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Abstract 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⁻¹using 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. 

Abstract Electrocatalytic proton reduction to form dihydrogen (H₂) is an effective way to store energy in the form of chemical bonds. In this study, we validate the applicability of a main‐group‐element‐based tin porphyrin complex as an effective molecular electrocatalyst for proton reduction. A PEGylated Sn porphyrin complex (SnPEGP) displayed high activity (−4.6 mA cm⁻²at −1.7 V vs. Fc/Fc⁺) and high selectivity (H₂Faradaic efficiency of 94 % at −1.7 V vs. Fc/Fc⁺) in acetonitrile (MeCN) with trifluoroacetic acid (TFA) as the proton source. The maximum turnover frequency (TOF_max) for H₂production was obtained as 1099 s⁻¹. Spectroelectrochemical analysis, in conjunction with quantum chemical calculations, suggest that proton reduction occurs via an electron‐chemical‐electron‐chemical (ECEC) pathway. This study reveals that the tin porphyrin catalyst serves as a novel platform for investigating molecular electrocatalytic reactions and provides new mechanistic insights into proton reduction. 

Main group elements are promising for developing electrochemical H₂production or CO₂reduction catalysts.