Electrocatalytic Hydrogen Evolution Using A Molecular Antimony Complex under Aqueous Conditions: An Experimental and Computational Study on Main‐Group Element Catalysis

Electrocatalytic hydrogen gas production is considered a potential pathway towards carbon‐neutral energy sources. However, the development of this technology is hindered by the lack of efficient, cost‐effective, and environmentally benign catalysts. In this study, a main‐group‐element‐based electrocatalyst, SbSalen, is reported to catalyze the hydrogen evolution reaction (HER) in an aqueous medium. The heterogenized molecular system achieved a Faradaic efficiency of 100 % at −1.4 V vs. NHE with a maximum current density of −30.7 mA/cm2. X‐ray photoelectron spectroscopy of the catalyst‐bound working electrode before and after electrolysis confirmed the molecular stability during catalysis. The turnover frequency was calculated as 43.4 s−1 using redox‐peak integration. The kinetic and mechanistic aspects of the electrocatalytic reaction were further examined by computational methods. This study provides mechanistic insights into main‐group‐element electrocatalysts for heterogeneous small‐molecule conversion. An antimony complex was synthesized and heterogenized onto a carbon paper electrode surface. This system is capable of electrocatalytically evolving hydrogen gas under aqueous acidic conditions with high activity and efficiency. The stability of the heterogenized complex was confirmed by XPS of the used electrode surface and ICP‐MS of the post catalysis electrolyte. Computational kinetic studies suggest that the generation of hydrogen‐catalyst adduct is a rate‐limiting step.