Defect State Assisted Z-scheme Charge Recombination in Bi₂O₂CO₃/Graphene Quantum Dot Composites For Photocatalytic Oxidation of NO

In this work, we explored the photoinduced charge carriers dynamics rationalizing the photocatalytic oxidation of NO over N-doped Bi2O2CO3/graphene quantum dots composites(N-BOC/GQDs) via time-resolved photoluminescence (TRPL). Under visible light illumination, only GQDs can be photoexcited and inject electrons to N-BOC within 0.5 ns. Under UV light irradiation, the interfacial Z-scheme heterojunction recombination between the electrons in N-BOC and holes in GQDs dominate the depopulation of excited states within 0.36 ns. Such efficient Z-scheme recombination regardless of the large energy difference (1.66 eV) is mediated by the interfacial oxygen vacany defect states characterized by both density functional theory calculations (DFT) and electron paramagnetic resonance (EPR) measurement. This finding provide a novel strategic view to improve the photocatalytic performance of the nanocomposite by interfacial engineering