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

Developing efficient and facilitated recycling photocatalysts for H 2 O 2 formation is an ideal strategy for solar-to-chemical energy conversion. In this work, we synthesized ultrathin C 3 N 5 nanosheets through the process of thermal polymerization and polyvinylpyrrolidone (PVP)-assisted solvent exfoliation. Subsequently, the obtained ultrathin C 3 N 5 nanosheets were tightly attached to the surface of TiO 2-x arrays, resulting in an enhanced photocatalytic H 2 O 2 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 C 3 N 5 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 H 2 O 2 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 H 2 O 2 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 H 2 O 2 production.