Tag: green hydrogen

Hydrogen storage in MXene: It all depends on diffusion processes

Hydrogen storage in MXene: It all depends on diffusion processes

Two-dimensional (2D) materials such as MXene are of great interest for hydrogen storage. An expert from HZB has investigated the diffusion of hydrogen in MXene using density functional theory. This modelling provides valuable insights into the key diffusion mechanisms and hydrogen’s interaction with Ti₃C₂ MXene, offering a solid foundation for further experimental research.

Hydrogen is an energy carrier that can be produced in a climate-friendly way by electrolysis of water using ‘green’ electricity. However, storing hydrogen is not that easy. MXene could be a promising solution. MXene are compounds of metal and nitrogen or carbon that form a two-dimensional hexagonal structure, giving them special physical and chemical properties. Atoms and molecules, such as hydrogen, can be stored both in and between the 2D layers. ‘However, we know that hydrogen atoms and even molecules form complex bonds in MXene and on its surfaces,’ says Prof. Dr. Norbert Nickel, a physicist at HZB. When storing hydrogen, it is also important that the hydrogen bound in the material can be released when needed.

Previous neutron scattering experiments have shown that hydrogen can be stored in the MXene material Ti3C2. However, in 2024, Nickel calculated exactly how the hydrogen orbitals interact with the titanium and carbon orbitals using density functional theory. These results shed light on the nature of hydrogen’s chemical bonding and how temperature affects the diffusion process (see Annalen der Physik, 536, 2400011 (2024)). Nevertheless, quantum mechanical calculations of the interactions between hydrogen atoms and molecules with Ti₃C₂ show that the simple model of chemical bonding is insufficient to describe hydrogen’s bonding properties.

Recently Nickel analysed the chemical orbitals in more detail: the calculations showed that interstitial hydrogen atoms and molecules form s-like bonds with neighbouring titanium atoms and s-p hybrid orbitals with neighbouring carbon atoms.

Read more on HZB website

Image: Schematic representation of the Ti3C2 crystal lattice with hydrogen and the associated bonding orbitals. Left: normal to the c-axis; right: perpendicular to the c-axis.

Credit: N. Nickel / HZB

Green hydrogen: A cage structured material transforms into a performant catalyst

Green hydrogen: A cage structured material transforms into a performant catalyst

Clathrates are characterised by a complex cage structure that provides space for guest ions too. Now, for the first time, a team has investigated the suitability of clathrates as catalysts for electrolytic hydrogen production with impressive results: the clathrate sample was even more efficient and robust than currently used nickel-based catalysts. They also found a reason for this enhanced performance. Measurements at BESSY II showed that the clathrates undergo structural changes during the catalytic reaction: the three-dimensional cage structure decays into ultra-thin nanosheets that allow maximum contact with active catalytic centres. The study has been published in the journal ‘Angewandte Chemie’.

Hydrogen can be produced by electrolysis of water. If the electrical energy required for this process comes from renewable sources, this hydrogen is even carbon neutral. This ‘green’ hydrogen is seen as an important building block for the energy system of the future and is also needed in large quantities as a raw material for the chemical industry. Two reactions are crucial in electrolysis: hydrogen evolution at the cathode and oxygen evolution at the anode (OER). However, the oxygen evolution reaction in particular slows down the desired process. To speed up hydrogen production, more efficient and robust catalysts for the OER process need to be developed.

Clathrates, a structure build of cages

Currently, nickel-based compounds are considered to be good and inexpensive catalysts for the alkaline oxygen evolution reaction. This is where Dr. Prashanth Menezes and his team come in. ‘The contact between the active nickel centres and the electrolyte plays a crucial role in the efficiency of a catalyst,’ says the chemist. In conventional nickel compounds, this surface area is limited. ‘We therefore wanted to test whether nickel-containing samples from the fascinating class of materials known as clathrates could be used as catalysts’.

