Grain Boundary Tailors the Local Chemical Environment on Iridium Surface for Alkaline Electrocatalytic Hydrogen Evolution

Even though grain boundaries (GBs) have been previously employed to increase the number of active catalytic sites or tune the binding energies of reaction intermediates for promoting electrocatalytic reactions, the effect of GBs on the tailoring of the local chemical environment on the catalyst surface has not been clarified thus far. In this study, a GBs-enriched iridium (GB-Ir) was synthesized and examined for the alkaline hydrogen evolution reaction (HER). Operando Raman spectroscopy and density functional theory (DFT) calculations revealed that a local acid-like environment with H