UCLA-led study could be a step towards cheaper hydrogen-based energy

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The research group is now collaborating with Toyota Motor Corp. to develop fuel cell catalysts with possible real-world applications. (Photo: Toyota’s hydrogen fuel cell concept vehicle, 2019.)

Main takeaways:

• High cost of catalyst. Platinum is the best catalyst for hydrogen fuel cells, but its scarcity makes it expensive.
• Find alternatives. The new method quickly identifies which alloy — a less expensive combination of platinum and another metal — is likely to achieve the best results in fuel cells.
• Cut costs. High-performance alloy catalysts could eventually make hydrogen fuel cell vehicles more affordable.

A study led by UCLA researchers could help accelerate the use of hydrogen as an environmentally friendly energy source in transportation and other applications.

The team developed a method to predict the potency and stability of platinum alloys – two key indicators of how they will perform as catalysts in hydrogen fuel cells. Then, using that technique, they design and produce alloys that produce extraordinary results under conditions close to real-world use. The findings are published in the journal Nature Catalysis.

“For the sustainability of our planet, we cannot continue to live as we do, and reinventing energy is one of the main ways to change our path,” said correspondent author Yu Huang, a professor of materials science and engineering at the UCLA Samueli School. Engineering and member of the California NanoSystems Institute at UCLA. “We have fuel cell cars, but we need to make them cheaper. In this study, we found an approach that allows researchers to identify the right catalyst more quickly.”

Fuel cells generate power using oxygen from the atmosphere and hydrogen. The key step in this process is to use a catalyst to break bonds between pairs of oxygen atoms. The catalysts that work best are those that are highly active, to promote a reaction, while also being stable enough to be used over a long period of time. And for those designing fuel cells, finding the best catalyst is a huge challenge.

Platinum is the best element for the purpose, but its rarity makes the technology very expensive for large-scale adoption. Alloys combining platinum with more accessible metals or metals will reduce costs, but there has never been a practical method in the real world to quickly screen out which alloy will be the best catalyst.

As a result, technology advances so far through trial and error.

“This is a decisive step forward towards the rational design, down to the microscopic scale, of catalysts with optimal performance,” said Alessandro Fortunelli of the Italian National Research Council, correspondent author of the paper. “No one has ever devised a method, neither theoretical nor experimental, to predict the stability of a platinum alloy catalyst.”

The new method predicts the potency and stability of platinum alloy catalysts. It was developed using a combination of experiments, complex calculations and X-ray spectroscopy, which allowed the researchers to precisely identify the chemical properties.

The researchers then created catalysts that combined precise amounts of platinum, nickel, and cobalt in specific atomic structures and configurations based on their experimental sizes. They demonstrated that the alloy they designed was very active and very stable, a rare but much needed combination for fuel cell catalysts.

Huang said the method could be applied to potential catalysts that mix platinum with a subset of metals beyond nickel and cobalt.

The paper’s other correspondent authors are chemist Qingying Jia of Northeastern University and theorist William Goddard of Caltech. Huang, whose UCLA laboratory is primarily responsible for designing and testing catalysts, said collaboration with scientists and engineers at other institutions was critical to the success of the research.

“Lack of one of these partners, this job is impossible,” he said. “For a long-term, curious-driven collaboration like this, it’s important to have the right people. Each of us focused on digging deeper and trying to figure out what was going on. It also helps that it’s a fun team to work with.”

Huang Group is now collaborating with Toyota Motor Corp. to develop fuel cell catalysts with possible real-world applications.

The study’s first author is Jin Huang, who earned his doctorate from UCLA in 2021. Other UCLA co-authors are doctoral students Zeyan Liu, Bosi Peng and Yang Liu; former graduate students Mufan Li and Sung-Joon Lee; postdoctoral researcher Chengzhang Wan; assistant project scientist Enbo Zhu, who worked on the study as a doctoral student and postdoctoral researcher at UCLA; and Xiangfeng Duan, a professor of chemistry and biochemistry. Other authors are from Brookhaven National Laboratory in New York, Italy’s National Research Council, Northeastern University and UC Irvine.

This research was supported by the US Office of Naval Research and the National Science Foundation.

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