Independent Control Over the H/OH Adsorption: Breaking the Trade-Off Between H/OH-Adsorption and HO-Dissociation of Platinum-Group Metal Electrocatalyst for Hydrogen Evolution Reaction.

Platinum-group metals catalysts (such as Rh, Pd, Ir, Pt) have been the most efficient hydrogen evolution reaction (HER) electrocatalysts due to their moderate H adsorption strength, while the high HO-dissociation barrier in alkaline media restrains the catalytic performance of PGM catalysts. However, the optimization of the HO-dissociation barrier and *H/*OH binding energy toward their individual optima is limited due to the constraints of their scaling relationship on a single active site. Here, a coordinatively unsaturated "M─O─W" (M = Rh, Pd, Ir, Pt) active area is constructed, where H and OH species are anchored on Pt-group metal sites and inactive W sites for individual regulation. By combining experiments and density functional theory calculations, the introduction of extra OH-adsorption sites (coordinatively unsaturated WO) avoids the competitive adsorption of H and OH on the single site, while the enhanced OH-adsorption capacity on the coordinatively unsaturated WO effectively facilitates the adsorption/dissociation of interfacial HO. As a result, the representative Rh-WO catalyst exhibits outstanding catalytic activity and durability for HER. The findings of this work not only provide valuable insights for the design of efficient PGM catalysts for HER but also shed light on the development of electrocatalysts for other catalytic reactions.