The materials are made of Ba8Ni6Ge40 and were produced at the Technical University of Munich. Like all clathrates, they are characterised by a complex crystalline structure of polyhedral cages, in this case, formed by germanium and nickel, enclosing barium. This structure gives clathrates special properties that make them interesting as thermoelectrics, superconductors or battery electrodes. However, until now, no research group had considered of investigating clathrates as electrocatalysts.

Read more on HZB website

Image: The illustration shows schematically how nanothin sheets of nickel compounds are released from the clathrate structure, providing an extremely large surface area for the oxygen evolution reaction. 

Credit: Hongyuan Yang/HZB/TUB

A faster route to green hydrogen

A faster route to green hydrogen

Acidic conditions are a challenge. If you want to produce hydrogen by electrolysis and use a low-cost catalyst such as cobalt, the process doesn’t function as well if the aqueous environment is acidic – working in alkaline conditions is easier. Researchers at the Paul Scherrer Institute PSI have now discovered the reason for this: the surface of the catalyst changes with the pH value of the environment. Their study, published in the journal Nature Chemistry, provides important clues to enable efficient and cost-effective production of hydrogen for the energy transition in the future.

The simplest and most environmentally friendly method for producing hydrogen is electrolysis: with an electric current, water (H2O) is split into its components, hydrogen (H2 ) and oxygen (O2). Oxygen is produced at the positive pole, the anode; hydrogen is produced at the negative pole, the cathode. Water splitting can be carried out in an alkaline environment (pH>7), an acidic one (pH<7), or a neutral one (pH=7). Different types of electrolysers operate at different pH values, that is, in different aqueous environments.

In splitting water, the formation of oxygen is the step that requires the most energy, effectively the bottleneck of the reaction. To make it possible to do this more efficiently and cost-effectively, catalysts such as the metal cobalt are used. However, electrolysis with cobalt only works satisfactorily in an alkaline environment; the reason for this was previously unknown.

A PSI research group in the Center for Energy and Environmental Sciences have now found out the cause: depending on the pH value, the catalyst’s surface changes. In acidic conditions, active sites where oxygen can be produced require more energy to form – as a result, electrolysis becomes slow and uneconomical. “We assume that this is the case not only with cobalt, but also with other metals that likewise perform less well in acidic conditions – such as manganese, iron, and nickel,” says Jinzhen Huang, a postdoctoral researcher in Emiliana Fabbri’s and Thomas Schmidt’s research group and first author of the study.

Cobalt as a low-cost alternative

At present, the noble metals iridium and ruthenium are usually used as catalysts for splitting water. Their activity changes only slightly depending on the pH value and therefore also work well in acidic environments. However, cobalt and other so-called transition metals are significantly cheaper and more abundant on Earth, which makes them particularly attractive for large-scale applications. “Replacing the noble metals with cobalt and other lower-cost metals is a major challenge,” Emiliana Fabbri explains. “Our findings are important steps on the way to that goal.”

Read more on PSI website

Image: Close-up of a glass vial containing a cobalt-based catalyst powder, captured in the lab at the Paul Scherrer Institute PSI. Researchers at the PSI Center for Energy and Environmental Sciences have discovered why this catalyst performs more efficiently in alkaline environments during hydrogen production.

Credit: Paul Scherrer Institute PSI/Mahir Dzambegovic

Technology Development for Producing Nearly Commercializable CO2-Free Green Hydrogen

Technology Development for Producing Nearly Commercializable CO2-Free Green Hydrogen

This study proposes a photo-electrode material technology that may significantly change the development of photo-electrochemical hydrogen production technology. With this study, it is expected that hydrogen production using photo-electrodes at a commercial level will be possible soon.

Hydrogen is an eco-friendly energy source that reduces greenhouse gases and fine dust. It is essential for building a clean and safe society. Currently, hydrogen production relies on utilizing the by-product hydrogen from petrochemical processes and extracting from natural gas. However, these production methods generate CO2, creating an ironic situation of contributing to global warming while aiming for a clean Earth.

