Space-induced charge carriers separation enhances photocatalytic hydrogen evolution on hollow urchin-like TiO₂ nanomaterial

The controlled modification of the inner and outer surfaces of hollow nanostructures with dual cocatalysts possessing redox ability is a key factor for improving the charge carrier separation efficiency and surface catalytic reaction efficiency of a catalyst. Herein, a novel hollow urchin-like TiO₂ nanomaterial with Pt loaded on the inner surface and RuO₂ on the outer surface is reported. The Pt acts as the electron capture centre and is responsible for the reduction reaction, whereas the RuO₂ acts as the hole-trapping centre for the oxidation reaction. Compared to nanospheres, the urchin-like structures have a larger specific surface area. Moreover, the as-prepared TiO₂ contained numerous single-electron oxygen vacancies (Vo·). The synergy between the highly dispersed catalytic material and spatially separated dual cocatalysts, characterised by hollow structures, a large specific surface area, and oxygen vacancies, greatly increased the activity of the catalyst. When Pt (0.5 wt%) is loaded on the inner surface of the nanomaterials, the hydrogen evolution rate is as high as 2045.1 μmolg⁻¹h⁻¹; moreover, it further improves to 3904.0 μmolg⁻¹h⁻¹ when RuO₂ is loaded on the outer shell.