Band structure engineering of PTI in C-PTI/ZnO heterostructures for enhanced visible-light-driven H₂ evolution

Polytriazine imide (PTI), a triazine-based carbon nitride has a wider band gap and more positive conduction band (CB) potential compared to those of graphitic carbon nitride (g-C₃N₄). Therefore, it is highly desired to develop an effective strategy to optimize the band structure of PTI for the enhancement of the photocatalytic performance, especially upshift the conductive band potential. Here, a ternary C-PTI/ZnO (CPZ) photocatalyst was developed via a simple one-step molten salt method. In the obtained CPZ sample, the carbon ring in-plane connects to the triazine ring, leading to the formation of C-PTI nanosheets. The carbon ring incorporation not only efficiently narrows the band gap of PTI, but also shifts its conduction band potential negatively and accelerates the photogenerated electron transport. In addition, ZnO nanoparticles are well dispersed on the C-PTI nanosheets, further promoting the charge carriers transfer and separation. As a result, the CPZ sample presents a photocatalytic H₂ evolution rate up to 52 μmol h^-1 under visible light, which is 60 and 179 times higher than that of C-PTI and PTI, respectively.