Tag: hydrogen

Toward greener production of hydrogen

Toward greener production of hydrogen

McGill researchers improve efficiency, stability of electrolysis process

Hydrogen fuel could be an important part of the clean energy revolution. But it faces some challenges. Most hydrogen today is made from natural gas using a process called steam methane reforming, which produces lots of carbon dioxide.

“While hydrogen is a clean fuel, the way that we make it isn’t clean at all,” says Hamed Heidarpour, a PhD student in Ali Seifitokaldani’s Electrocatalysis Lab at McGill University in Montreal.

Creating hydrogen from water through electrolysis, on the other hand, generates no CO2. But the method is inefficient, expensive, and requires a lot of electricity, which doesn’t always come from renewable sources.

Heidarpour and his colleagues found a way to make the process more energy-efficient and stable – and thus more viable for real-world industrial applications.

Their version of electrolysis combines water with hydroxymethylfurfural (HMF), an organic compound that can be produced by breaking down non-food plant materials such as pulp and paper residue. In traditional electrolysis, hydrogen is produced at the cathode, and oxygen at the anode. But the reaction – called the oxygen evolution reaction (OER) — is slow and takes a lot of energy. By including an organic molecule like HMF, the OER is replaced with the more energy-efficient oxidation of HMF, which has the bonus of also producing hydrogen.

“At the same energy input, we can double the production of hydrogen,” he says.

Heidarpour focused on designing a better catalyst to make the HMF oxidation reaction even more energy-efficient, and more commercially viable. The normal copper catalyst does not last long enough for long-term use, so the team added a protective layer of chromium to stabilize it. Their research was published in Chemical Engineering Journal.

Read more on the CLS website

Image: Hamed in the lab

Credit: CLS

Critical raw materials from electrolysers back into the cycle

Critical raw materials from electrolysers back into the cycle

Researchers succeed in recycling functional materials for hydrogen production

Hydrogen plays a central role in the energy transition. The gas is mainly produced with the help of electrolysers. This process requires critical raw materials such as platinum group metals, rare earths or nickel as catalysts. Researchers at the Helmholtz Institute Freiberg for Resource Technology (HIF), an institute of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), have now been able to recover these functional materials using innovative flotation processes and liquid-liquid particle separation, thus returning them to the material cycle. The research is part of the H2Giga lead project of the German Federal Ministry of Education and Research (BMBF), which is investigating the longevity and recyclability of hydrogen electrolysers.

Hydrogen is considered a clean energy source that can help reduce CO2 emissions. The focus here is particularly on green hydrogen, which is produced through the electrolysis of water using renewable energies such as wind and solar power. Hydrogen is used in industry, for example as a raw material for the production of chemicals and steel, as well as in the transport sector, where it is used as a fuel for fuel cell vehicles. Hydrogen can also be used to store surplus energy from renewable sources, making it an important building block for a sustainable and climate-friendly energy future. According to the national hydrogen strategy, Germany is expected to need 95 to 135 terawatt hours of hydrogen in 2030.

Various processes can be used to produce hydrogen – one is water electrolysis: water is broken down into hydrogen and oxygen using an electric current. The catalysts in the electrolyser consist of critical metals, the so-called functional materials. Proton exchange membrane electrolysers (PEM) mainly use metals from the platinum group, such as platinum, iridium and palladium. High-temperature electrolysers use rare earths and nickel. These critical raw materials need to be secured. This is a project that HIF researchers are working on under the leadership of the TU Bergakademie Freiberg in the ReNaRe project.

ReNaRe stands for Recycling – Sustainable Resource Utilization and is part of the H2Giga flagship project. To implement the national hydrogen strategy, the BMBF has set up three flagship projects for Germany’s entry into the hydrogen economy. One of these is H2Giga, which focuses on the series production of hydrogen electrolysers. ReNaRe concentrates on the end of life of electrolysers in order to return the materials used, and in particular the critical metals, to the material cycle.

