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

Developing new alloys for hydrogen fuel and catalysis

An alloy is a metal that contains two or three different elements. Steel, for instance, is an alloy of iron and carbon that offers increased strength as a building material.

By mixing more elements together, scientists hope to create new and improved alloys with increased strength and improved corrosion resistance, which could help many industry sectors to reduce costs.

“The trouble is that when you try to make a traditional alloy with more than a couple of elements, the elements tend to separate from each other and clump together,” said David Morris, a PhD student in the Department of Chemistry at the Dalhousie University.

That’s why his research team is interested in alloys with five or more elements that have a highly disordered nature. This chaotic property causes the elements to disperse throughout the mixture and prevent clumping. “You can get alloys with elements that wouldn’t usually go together,” he said.

Morris and his colleagues, including Liangbing Hu’s group from the University of Maryland who synthesized the samples using a special carbothermal shock method, are investigating two alloy samples, one made of five elements and another with fifteen.

“Early experiments suggested that the five-element alloy has high catalytic activity for ammonia decomposition, a process used to make hydrogen fuel, but they potentially have all kinds of applications,” he said.

The team gathered data at the Advanced Photon Source (APS) in Illinois, thanks to the facility’s partnership with the Canadian Light Source (CLS) at the University of Saskatchewan. Using synchrotron light, Morris could analyze each element in their samples separately and spot the differences in the structures of the two alloys.

The researchers discovered that the fifteen-element alloy had some elements that showed oxidation and the length of some of the bonds between them increased. These properties, however, were not found in the five-element alloy, indicating the properties of these special alloys are highly dependent on their compositions.

“Increased oxidation means they are less stable, which could potentially increase the activity for catalysis,” said Morris. “And unusual bond lengths can change the properties and maybe make a more promising catalytic pathway.”

The group’s next step will be to try and link the changes in structure seen in this experiment to the alloys’ catalytic activity. “If we are able to find certain structural properties that are associated with a high catalytic activity, that would allow us to design more effective catalysts in the future,” said Morris.

Read more on the CLS website

Image: APS