Tailoring a local acid-like microenvironment for efficient neutral hydrogen evolution.

Electrochemical hydrogen evolution reaction in neutral media is listed as the most difficult challenges of energy catalysis due to the sluggish kinetics. Herein, the Ir-H x WO 3 catalyst is readily synthesized and exhibits enhanced performance for neutral hydrogen evolution reaction. H x WO 3 support is functioned as proton sponge to create a local acid-like microenvironment around Ir metal sites by spontaneous injection of protons to WO 3 , as evidenced by spectroscopy and electrochemical analysis. Rationalize revitalized lattice-hydrogen species located in the interface are coupled with H ad atoms on metallic Ir surfaces via thermodynamically favorable Volmer-Tafel steps, and thereby a fast kinetics. Elaborated Ir-H x WO 3 demonstrates acid-like activity with a low overpotential of 20 mV at 10 mA cm -2 and low Tafel slope of 28 mV dec -1 , which are even comparable to those in acidic environment. The concept exemplified in this work offer the possibilities for tailoring local reaction microenvironment to regulate catalytic activity and pathway.