The commercialization of solar-based production technology is urgently needed to address this issue. The U.S. Department of Energy (DOE) set specific goals for expanding clean hydrogen production in the “US National Clean Hydrogen Strategy and Roadmap” released in June 2023. Also, it established targets for commercializing solar-based hydrogen production technology at the level of a solar-to-hydrogen (STH) conversion efficiency of over 10 %, stability for over 1000 hours, and a PEC (photo-electrochemical) H2 system cost of $ 2-4 per kilogram. Various research and investments are underway to achieve these goals.

Hydrogen (H2) production requires photo-electrodes with high PEC activity and durability. However, surface defects, photo-corrosion instability, and especially instability at high potentials degrade PEC performance and stability. In this study, we introduced an HfO2 protective layer and a NiPt single-atom catalyst to improve the surface of a BiVO4 photoelectrode, classified as a low-cost material, and controlled strong corrosivity, achieving a high stability of over 800 hours. This was evaluated under one-sun solar light (100 mW/cm²). This study has significant implications as it is the first demonstration of long-term performance in the world. Furthermore, we achieved a solar-to-hydrogen conversion efficiency of 6.0 % of the self-driven photo-electrochemical water splitting device based on the BiVO4 photoelectrode, which is significant as it is approximately 90 % of the theoretical efficiency of the BiVO4 material.

Read more on PAL website

Green hydrogen: MXenes shows talent as catalyst for oxygen evolution

Green hydrogen: MXenes shows talent as catalyst for oxygen evolution

The MXene class of materials has many talents. An international team led by HZB chemist Michelle Browne has now demonstrated that MXenes, properly functionalised, are excellent catalysts for the oxygen evolution reaction in electrolytic water splitting. They are more stable and efficient than the best metal oxide catalysts currently available. The team is now extensively characterising these MXene catalysts for water splitting at the Berlin X-ray source BESSY II and Soleil Synchrotron in France.

Green hydrogen is seen as one of the energy storage solutions of the future. The gas can be produced in a climate-neutral way using electricity from the sun or wind by electrolytic water splitting. While hydrogen molecules are produced at one electrode, oxygen molecules are formed at the other. This oxygen evolution reaction (OER) is one of the limiting factors in electrolysis. Special catalysts are needed to facilitate this reaction. Among the best candidates for OER catalysts are, for example, nickel oxides, which are inexpensive and widely available. However, they corrode quickly in the alkaline water of an electrolyser and their conductivity also leaves much to be desired. This is currently preventing the development of low-cost, high-performance electrolysers.

MXene as catalysts

A new class of materials could offer an alternative: MXenes, layered materials made of metals, such as titanium or vanadium, combined with carbon and/or nitrogen. These MXenes have a huge internal surface area that can be put to fantastic use, whether for storing charges or as catalysts.

An international team led by Dr Michelle Browne has now investigated the use of MXenes as catalysts for the oxygen evolution reaction. PhD student Bastian Schmiedecke chemically ‘functionalised’ the MXenes by docking copper and cobalt hydroxides onto their surfaces. In preliminary tests, the catalysts produced in this way proved to be significantly more efficient than the pure metal oxide compounds. What’s more, the catalysts showed no degradation and even improved efficiency in continuous operation.

Read more on HZB website

Image: The surface of a Vanadium carbide MXene has been examined by Scanning Electron Microscopy. The beautiful structures are built by cobalt copper hydroxide molecules.

Credit: B. Schmiedecke/HZB

AI finds a cheaper way to make green hydrogen

AI finds a cheaper way to make green hydrogen

Researchers at the University of Toronto are using artificial intelligence to accelerate scientific breakthroughs in the search for sustainable energy. They used the Canadian Light Source (CLS) at the University of Saskatchewan (USask) to confirm that an AI-generated “recipe” for a new catalyst offered a more efficient way to make hydrogen fuel.   

To create green hydrogen, you pass electricity that’s been generated from renewable resources between two pieces of metal in water. This causes oxygen and hydrogen gases to be released. The problem with this process is that it currently requires a lot of electricity and the metals used are rare and expensive.

