Oxygen-Defective Bi₂MoO₆/g-C₃N₄ hollow tubulars S-scheme heterojunctions toward optimized photocatalytic performance

Novel S-scheme heterojunction photocatalysts of bismuth molybdate/hollow tube graphite carbon nitride (Bi₂MoO₆ SOVs/g-C₃N₄) containing surface defects (SOVs) were prepared by calcination and hydrothermal methods. The hollow tubular structure of g-C₃N₄ facilitates the enhancement of multiple reflection and scattering of light, and also have a larger range of specific surface areas and more reactive sites, which promotes carrier separation and thus improves photocatalytic performance. The introduction of SOVs to bismuth molybdate not only reduces the band gap of bismuth molybdate, but also promotes the separation of charges. The optimized Bi₂MoO₆ SOVs/TCN photocatalyst has a hydrogen production efficiency of 2.29 mmol h^-1 g^-1. It also shows high photocatalytic degradation property of tetracycline and bisphenol A in water, up to 97.3 % and 98.9 %, respectively. Meanwhile, the transfer mechanism of photogenerated charges in S-scheme heterojunctions can be verified by electron paramagnetic resonance and in situ irradiated x-ray photoelectron spectroscopy electron paramagnetic resonance, which accelerated the separation and transfer of photogenerated charge by energy band bending at the interface and internal electric field. This rational structural design strategy provides a new development idea for building high-performance S-scheme heterojunction photocatalysts.