Tag: electrolysis

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

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

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

Producing hydrogen from seawater

Producing hydrogen from seawater

McGill scientists have identified potential method for producing hydrogen from the oceans.

In her research on bone tissue engineering, Dr. Marta Cerruti has worked for years with graphene, a single sheet of carbon atoms with incredible properties – electrical conductivity and the ability to support tremendous weight. Now, her quest to improve its qualities has opened the door to a possible solution to one of the challenges of producing hydrogen from seawater.

Cerruti, a professor of materials engineering at McGill University, explained that while graphene is structurally sound, “one sheet of atoms is not something you can easily work with.” In fact, piling the sheets up results in, basically, pencil lead.

Searching for a way to make an easy-to-handle structure, Cerruti’s PhD student Yiwen Chen combined graphene with oxygen in a suspension with water to create reduced graphene oxide (GO), a porous, three-dimensional, electrically conductive scaffold. Cerruti suggested a further modification, with GO flakes stacked on the pore walls, “which allowed us to exploit another interesting property of GO – it creates a membrane that allows water through but no other molecules.”

When she canvassed her team for suggestions on how best to test the new scaffold, Gabriele Capilli, a post-doctoral fellow in her lab, suggested seawater electrolysis, a process similar to others he worked on while doing his PhD. It turns out the new GO “selective scaffold” has the potential to improve the process of producing hydrogen from the ocean. The team’s findings were published recently in the journal ACS Nano.

In conventional electrolysis, chloride ions in seawater penetrate the electrode and interact with the catalyst, creating hypochlorite ions, an unwanted byproduct that poisons the catalyst, Cerruti explained. Using X-ray phase contrast imaging at the Canadian Light Source at the University of Saskatchewan, Chen confirmed the GO scaffold had the right structure, with closed GO pores enclosing cobalt oxide nanoparticles as the catalyst. “We saw what we wanted to see.” Electrochemical tests performed in the laboratory of collaborator Thomas Szkopek (electrical engineering, McGill) confirmed the scaffold worked as expected to block unwanted ions.

Read more on the CLS website

Image: Gabriele Capilli, Marta Cerruti, and Thomas Szkopek (l to r), in their lab at McGill University.