Nitrogen-rich carbon nitride (C₃N₅) coupled with oxygen vacancy TiO₂ arrays for efficient photocatalytic H₂O₂...

Developing efficient and facilitated recycling photocatalysts for H₂O₂ formation is an ideal strategy for solar-to-chemical energy conversion. In this work, we synthesized ultrathin C₃N₅ nanosheets through the process of thermal polymerization and polyvinylpyrrolidone (PVP)-assisted solvent exfoliation. Subsequently, the obtained ultrathin C₃N₅ nanosheets were tightly attached to the surface of TiO_2-x arrays, resulting in an enhanced photocatalytic H₂O₂ production rate. The density functional theory (DFT) calculations demonstrate that an internal electric field (IEF) is generated between the TiO_2-x array and the ultrathin C₃N₅ due to the different work functions. The presence of IEF provides an additional driving force for carrier separation and transfer in the heterointerface. Benefitting from this unique strategy, the optimal heterojunction obtains the highest H₂O₂ formation rate (2.93 μmol/L/min), which is about 4.1 times than that of TiO_2-x arrays. The rotating disk electrode (RDE) analysis manifests H₂O₂ formation through 2e^--dominated oxygen reduction reaction (ORR). This research provides an innovative strategy for assembling a type-II heterojunction with a useful IEF for efficient photocatalytic H₂O₂ production.