p-Block element in platinum group metal: Mechanism insight and structure design for alkaline hydrogen electrocatalysis

Hydrogen, as a promising alternative to traditional fossil fuels, is crucial for addressing global energy shortage and environmental pollution. Remarkably, the hydrogen can be efficiently conversed and utilized by hydrogen electrocatalysis, consisting of hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR). Nevertheless, even for the platinum group metal (PGM) catalysts, there exists the orders-of-magnitude kinetic gap between the HER/HOR in acidic and alkaline electrolytes, which severely restricts the advance of alkaline hydrogen energy technologies. Consequently, developing cost-effective and efficient alkaline HER/HOR electrocatalysts is of great significance. Remarkably, the introduction of p-block elements into PGM can induce the p-d orbital hybridization, electron structure regulation, intermediate behavior optimization, and so on, thus greatly enhancing the catalytic performance. Herein, the recent progress in alkaline HER/HOR on PGM-based electrocatalysts modified by p-block elements is summarized. Firstly, the detailed discussions on alkaline HER/HOR mechanism are conducted. Then, the design strategies for p-block non-metal and metal element modified PGM-based catalysts are summarized, respectively. Notably, the inherent correlation between the distinct catalytic component (p-block elements and PGM elements) and corresponding catalytic performance is emphatically explored. Finally, in view of the challenges in alkaline HER/HOR, the research directions in the future are proposed.