Electrocatalytic water splitting, a process that entails breaking down water into hydrogen and oxygen, is a promising approach to produce clean hydrogen for fuel cells, which could in turn be used to power large electric vehicles. So far, the real-world use of this process has been limited by the sluggish kinetics of the oxygen evolution reaction (OER), a key chemical reaction occurring at the anode.
Researchers at Max-Planck-Institute for Chemical Physics of Solids, Weizmann Institute of Science and other institutes recently introduced an innovative approach to accelerate this reaction, using topological chiral semimetals as electrocatalysts.
Their findings, published in Nature Energy, demonstrate that spin-orbit coupling (SOC) inherent in these materials can be leveraged to boost OER activity, facilitating more efficient electrocatalytic water splitting.
“Our research was driven by the pressing need for clean and sustainable energy solutions,” Xia Wang, first author of the paper, told Tech Xplore.
“Specifically, we aimed to address the challenge of improving electrocatalytic water splitting for hydrogen production, with a focus on the OER, a critical step often hindered by sluggish kinetics. The inspiration came from the distinctive electron transport properties of topological chiral semimetals, which offered a promising pathway to address the limitations of traditional catalysts.”
The key goal of the recent study by Wang and her colleagues was to harness the quantum properties of topological chiral semimetals to enhance OER efficiency. To achieve this, the team first synthesized a series of Rh-based topological chiral semimetals with varying SOC strengths, including RhSi, RhSn and RhBiS.
“These materials feature both highly ordered geometrical chirality and electronic chirality, which enable the generation of spin-polarized carriers critical for enhancing catalytic activity,” explained Wang.
“By benchmarking their performance against achiral reference materials, we demonstrated that the chiral crystals significantly outperform state-of-the-art catalysts, such as RuO2, achieving up to two orders of magnitude higher specific activity in alkaline electrolytes.”
The results gathered by Wang and her colleagues reveal a direct link between the strength of SOC in topological chiral semimetals, the polarization of spins, and the materials’ catalytic activity. This important finding could guide the future design of electrocatalysts for water splitting, leading to the identification of topological materials that result in optimal OER activity.
“The most notable achievement of our study is the experimental validation of a direct link between SOC and OER performance, establishing a robust design principle for spin-dependent catalysts,” said Wang. “Among the materials we studied, RhBiS emerged as a standout performer, demonstrating remarkable OER activity, with specific activity far exceeding that of conventional catalysts.”
The recent work by this team of researchers could ultimately help to accelerate the development of advanced water-splitting technologies. This could in turn facilitate the adoption of green hydrogen-based energy solutions, including fuel cells to power electric planes, trucks and other large vehicles.
“This work lays a foundation for employing spin-orbit coupling as a tool to design more effective topological catalysts,” said Prof. Maggie Lingerfelder at EPFL, who is an expert in the field.
“In my view, spin orbit coupling has been an underexplored aspect in the design of selective catalysts, but it could potentially explain even why Pt exhibits such versatile catalytic behavior across various reactions. This work opens up exciting avenues for future exploration, as it brings the solid state physics community closer to applications of chiral topological materials in spin-controlled chemistry.”
In their next studies, Wang and her colleagues plan to build on their findings, expanding their investigations to other topological materials with different electronic and magnetic properties. This could allow them to further optimize spin-polarized carrier generation.
“We also plan to focus on real-world applications by developing scalable, cost-effective catalysts and evaluating their performance in industrially relevant settings,” added Wang.
“By bridging the gap between fundamental research and practical implementation, we hope to contribute meaningfully to the advancement of sustainable energy technologies.”