“We are involved in the recycling of PEM and high-temperature electrolysers, as they are easy to dismantle. We use ultra-fine particle separation techniques to recover the functional materials. This is because the critical anode and cathode materials are present as fine particles. Their size corresponds to approximately one hundredth of a human hair. Liquid-liquid particle separation and agglomeration flotation have proven to be suitable for separating the functional materials. The extraction of ultrafine particles uses a sustainable solvent-water circulation system for the effective separation of hydrophobic, i.e. water-repellent cathode catalysts and hydrophilic (water-attracting) anode catalysts. The complementary agglomeration flotation uses an innovative, sustainable hydrophobic binder to enable agglomeration of the particles into a uniform mass. The binder is based on a special emulsion technology, i.e. an oil-water mixture with a very high water content, which selectively agglomerates hydrophobic ultrafine particles. This enables the separation of hydrophilic ultrafine particles by adhesion to gas bubbles and discharge in the foam,” says Sohyun Ahn, PhD student at the HIF, describing the procedure. “With both processes, we were able to recover up to 90 percent of the critical functional materials and return them to the material cycle. An important step towards operating hydrogen electrolysis economically and sustainably.”

Read more on HZDR website

Image: Water drop (black) above a hydrophobic particle (grey are at the bottom)

Source: Ahn, Sohyun

New material for efficient separation of Deuterium at elevated Temperatures

New material for efficient separation of Deuterium at elevated Temperatures

A novel porous material capable of separating deuterium (D2) from hydrogen (H2) at a temperature of 120 K has been introduced. Notably, this temperature exceeds the liquefaction point of natural gas, thus facilitating large-scale industrial applications. This advancement presents an attractive pathway for the economical production of D2 by leveraging the existing infrastructure of liquefied natural gas (LNG) production pipelines. The research conducted by Ulsan National Institute of Science & Technology (UNIST), Korea, Helmholtz-Zentrum Berlin, Heinz Maier Leibnitz Zentrum (MLZ), and Soongsil University, Korea, has been published in Nature Communications.

Deuterium, a stable isotope of hydrogen, plays a critical role in enhancing the durability and luminous efficiency of semiconductors and display devices, as well as serving as a fusion fuel in energy production. However, the increasing demand for D2 presents challenges in its production, primarily due to the need to separate from hydrogen through a cryogenic distillation process conducted at temperatures as low as 20 K (-253°C). While research has explored the use of metal-organic frameworks (MOFs) for D2 separation, their efficiency diminishes significantly at elevated temperatures.

In this study, the research team presented a copper-based zeolite imidazolate framework (Cu-ZIF-gis), which shows exceptional D2 separation performance, even at 120 K (-153℃). While typical MOFs operate effectively at around 23 K (-250℃), their performance decreases sharply as temperatures approach 77 K (-196℃). However, the newly developed Cu-based MOF demonstrates a significant advantage in maintaining its effectiveness at higher temperatures.

For the first time, the research team identified that the superior performance of this material results from the increased expansion of its lattice as the temperature rises. At cryogenic temperatures, the pores of the developed MOF are smaller than H2 molecules, thereby inhibiting their passage. However, as the temperature increases, the lattice expands, leading to an increase in pore size. This enlargement facilitates the passage of gases through the pores, thereby enabling the separation of H2 and D2 via the quantum sieving effect, wherein heavier molecules traverse the pores more efficiently at lower temperatures.

Confirmatory in-situ X-ray diffraction (XRD) and quasi-elastic neutron scattering (QENS) experiments, conducted at the Institut Laue-Langevin (ILL) in Grenoble, France, by the joint team from UNIST, HZB and MLZ, confirmed the expansion of the lattice framework with increasing temperature, as well as the difference in isotope diffusivity even at elevated temperatures. Additionally, the analysis from the Thermal Desorption Spectroscopy (TDS) experiments indicated stable D2 separation at elevated temperatures.

Read more on HZB website

Image: The crystal structure of Cu-ZIF-gis that shows cylindrical straight channels along the c-axis. The pores were calculated with Connolly surfaces with a probe of 1.1 Å. (Cu, orange; N, blue; C, gray; O, magenta; H, white).

Credit: Minji Jung / Department of Chemistry, UNIST

Advancing hydrogen as a replacement for carbon fuels

Advancing hydrogen as a replacement for carbon fuels

While the notion of using hydrogen for energy has been around since Sir William Grove first invented the fuel cell in 1838, the idea started to get more traction after the first use of fuel cells in space for NASA’s 1965 Gemini V mission.

