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. Alkaline hydrogen production is hindered by sluggish kinetics and limited insight into how oxophilic sites evolve. Here, the authors uncover reversible reconstruction at nickel titania interfaces that creates four coordinated titanium sites for efficient water dissociation and hydroxyl adsorption.