Hollow CaTiO3 cubes modified by La/Cr co-doping for efficient photocatalytic hydrogen production

In this work, we have applied microstructure management and doping techniques to conventional wide band gap semiconductor CaTiO 3 with the aim to improve its light absorption and photocatalytic activity. A series of La/Cr co-doping hollow CaTiO 3 cubes have been successfully prepared by a template-free hydrothermal method. Their crystal structures, microstructures, optical absorption and photocatalytic hydrogen production have been systematically investigated. Our results suggest that hollow CaTiO 3 owns a higher light absorption than solid one and demonstrates a much better photocatalytic activity both under full range (λ   ≥   250   nm) and visible light illumination (λ   ≥   400   nm). These improvements probably originate from the peculiar hollow microstructures that increase photon-matter interactions and shorten the charge migration pathways. The photocatalytic activity for hydrogen production has been further studied by varying the La/Cr content in CaTiO 3 . An optimal doping point at 5% La/Cr doping level has been reached for full range illumination with apparent quantum efficiency approaching ∼2.41%. Nevertheless, the activity under visible light illumination shows a clear dependence on doping level with highest apparent quantum efficiency ∼0.40% at 20% La/Cr doping level. DFT calculations reveal the critical role of Cr in forming a new spin-polarized valence band inside the original band gap of CaTiO 3 therefore is responsible for band gap reduction and visible light photocatalysis. This work here highlights the importance of microstructure control to the photocatalytic performance and shall shed a light on the design and development of efficient photocatalytic materials/systems.