“We’re talking about hundreds of millions or billions of alloy candidates, and one of them could be the right answer,” said Jehad Abed. He was part of a team that developed a computer program to significantly speed up this search. Their findings were published in the Journal of the American Chemical Society. At the time of this project, Abed was a PhD student under the supervision of Edward Sargent at the University of Toronto working alongside scientists at Carnegie Mellon University.  

Researchers are searching for the right alloy, or combination of metals, that would act as a catalyst to make this reaction more efficient and affordable. Traditionally, this search would involve trial and error in the lab, but when you are trying to find the proverbial needle in a haystack, this approach takes too much time.

The AI program the team developed took over 36,000 different metal oxide combinations and ran virtual simulations to assess which combination of ingredients might work the best. Abed then tested the program’s top candidate in the lab to see if its predictions were accurate.

The team used the CLS’s ultra-bright X-rays to analyze the catalyst’s performance during a reaction. “What we needed to do is use that very bright light at the Canadian Light Source to shine it on our material and see how the atomic arrangements would change and respond to the amount of electricity that we put in,” said Abed. The researchers also used the Advanced Photon Source at the Argonne National Laboratory in Chicago.

Read more on CLS website

Green hydrogen from direct seawater electrolysis

Green hydrogen from direct seawater electrolysis

At first glance, the plan sounds compelling: invent and develop future electrolysers capable of producing hydrogen directly from unpurified seawater. But a closer look reveals that such direct seawater electrolysers would require years of high-end research. And what is more: DSE electrolyzers are not even necessary – a simple desalination process is sufficient to prepare seawater for conventional electrolyzers. In a commentary in Joule, international experts compare the costs and benefits of the different approaches and come to a clear recommendation.

Fresh water is a limited resource; more than 96% of the world’s water is found in the oceans. If seawater could be fed directly into a future electrolyser to produce green hydrogen using renewable energy from the wind or sun, it sounds like a very good solution. Hundreds of millions of dollars in research fundingare spend for this idea and, in 2023 alone, there have been more than 500 publications (this number is growing exponentially) on direct seawater electrolysis.

No need for new development

However, a techno-economic analysis shows that this argument collapses as soon as the costs and benefits are analysed in more detail. “There is no convincing reason to develop DSE technology because there are already efficient solutions for using seawater to produce hydrogen,” says Dr Jan Niklas Hausmann, electrolysis researcher at HZB and lead author of the Joule commentary. International experts from various disciplines from renowned research institutions such as Yale University, universities in Canada, Germany and HZB contributed to the commentary.

Proven methods work

It is already possible to use seawater to produce hydrogen. Proven processes such as reverse osmosis can be used to purify seawater for “normal”, commercially available electrolysers. From a thermodynamic point of view, the purification of seawater needs only 0.03% of the energy required for its electrolysis. This is also reflected in the current cost: purifying seawater to produce one kilogram of hydrogen costs less than two cents. However, one kilogram of hydrogen costs 13.85 euros at German filling stations.

Read more on HZB website

Green hydrogen: Perovskite oxide catalysts analysed in an X-ray beam

Green hydrogen: Perovskite oxide catalysts analysed in an X-ray beam

The production of green hydrogen requires catalysts that control the process of splitting water into oxygen and hydrogen. However, the structure of the catalyst changes under electrical tension, which also influences the catalytic activity. A team from the universities of Duisburg-Essen and Twente has investigated at BESSY II and elsewhere how the transformation of surfaces in perovskite oxide catalysts controls the activity of the oxygen evolution reaction.

In a climate-neutral energy system of the future, the sun and wind will be the main sources of electricity. Some of the “green” electricity can be used for the electrolytic splitting of water to produce “green” hydrogen. Hydrogen is an efficient energy storage medium and a valuable raw material for industry. Catalysts are used in electrolysis to accelerate the desired reaction and make the process more efficient. Different catalysts are used for hydrogen separation than for oxygen evolution, but both are necessary.

