comfortable becomes possible. The Cold Tube can offer relief in different regions, from North American homes and offices that currently rely on standard HVAC systems to developing economies that foresee significant need for cooling in the coming half-century.”

Adam Rysanek said there’s another aspect of the Cold Tube that is particularly relevant in 2020, “The COVID-19 pandemic has brought to the public’s awareness how sensitive our health is to the quality of the air we breathe indoors. Specifically, we know that some of the safest spaces in this ‘new normal’ are outdoor spaces. As the climate changes and air conditioning becomes more of a global necessity than a luxury, we need to be prepared with alternatives that are not only better for the environment, but also our health. The idea of staying cool with the windows open feels a lot more valuable today than it did six months ago.”

The team is currently using the data collected in Singapore to update their projections of the Cold Tube’s effectiveness in indoor spaces globally. They plan to demonstrate a commercially viable version of the technology by 2022.

This sounds like a truly great idea. Assuming the airtight humidity-repelling membrane works across a very wide spectrum of conditions and lasts a long long time, the technology could become a part of a “new normal” across the globe.

And it would be so very welcome indeed. Next up, lets hope there is a muggy humidity canceling system coming from somewhere.

An international team of physicists including Jennifer Cano, PhD, of Stony Brook University, has created a new material layered by two structures, forming a superlattice, that at a high temperature is a super-efficient insulator conducting current without dissipation and lost energy.

The finding, detailed in a paper published in Nature Physics, could be the basis of research leading to new, better energy efficient electrical conductors.

Atomically resolved STEM on a high magnification scale. The atomic positions of Bi (green), Te(blue), and Mn (yellow) in the SL and QL are indicated. Image Credit: Stony Brook University. Click image for the largest view.

The material is created and developed in a laboratory chamber. Over time atoms attach to it and the material appears to grow – similar to the way rock candy is formed. Surprisingly, it forms a novel ordered superlattice, which the researchers test for quantized electrical transport.

The research centers around the Quantum Anomalous Hall Effect (QAHE), which describes an insulator that conducts dissipationless current in discrete channels on its surfaces. Because QAHE current does not lose energy as it travels, it is similar to a superconducting current and has the potential if industrialized to improve energy-efficient technologies.

Cano, Assistant Professor in the Department of Physics and Astronomy in the College of Arts and Sciences at Stony Brook University and also an Affiliate Associate Research Scientist at the Flatiron Institute’s Center for Computational Quantum Physics said, “The main advance of this work is a higher temperature QAHE in a superlattice, and we show that this superlattice is highly tunable through electron irradiation and thermal vacancy distribution, thus presenting a tunable and more robust platform for the QAHE.”

Cano and colleagues said they can advance this platform to other topological magnets. The ultimate goal would be to help transform future quantum electronics with the material.

The collaborative research is being led by City College of New York under the direction of Lia Krusin-Elbaum, PhD.

To review in simpler terms, the material is an insulator. Except that its surface can be made to form conduction paths, something like a semiconductor does in today’s technology building computer processors and memory chips. “Conductor” suggest wires, but there isn’t a suggestion here for transmissions lines or motor windings.

Those big data centers consume lots of power. Semiconductors generate significant heat while operating. This technology may someday cut that energy requirement in a huge way. Still, the technology has a very long way to go.

The news is the Quantum Anomalous Hall Effect can be made to work and work well. The research is a step into a new field now. Where this could take technologies that can take advantage is anybody’s guess now.


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