Electronic Structure‐Dependent Water‐Dissociation Pathways of Ruthenium‐Based Catalysts in Alkaline H2‐Evolution

Abstract Ruthenium (Ru)‐based catalysts have displayed compelling hydrogen evolution activities, which hold the promising potential to substitute platinum in alkaline H 2 ‐evolution. In the challenging alkaline electrolytes, the water‐dissociation process involves multistep reactions, while the profound origin and intrinsic factors of diverse Ru species on water‐dissociation pathways and reaction principles remain ambiguous. Here the fundamental origin of water‐dissociation pathways of Ru‐based catalysts in alkaline media to be from their unique electronic structures in complex coordination environments are disclosed. These theoretical results validate that the modulated electronic structures with delocalization‐localization coexistence at their boundaries between the Ru nanocluster and single‐atom site have a profound influence on water‐dissociation pathways, which push H 2 O* migration and binding orientation during the splitting process, thus enhancing the dissociation kinetics. By creating Ru catalysts with well‐defined nanocluster, single‐atom site, and also complex site, the electrocatalytic data shows that both the nanocluster and single‐atom play essential roles in water‐dissociation, while the complex site possesses synergistically enhanced roles in alkaline electrolytes. This study discloses a new electronic structure‐dependent water‐dissociation pathway and reaction principle in Ru‐based catalysts, thus offering new inspiration to design efficient and durable catalysts for the practical production of H 2 in alkaline electrolytes.