Perovskite oxide catalysts: inexpensive and with great potential

An interdisciplinary and international group of scientists from the University of Essen-Duisburg, the University of Twente, Forschungszentrum Jülich and HZB has now investigated the class of perovskite oxide catalysts for the oxygen evolution reaction in detail. Perovskite oxide catalysts have been significantly further developed in recent years, they are inexpensive and have the potential for further increases in catalytic efficiency. However, within a short time, changes appear on the surfaces of these materials which reduce the catalytic effect.

Read more on the HZB website

Image: Schematic side view of the transformed layer (light grey) on top of the perovskite film (green) grown on a substate (brown). (right) zoom-in of the side view of the transfromed layer together with spin density at the Ni sites from the density functional theory calculations.

Credit: © UDE/AG Pentcheva

Groundbreaking advancements in net-zero technology

Groundbreaking advancements in net-zero technology

A transnational collaborative research team, comprising Jeng-Lung Chen, Assistant Scientist, Yu-Chun Chuang, Associate Scientist, and Chung-Kai Chang, Research Assistant from the National Synchrotron Radiation Research Center (NSRRC) under the purview of the National Science and Technology Council, in partnership with Dr. Lu-Ning Chen, Professor Gabor A. Somorjai, and Dr. Ji Su from the Lawrence Berkeley National Laboratory in California, USA, has dedicated three years to pioneering global advancements in the field of green hydrogen production. Their groundbreaking work centers around the development of a methane pyrolysis catalyst, known as the “nickel-molybdenum-bismuth liquid alloy (NiMo-Bi),” which exhibits high hydrogen production efficiency, excellent stability, and low energy consumption. This study explored the electrostatic charge distribution on the active nickel sites in the molten state, demonstrating the NiMo-Bi liquid alloy’s capability to effectively mitigate the cage effect caused by bismuth. This mitigation facilitates the effective flow of methane to active nickel sites, resulting in efficient hydrogen generation. This outstanding discovery was published in the respected international journal Science on August 25, 2023, emerging as a pivotal driving force for advancing the transition to a net-zero future.  

The U.S. research team initially integrated molybdenum into the nickel-bismuth catalyst, resulting in the creation of an innovative catalyst known as NiMo-Bi liquid alloy. Meanwhile, NSRRC scientists engineered an experimental setup tailored for in-situ high-temperature gas-phase reactions. Harnessing the capabilities of the “Quick X-ray Absorption Spectroscopy Beamline” and the “High Resolution Powder X-ray Diffraction Beamline” at the Taiwan Photon Source (TPS), the team validated the catalyst’s efficacy by significantly lowering methane pyrolysis temperatures to values as low as 450 °C. They also showed that at an elevated temperature of 800 °C, the selectivity of converting methane into hydrogen reached 100%, maintaining this optimal level for a stable period of 120 hours. This achievement marks a nearly 37-fold improvement in hydrogen production efficiency compared to previous methods. Concurrently, the optimal pyrolysis temperature was significantly reduced from 1065 degrees Celsius to 800 degrees Celsius, resulting in a significant reduction in the energy requirements of the conversion process.

Read more on the NSRRC website

Image: Quick X-ray Absorption Spectroscopy Beamline

BESSY II: Surface analysis of catalyst particles in aqueous solutions

BESSY II: Surface analysis of catalyst particles in aqueous solutions

In a special issue on the liquid jet method, a team reports on reactions of water molecules on the surfaces of metal oxide particles. The results are relevant for the development of efficient photoelectrodes for the production of green hydrogen.

Green hydrogen can be produced directly in a photoelectrochemical cell, splitting water with solar energy. However, this requires the development of super-efficient photoelectrodes that need to combine many talents at the same time: They must be excellent at converting sunlight into electricity, remain stable in acidic or basic water, act as catalysts to promote the splitting of water into hydrogen and oxygen, and be cheap, abundant and non-toxic. The large material class of metal oxides comes into question. However, it is difficult to find out what really happens at the interfaces between the solid metal oxide electrodes and the aqueous electrolyte. This is because standard X-ray analysis does not work to investigate processes on samples in liquid environments. One of the few suitable methods are experiments with a liquid jet: an extremely fine jet of liquid in which nanoparticles of metal oxide are suspended. This jet shoots through the X-ray light of BESSY II, and the interference of the evaporated molecules with the measurement data is negligible (more in the foreword to the special issue).

