Scalable production of visible light photocatalysts with extended nanojunctions of WO₃/g-C₃N₄ using zeta potential and phase control in sol-gel process

Semiconductor photocatalysis for water splitting is promising approach to the current energy and environmental crisis. Although heterostructure photocatalysts exhibit enhanced photoactivity, the construction of a continuous junction at the interfaces between heterogeneous substances. In this study, visible light responsive tungsten oxide/graphitic carbon nitride composite photocatalysts with extended nanojunctions (en-WO₃/g-C₃N₄) were synthesized through a novel sol-gel process that controlled zeta potential and sol-gel phase. The rational design of porous sphere en-WO₃/g-C₃N₄ composite photocatalyst was constructed micropores and intimate contact between WO₃ nanoparticles (NPs) and 2-dimensional (2D) g-C₃N₄ platelet interface. The en-WO₃/g-C₃N₄ composite photocatalyst exhibited improved UV–vis absorbance and reduced recombination rate of photogenerated electron-hole pairs. The photocatalytic activity of hydrogen production was significantly enhanced by facile mass transfer and efficient charge-carrier separation due to direct Z-scheme mechanism. As a result, the hydrogen (H₂) production of optimal en-WO₃/g-C₃N₄ photocatalyst was obtained as much as 1060 µmol h^-1g^-1 which is 3.8-folds higher than g-C₃N₄ photocatalyst (281 µmol h^-1g^-1). Also, the designed en-WO₃/g-C₃N₄ showed good stability for H₂ production for 12 h under visible light irradiation.