MoO_x embedded S-g-C₃N₄ frameworks with enhanced photocatalytic H₂ generation and phenol removal

Combining defect introduction and heterojunction construction, MoO_x/S-g-C₃N₄ S-scheme heterojunctions were created through the in-situ growth of defective MoO_x during the secondary thermal polymerization of bulk S-doped g-C₃N₄. Mechano-chemical pretreatment resulted in the homogeneous distribution of S components and molybdate precursors in g-C₃N₄ frameworks. The secondary thermal polymerization of bulk S-doped g-C₃N₄ at high temperature (700 °C) created layered MoO_x with homogeneous distribution and formed heterojunctions with well-developed interface to improve charge carrier transfer. The effect of thermal polymerization temperature and S-g-C₃N₄ situation on the performance was tested. The reducibility of g-C₃N₄ skeleton during thermal polymerization resulted in the formation of high-concentration oxygen vacancies within MoO₃ lattice, in which, oxygen vacancies significantly expanding light response to a near-infrared region to increase the harvesting ability of solar energy and effectively modulate the charge transfer pathway. The heterojunction sample revealed enhanced photocatalytic H₂ generation rate (3874 μmolg^-1h^-1) and removal efficiency of 2,4-dichlorophenol, (a degradation kinetic k of 0.018) which were enhanced by 7 and 6 times, respectively, compared with S-doped g-C₃N₄ nanosheets. The formation of S-scheme heterojunction and photocatalytic mechanism were investigated. These results supply an efficient example for defect engineering in photocatalyst fabrication and green energy conversion.