Electrocatalytic hydrogen evolution with gallium hydride and ligand-centered reduction

摘要

Ga^III chloride tetrakis(pentafluorophenyl)porphyrin (>1) was synthesized and shown to be a highly active and stable post-transition metal-based electrocatalyst for the hydrogen evolution reaction (HER). Electrochemical and spectroscopic studies indicate that both the first and second reduction events of >1 are ligand-centered. The 2e-reduced form >1^2– reacts with a proton to give Ga^III–H species (>1–H), which undergoes protonolysis with Brønsted acids to produce H2. The identification of key intermediates >1^–, >1^2–, and >1–H leads to a catalytic cycle, which is valuable for the fundamental understanding of the HER. This study presents a rare but highly active HER electrocatalyst with unusual features, including ligand-centered electron transfer and formation of post-transition metal hydride.