Thermal-driven Z-scheme spinel CuAl2O4-decorated TiO2(B) heterojunction for accelerated charge transfer and enhanced hydrogen evolution.

Harnessing solar energy for hydrogen (H2) generation represents a sustainable route toward carbon-neutral energy conversion. However, its efficiency is often hindered by sluggish charge transport and severe carrier recombination. In this work, a thermally driven Z-scheme heterojunction composed of spinel Copper aluminium oxide (CuAl2O4) and monoclinic titanium dioxide (TiO2(B)) is developed to overcome these limitations. CuAl2O4, with its suitable band alignment and excellent redox stability facilitates rapid interfacial charge transfer. The well-integrated CuAl2O4/TiO2(B) interface establishes an internal electric field that drives directional charge migration, while thermal excitation further enhances carrier mobility and accelerates surface reaction kinetics. This synergistic photothermal coupling substantially amplifies the H2 evolution activity, delivering an impressive H2 production rate of 2687 µmol g-1 h-1 under natural sunlight and heat-assisted conditions, along with outstanding durability. The results demonstrate that integrating the robust spinel CuAl2O4 with TiO2(B) via a thermally assisted Z-scheme heterojunction effectively preserves strong redox potentials while minimizing recombination losses, highlighting the potential of this strategy for the rational design of thermally enhanced heterojunction photocatalysts for efficient solar-to-hydrogen conversion.