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In order to meet our goals for carbon neutralization by the 2050s, we need environmentally friendly fuels. Catalysts (and their precursor, precatalysts) are key components in the electrochemical water-splitting reaction that produces clean hydrogen fuel.

Researchers at Tohoku University produced a highly stable catalyst that could feasibly be used in practical, real-world applications. To develop their catalyst, they looked at a complicated chemical and electrochemical process called "reconstruction." The findings are in the journal Nature Communications.

During catalysis, a precatalyst undergoes a reconstruction that changes its features, and either improves or impairs its catalytic activity. Reconstruction can be affected by multiple factors, including the properties of the precatalyst and electrolyte, the electrochemical induction method, or reaction temperature—making it difficult to identify the precise reconstruction mechanisms.

"It's hard to design a catalyst that works well when that catalyst itself can change. It's almost like trying to play tennis with a ball that morphs each time you hit it," says Heng Liu (Tohoku University), "Therefore, there are a lot of challenges to developing a rational and commonly applicable methodology for synthesizing high-performance catalysts."

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A Co₂Mo₃O₈ precatalyst underwent potential-dependent reconstruction, and created an electrochemically stable Co(OH)₂@Co₂Mo₃O₈ catalyst. The research team revealed that the surface structure transformation of precatalysts can be controlled by applied potentials, which is also accompanied by the etching of inherent species from the precatalyst into electrolytes.

The reconstruction of catalysts and altered electrolytes changes the entire catalysis system in such a way that performance is enhanced. The catalyst achieved a Faradaic efficiency of 99.9% versus a reversible hydrogen electrode (RHE) for hydrogen generation. Additionally, the catalyst was able to remain stable for over one month.

"In summary, the resulting catalyst was highly efficient, and able to stay in storage for extended periods of time. Our study highlights its suitability for industrial applications," says Liu.

This study advances the understanding of how precatalyst reconstruction and electrolyte evolution affect catalytic performance, which paves the way for better rational catalyst design. As catalyst design improves, it may help boost the production of clean energy sources—helping us take action against pollution and climate change.