Enhancing dual functional oxygen-vacant Z-scheme 3D-ZnO/2D-oxygen doped g-C3N4 nanocomposites for efficient photocatalytic bisphenol A degradation and CO2 reduction

This study presents a novel ZnO/Oxygen-doped g-C 3 N 4 (ZnO/OCN) nanocomposite photocatalyst for enhanced bisphenol A (BPA) degradation and CO 2 reduction. Synthesized via a facile air calcination-assisted hydrothermal method, the ZnO/OCN heterojunction exhibits significantly improved photocatalytic activity compared to individual ZnO and OCN under visible light irradiation. A remarkable 92.52% BPA degradation was achieved within 180 min using the ZnO/OCN (5%) composites. Additionally, the optimal composite yields CO and CH 4 production of 59.76 and 4.94 μmol⋅g −1 ⋅h −1 , respectively, approximately 6.64 and 2.5 times than those individual catalysts. This enhanced performance stems from the construction of a Z-scheme heterojunction, which facilitates efficient charge separation and transfer and minimizes electron-hole recombination, thereby boosting the overall photocatalytic performance. A Z-scheme mechanism mediated by oxygen vacancy was suggested for charge separation in the heterojunction. This mechanism involves the recombination of photoinduced electrons, trapped at the oxygen defect levels of ZnO, with holes in the valence band of OCN at the heterojunction interface. A comprehensive investigation, integrating radical trapping experiments and electron paramagnetic resonance (EPR) spectroscopy, confirms the critical role of lattice oxygen in the generation of O 2 − and OH. This highly efficient and sustainable photocatalytic system offers a promising solution for the simultaneous remediation of pollutants and mitigation of greenhouse gases.