Thermal conversion of metal hydroxide acrylate nanoparticles immobilized on TiO₂ toward noble-metal-free photocatalytic H₂ production

Developing efficient and noble-metal-free photocatalysts for hydrogen evolution is a central challenge in solar fuel production. Herein, we report a strategy to enhance the photocatalytic activity of rutile TiO₂ by immobilising nickel hydroxide acrylate (NHA) nanoparticles, which serve as thermally convert cocatalyst precursors. Upon heat-treatment under an Ar atmosphere, the NHA nanoparticles decompose to form a composite nanostructure comprising sub-10 nm Ni/NiO_<i>x</i> and carbon nanodomains. The optimised hybrid system exhibited a 37-fold increase in photocatalytic H₂ evolution activity compared to pristine TiO₂ under UV light irradiation. Analysis of band edge potentials revealed a downward shift in the conduction band minimum, facilitating more efficient reduction processes. In contrast, a control sample prepared using Ni(NO₃)₂ resulted in inactive NiO_<i>x</i> domains and poor interfacial bonding, leading to suppressed activity. These findings demonstrate that NHA-derived cocatalysts provide a versatile platform for constructing noble-metal-free photocatalytic systems through controlled interfacial nanostructuring, offering new avenues for designing advanced solar-to-fuel materials.