Organometallic Ni Pincer Complexes for the Electrocatalytic Production of Hydrogen

Nonplatinum metals are needed to perform cost-effective water reduction electrocatalysis to enable technological implementation of a proposed hydrogen economy. We describe electrocatalytic proton reduction and H₂ production by two organometallic nickel complexes with tridentate pincer ligands. The kinetics of H₂ production from voltammetry is consistent with an overall third order rate law: the reaction is second order in acid and first order in catalyst. Hydrogen production with 90–95% Faradaic yields was confirmed by gas analysis, and UV–vis spectroscopy suggests that the ligand remains bound to the catalyst over the course of the reaction. A computational study provides mechanistic insights into the proposed catalytic cycle. Furthermore, two proposed intermediates in the proton reduction cycle were isolated in a representative system and show a catalytic response akin to the parent compound