More recently, researchers like Tess Seip, a PhD candidate in the Mechanical and Industrial Engineering Department at the University of Toronto (UToronto), have been investigating hydrogen as a green energy source to mitigate carbon emissions.

Seip and a team led by Dr. Aimy Bazylak are working to improve the efficiency of a device that uses electricity—preferably from solar and wind sources—to convert water into hydrogen and oxygen gases, which can then be stored and used for energy. The device is called a polymer electrolyte membrane water electrolyzer, or PEMWE for short.

The UToronto team was focused on a specific layer inside the PEMWE, called the porous transport layer (PTL), which controls the flow of water inside. Water passes through the PTL before it reaches a catalyst layer, which splits the water molecule.

However, the reaction—known as electrolysis—can cause excess gas to accumulate, which prevents water from reaching the catalyst. Seip and her colleagues were testing a new design they developed, which has extra channels in it, to improve water flow. Better water flow means less energy is needed to drive the process.

With the help of the Canadian Light Source (CLS) at the University of Saskatchewan, the team found that their simple modification did in fact improve the efficiency of a PEMWE.

Seip and her colleagues were particularly interested to see if there were changes in membrane thickness and PTL hydration. “If it’s not hydrated, it slows the reaction rate and reduces the efficiency,” says Seip.

The ultra bright light produced by the CLS synchrotron was critical for their work: “The BMIT beamline at the CLS has a resolution of around 6.5 microns per pixel, so this lets us characterize these microscopic changes in the membrane,” says Seip. For reference, the typical human hair is 65 microns thick. “The most important factor is that we are able to do this while the cell is operating.”

Read more on CLS website

Image: The research team at the BMIT-ID beamline at the Canadian Light Source. L-R: Tess Seip, Lijun Zhu, Chaeyoung Tina Ham, Dr. Alexandre Tugirumubano, and Prof. Aimy Bazylak.

Hydrogen: Breakthrough in alkaline membrane electrolysers

Hydrogen: Breakthrough in alkaline membrane electrolysers

A team from the Technical University of Berlin, HZB, IMTEK (University of Freiburg) and Siemens Energy has developed a highly efficient alkaline membrane electrolyser that approaches the performance of established PEM electrolysers. What makes this achievement remarkable is the use of inexpensive nickel compounds for the anode catalyst, replacing costly and rare iridium. At BESSY II, the team was able to elucidate the catalytic processes in detail using operando measurements, and a theory team (USA, Singapore) provided a consistent molecular description. In Freiburg, prototype cells were built using a new coating process and tested in operation. The results have been published in the prestigious journal Nature Catalysis.

Hydrogen will play a major role in the energy system of the future, as an energy storage medium, a fuel and valuable raw material for the chemical industry. Hydrogen can be produced by electrolysis of water in a virtually climate-neutral way, provided this is done with electricity from solar or wind power. Scale-up efforts for a green hydrogen economy are currently largely dominated by two systems: proton-conducting membrane electrolysis (PEM) and classic liquid alkaline electrolysis. AEM electrolysers combine the advantages of both systems and, for example, do not require rare precious metals such as iridium.

Alkaline Membrane (AEM) Electrolysers without Iridium

Now, research teams from TU Berlin and HZB, together with the Department of Microsystems Engineering (IMTEK) at the University of Freiburg and Siemens Energy, have presented the first AEM electrolyser that produces hydrogen almost as efficiently as a PEM electrolyser. Instead of iridium, they used nickel double hydroxide compounds with iron, cobalt or manganese and developed a process to coat them directly onto an alkaline ion exchange membrane.

Read more on HZB website

Image:The AEM water electrolyser cell works with a newly developed membrane electrode (MEA) that is directly coated with a nickel-based anode catalyst. Its molecular mode of action has been elucidated, and the AEM cell has proven to be almost as powerful as a conventional PEM cell with iridium catalyst.

