Promoting hydrogen evolution reaction with a sulfonic proton relay

Enzymes can activate otherwise unreactive substrates by using residues precisely located in the active sites. We herein report on a Ga porphyrin which bears second-sphere sulfonic group (named as 1) and its high efficiency for electrocatalytic hydrogen evolution reaction (HER). Complex 1 achieve large TOF value of 1.3 × 105 s−1 at low 295-mV overpotential with weak acetic acid (HOAc) proton source. Notably, catalyze H2 generation potentials close to thermodynamic HER equilibrium, but sulfonic-free analogues require >250 mV more cathodic initiate HER. Mechanistic studies showed that two-electron reduced porphyrins were protonated form GaIII-H. For 1, GaIII-H underwent rapid protonolysis HOAc evolve H2, analogues, their required further reduction trigger catalysis. This work presents synthetic molecular catalyst rates under overpotentials promoting metal hydrides acids.