Mesocrystalline Ti3+[sbnd]TiO2 hybridized g-C3N4 for efficient visible-light photocatalysis

Abstract

TiO2 mesocrystals are often considered to be a fascinating and efficient photocatalyst because of its long lifetime carriers and effective conduction pathways. However, TiO2 mesocrystals showed no visible light response and visible light photocatalytic activity. To overcome these shortages, mesocrystalline Ti3+TiO2 (meso-TiO2) and its composites are highly desired to have strong capacity for harvesting visible light and photocatalytic hydrogen production. In this work, Ti3+ doped TiO2 mesocrystals were successfully prepared through oriented attachment mechanisms, and direct Z-scheme Ti3+ self-doped TiO2 mesocrystals/g-C3N4 composites were also prepared by facile solvethermal method. The as-prepared Ti3+TiO2 mesocrystals showed visible light absorption and photocatalytic activity for hydrogen production. Interestingly, the as-prepared Ti3+ doped meso-TiO2/g-C3N4 composites displayed highly improved visible light absorption and visible light photocatalytic activity for hydrogen production, and the highest photocatalytic activity for hydrogen production was about 3748.46 μmol g−1 h−1 with an apparent quantum efficiency of 1.42% at 400 nm (sacrificial agent, triethanolamine) and 983.56 μmol g−1 h−1 (sacrificial agent, methanol), much higher than that of g-C3N4 and Ti3+ doped TiO2 mesocrystals, mainly due to the high charge separation efficiency, long lifetime carriers and effective transport pathways. Finally, possible direct Z-scheme photocatalytic mechanism of Ti3+ doped meso-TiO2/g-C3N4 composites were proposed in detail.