Dr. Robert Seidel is an expert on this liquid jet method, which is the subject of a special issue of Accounts of Chemical Research. He was invited to be the guest-editor of the issue and to report also on new experiments at BESSY II that he conducted with Dr. Hebatallah Ali and Dr. Bernd Winter from the Fritz Haber Institute.

They investigated two important model systems for photoelectrodes: Nanoparticles of iron oxide (hematite, α-Fe2O3, and anatase (titanium oxide or TiO2) in aqueous electrolytes with different pH values. Hematite and anatase in suspension are photocatalytic model systems. They are ideal for studying the solid/electrolyte interface at the molecular level and for exploring the chemical reactions at electrode-electrolyte interfaces.

“We used resonant photoelectron spectroscopy (PES) to identify the characteristic fingerprints of different reactions. This allowed us to reconstruct which reaction products are formed under different conditions, particularly as a function of pH.” The key question: How do the water molecules react with or on the nanoparticle surfaces?

In fact, how acidic or how basic an electrolyte is makes a big difference, Seidel noted. “At low pH, the water molecules on the surface of hematite tend to split. This is not the case with anatase, where water molecules are adsorbed on the surface of the TiO2 nanoparticles,” says Seidel. A basic pH value is required for water molecules to break down on the anatase nanoparticles. “Such insights into surface interactions with water molecules are only possible with this liquid-jet method,” says Seidel.

The spectra also revealed ultra-fast electron transitions between the metal oxide and the (split) water molecules on the surface. The results provide insights into the first steps of water dissociation and help to clarify the mechanisms of light-induced water splitting on metal oxide surfaces.

Read more on this story here

Image: The microjet is a fast-flowing stream of liquid so narrow that it produces only an extremely dilute vapour cloud. Photons and particles can reach and leave the surface of the jet without colliding with the vapour molecules.

Electrocatalysis – Iron and Cobalt Oxyhydroxides examined

Electrocatalysis – Iron and Cobalt Oxyhydroxides examined

A team led by Dr. Prashanth W. Menezes (HZB/TU-Berlin) has now gained insights into the chemistry of one of the most active anode catalysts for green hydrogen production. They examined a series of Cobalt-Iron Oxyhydroxides at BESSY II and were able to determine the oxidation states of the active elements in different configurations as well as to unveil the geometrical structure of the active sites. Their results might contribute to the knowledge based design of new highly efficient and low cost catalytical active materials.

Very soon, we need to become fossil free, not only in the energy sector, but as well in industry. Hydrocarbons or other raw chemicals can be produced in principle using renewable energy and abundant molecules such as water and carbon dioxide with the help of electrocatalytically active materials. But at the moment, those catalyst materials either consist of expensive and rare materials or lack efficiency.

Key reaction in water splitting

A team led by Dr. Prashanth W. Menezes (HZB/TU-Berlin) has now gained insights into the chemistry of one of the most active catalysts for the anodic oxygen evolution reaction (OER), which is a key reaction to supply electrons for the hydrogen evolution reaction (HER) in water splitting. The hydrogen can then be processed into further chemical compounds, e.g., hydrocarbons. Additionally, in the direct electrocatalytic carbon dioxide reduction to alcohols or hydrocarbons, the OER also plays a central role.

Read more on the HZB website

Image: LiFex-1Cox Borophosphates have been used as inexpensive anodes for the production of green hydrogen. Their dynamic restructuring during OER as well as their catalytically active structure, have been elucidated via  X-ray absorption spectroscopy.

