Carbon hollow spheres as cocatalyst of Cu-doped TiO₂ nanoparticles for improved photocatalytic H₂ generation

The reasonable employment of cocatalyst in photocatalysis can effectively promote the photocatalytic H₂ production activity. In this study, carbon hollow spheres (C), as a good conductive nonmetallic material, have been utilized as a novel cocatalyst and a matrix for loading the Cu-doped-TiO₂ nanoparticles by a successive hydrothermal method and metal molten salt method. The Cu-doped-TiO₂ nanoparticles were tightly anchored on the surface of carbon hollow sphere to form a zero-dimensional/three dimensional (0D/3D) Cu-doped-TiO₂/C heterojunction. The optimal Cu-doped-TiO₂/C heterojunction demonstrated greatly enhanced photocatalytic H₂ generation activity (14.4 mmol·g⁻¹·h⁻¹) compared with TiO₂ (0.33 mmol·g⁻¹·h⁻¹) and TiO₂/C (0.7 mmol·g⁻¹·h⁻¹). The performance improvement was mainly due to the synergistic effect of carbon hollow sphere cocatalyst and Cu-doping, the Cu-doping in TiO₂ nanoparticles can minimize charge recombination and enhance the available photoexcited electrons, while the 3D carbon hollow spheres can act as electron traps to accelerate the charge separation and offer abundant active sites for solar water splitting reaction.