Credit: Flo Force Fotografie, Hahn-Schickard & IMTEK Universität Freiburg

Relationship between enhanced electrochemical performance and partially amorphous material structure

Relationship between enhanced electrochemical performance and partially amorphous material structure

A research team under the leadership of Sebastian Molin D.Sc., from the Faculty of Electronics, Telecommunications and Informatics at Gdańsk University of Technology (as part of a joint project with scientists from the Warsaw University of Technology and Kaunas University of Technology), in collaboration with ASTRA beamline scientists, characterised the perovskite oxide La0.6Sr)0.4CoO3-δ as an oxygen electrode for solid oxide fuel cell technology. This material showed enhanced electrochemical efficiency for the reduction of oxygen when present in a partially amorphous form. Using X-ray absorption spectroscopy (XAS) at the SOLARIS synchrotron. The results of the study have been published in the journal of Applied Surface Science, published by Elsevier.

Read more on SOLARIS website

Image: Wavelet Transform calculated from EXAFS for La0.6Sr0.4CoO3-δ annealed at range 400 °C–700 °C. 

The fascinating future of metal tellurate materials

The fascinating future of metal tellurate materials

Scientists have determined the structure of a new material with potential to be used in solar energy, batteries, and splitting water to produce hydrogen.

The physical properties and crystal structures of most tellurate materials were only discovered during the last two decades, but they have tantalizing properties. For example, they respond to light in a way very similar to current solar materials.

“This could be one material for all applications,” says University of Oulu scientist Dr. Harishchandra Singh. “But they are new and very little is known in the literature. We are am trying to explore all its unexplored and hidden properties.”

Identifying the structure of new materials is often the first step to unlocking their potential for applications. The international team, led by Matthias Weil (Vienna University of Technology) and Dr. Singh, successfully created a single crystal of a metal tellurate compound, making it possible to precisely define its structure with better accuracy than ever before.

The pair used the Canadian Light Source (CLS) at the University of Saskatchewan to understand how the material works under real world conditions. A longtime user of the facility, Singh knew that the Brockhouse beamline could help confirm the structural details they had uncovered.

Read more on CLS website

X-rays look at nuclear fuel cladding with new detail

X-rays look at nuclear fuel cladding with new detail

Micro-beam measurements at the Swiss Light Source SLS have enabled insights into the crystal structure of hydrides that promote cracks in nuclear fuel cladding. This fundamental knowledge of the material properties of cladding will help assess safety during storage.

For over seventy years, zirconium alloys have been used as cladding for nuclear fuel rods. This cladding provides a structural support for the nuclear fuel pellets and an initial barrier to stop fission products escaping into the reactor water during operation. During its long history, which includes extensive research and development advances, reactor type zirconium alloys have proved themselves as an extremely successful material for this application.

Yet they have a well-known nemesis: hydrogen. When submerged in water during operation in a reactor, at the hot surface of the fuel rod water molecules split into hydrogen and oxygen. Some of this hydrogen then diffuses into the cladding. It makes its way through the cladding until – when the concentration and conditions are right – it precipitates to form chemical compounds known as zirconium-hydrides. These hydrides make the material brittle and prone to cracking. Now, using the Swiss Light Source SLS, researchers were able to shed new light on the interplay between cracking and hydride formation.

Using a technique called synchrotron micro-beam X-ray diffraction, the researchers could study the structure of hydrides during the growth of cracks in fuel cladding at a new level of detail. “Through thermomechanical tests, we could control extremely slow crack propagations. Discovering at such high spatial resolution which hydride formations actually occurred made all the challenges of the material preparation worthwhile,” says study first author, Aaron Colldeweih who designed the thermomechanical testing procedure as part of his PhD project at PSI.

One of the things they discovered was that an unexpected type of hydride was present at the crack tip. This type of hydride, known as gamma-hydride has a slightly different crystal structure and stoichiometry to the type more commonly present, known as delta-hydride, “There has been a lot of discussion about gamma-hydrides: whether they are stable and whether they exist at all. Here we could show that with certain applied stresses you create gamma-hydrides that are stable,” says Johannes Bertsch, who leads the Nuclear Fuels Group in the Laboratory of Nuclear Materials at PSI.

Read more on the PSI website

Image: Malgorzata Makowska, scientist at the MicroXAS beamline of the SLS, carefully positions a standard material for setup calibration on the sample manipulator in front of the X-ray beam.

Credit: Paul Scherrer Institute / Mahir Dzambegovic