Surface Nanosteps Modulate the Local Environment of Co Single Atoms to Boost the Electrocatalytic Hydrogen Evolution Reaction

Modulating the coordination environment of non-noble-metal single-atom catalysts is of great significance to boost their catalytic performance. However, the outcome of this approach strongly relies on the structural design of the support. Herein, we demonstrate that nanosteps on titanium oxide, which can be simply generated by HCl etching, enable regulation of the coordination environment of anchored Co single atoms. Thus, experimental and theoretical results revealed that nanostepped TiO2 selectively anchors three-coordinated Co–P3 on the step-edge, while flat TiO2 supports four-coordinated Co–P3O. These Co–P3 sites demonstrate significantly enhanced hydrogen evolution reaction (HER) performance, achieving a mass activity approximately 8.3 times greater than that of the Co–P3O on flat TiO2. The unsaturated step-edge configuration of TiO2 induces more electron transfer from the support to Co–P3 through the Ti–P–Co pathway. This electron accumulation is further amplified by the electric field effect induced by nanosteps and optimizes the energy required for H2O dissociation and OH*/H* adsorption and desorption during the electrocatalytic HER.