Visualization of oxophilic regulation for alkaline hydrogen evolution on Ni-based electrocatalyst via multimodal operando approaches.

Alkaline hydrogen evolution reaction holds immense promise for sustainable energy conversion due to its inherent compatibility with earth-abundant electrocatalysts and potential for large-scale, high-purity hydrogen production. However, sluggish kinetics remain a formidable bottleneck for its industrial deployment. Although incorporating oxophilic components is widely used to promote water activation, the catalytic role of oxygen-affinity-related sites is often interpreted statically, without considering dynamic evolution of local coordination under operating conditions. Here, we synthesize a crystalline-amorphous Ni/TiO2 heterojunction via a grain-boundary segregation strategy and combine multi-modal operando techniques to directly visualize reversible, bias-induced reconstruction of the oxophilic component. These observations provide direct evidence that, at the Ni/TiO2 interface, oxygen affinity is a tunable parameter encoded by nanoscale coordination and interfacial chemistry, and elucidate how its modulation governs water dissociation and hydroxyl handling. We demonstrate that the resulting four-coordinated Ti sites serve as highly efficient centers for water dissociation and hydroxyl adsorption, thereby synergistically optimizing the hydrogen adsorption/desorption energetics. This work offers a mechanistic and methodological basis for rational nano-heterointerfaces engineering in advanced electrocatalysts.