Water electrolysis is a key technology for producing green hydrogen energy, but its efficiency is limited by the sluggish oxygen evolution reaction (OER) kinetics at the anode. Studies have shown that the intrinsic reaction barrier stems from the spin-state transition from singlet H₂O/OH⁻ to triplet O₂. However, effective strategies to regulate the spin states of OER catalysts remain scarce. While external magnetic field enhancement has been explored, it requires additional energy input and its mechanism remains controversial. Therefore, developing new spin-regulation strategies under field-free conditions is urgently needed.
Recently, researchers at Xi’an Jiaotong University (XJTU) have proposed a novel mechanism for atomic-level localized spin regulation via an asymmetric Fe-Ni tacticity strategy. By introducing Fe into the NiPS₃ lattice, a redistribution of spin states occurs, generating active Fe³⁺ sites with a medium spin (MS) state. P/S coordination further stabilizes this MS state, and the catalyst can self-sacrifice to suppress competitive Cl⁻ oxidation and Cl⁻ poisoning. The resulting catalyst demonstrates outstanding performance in both alkaline and real seawater electrolysis, requiring only 1.50 V/1.52 V at 10 mA cm⁻² and maintaining stable operation for 1000 hours. It also exhibits low-voltage operation advantages in anion exchange membrane (AEM) seawater electrolyzers (AEM(S)WE).
Using a combination of theoretical calculations, X-ray absorption spectroscopy, electron paramagnetic resonance, and Mössbauer spectroscopy, the researchers systematically revealed the critical role of MS Fe³⁺ in promoting spin-selective electron transfer. This study presents a new paradigm for intrinsic spin regulation in non-precious metal catalytic systems, offering valuable insights for the design of efficient and sustainable hydrogen evolution catalysts.
The study, titled "Asymmetric tacticity navigates the localized metal spin state for sustainable alkaline/sea water oxidation", was published in Science Advances. The State Key Laboratory for Mechanical Behavior of Materials (SKL-MBM) at XJTU is the first and sole corresponding institution. Prof. Zhengfei Dai from the Surface Engineering Research Group, School of Materials Science and Engineering (MSE), is the sole corresponding author, and Ph.D. student Yaoda Liu is the first author. The research was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Shaanxi Province, and the Analytical & Testing Center and Supercomputing Center of Xi’an Jiaotong University.
Paper link: https://www.science.org/doi/full/10.1126/sciadv.ads0861