Credit: © P. Menezes / HZB /TU Berlin

Green hydrogen: Nanostructured nickel silicide shines as a catalyst

Green hydrogen: Nanostructured nickel silicide shines as a catalyst

Electrical energy from wind or sun can be stored as chemical energy in hydrogen, an excellent fuel and energy carrier. The prerequisite for this, however, is efficient electrolysis of water with inexpensive catalysts. For the oxygen evolution reaction at the anode, nanostructured nickel silicide now promises a significant increase in efficiency. This was demonstrated by a group from the HZB, Technical University of Berlin and the Freie Universität Berlin as part of the CatLab research platform with measurements among others at BESSY II.

Electrolysis might be a familiar concept from chemistry lessons in school: Two electrodes are immersed in water and put under voltage. This voltage causes water molecules to break down into their components, and gas bubbles rise at the electrodes: Oxygen gas forms at the anode, while hydrogen bubbles form at the cathode. Electrolysis could produce hydrogen in a CO2-neutral way – as long as the required electricity is generated by fossil free energy forms such as sun or wind.

The only problem is that these reactions are not very efficient and extremely slow. To speed up the reactions, catalysts are used, based on precious and rare metals such as platinum, ruthenium or iridium. For large-scale use, however, such catalysts must consist of widely available and very cheap elements.

Read more on the HZB website

Image: Crystalline nickel silicide (left) is chemically transformed into nanostructured material with excellent catalytic properties for the electrolytic splitting of water and the production of valuable nitrile compounds. 

Credit: © P. Menezes /HZB/TU Berlin

Green hydrogen: Why do certain catalysts improve in operation?

Green hydrogen: Why do certain catalysts improve in operation?

Crystalline cobalt arsenide is a catalyst that generates oxygen during electrolytic water splitting in the production of hydrogen. The material is considered to be a model system for an important group of catalysts whose performance increases under certain conditions in the course of electrolysis. Now a HZB-team headed by Marcel Risch has observed at BESSY II how two simultaneous mechanisms are responsible for this. The catalytic activity of the individual catalysis centres decreases in the course of electrolysis, but at the same time the morphology of the catalyst layer also changes. Under favourable conditions, considerably more catalysis centres come into contact with the electrolyte as a result, so that the overall performance of the catalyst increases.

As a rule, most catalyst materials deteriorate during repeated catalytic cycles – they age. But there are also compounds that increase their performance over the course of catalysis. One example is the mineral erythrite, a mineral compound comprising cobalt and arsenic oxides with a molecular formula of (Co3(AsO4)2∙8H2O). The mineral stands out because of its purple colour. Erythrite lends itself to accelerating oxygen generation at the anode during electrolytic splitting of water into hydrogen and oxygen.

Read more in the HZB website

Image: Schematic of the electrochemical restructuring of erythrite. The fine needle-like structure melts during the conversion from a crystalline material to an amorphous one, which is porous like a Swiss cheese.

Credit: © HZB

Turning straw into gold?

Turning straw into gold?

A more profitable and eco-friendly method for turning biomass into biochemicals and green hydrogen

Many have dreamed of being able to turn straw into gold like the fabled Rumpelstiltskin. While this may not be possible in the literal sense, scientists are using sunlight to turn straw into something more valuable.

With the aid of technology from the Canadian Light Source (CLS) at the University of Saskatchewan, Canadian researchers have made important advances to use the power of the sun to convert biomass like wheat straw into hydrogen fuel and value-added biochemicals. This method is more efficient, eco-friendly and lucrative.

Producing energy from biomass, or plant material, has been studied for more than four decades, said Dr. Jinguang Hu, assistant professor at the University of Calgary (UCalgary). The two most common processes are thermo-chemical and biological, but these are still carbon intensive and are not economically feasible.

Read more on the CLS website

Image: The UCalgary team is observing a photo-reactor that is being used for a photoreforming reaction with wheat straw. Left to right: Prof. Md Golam Kibria, Dr. Adnan Khan (Research Associate), Dr. Heng Zhao (Post doctoral fellow), Prof. Jinguang Hu.

Credit: Prof. Hu and Kibria group.