Enhanced photocatalytic CO2 reduction over direct Z-scheme NiTiO3/g-C3N4 nanocomposite promoted by efficient interfacial charge transfer

Abstract Photocatalytic CO2 reduction to fuels is recognized as a favorable solution to solve the energy crisis and greenhouse effect simultaneously. Herein, to improve the photoreduction efficiency of CO2, a direct Z-scheme NiTiO3/g-C3N4 (NT/GCN) photocatalyst is constructed by a facile calcination method. The highest yield of CH3OH (13.74 μmol∙g-1∙h-1) can be obtained at the optimized NT/GCN40 without any sacrificial agent and cocatalyst, almost 3.29 times higher compared with g-C3N4. Simultaneously, mechanism study by the band potential estimation and electron spin resonance (ESR) analysis provide evidences that the enhanced photoactivity is ascribed to the Z-scheme. This unique structure can enhance the spatial separation of hole-electron pairs, suppress the recombination of charge carriers and remain the strong redox ability. Moreover, this direct Z-scheme NT/GCN40 composite shows good reusability. This work may present a novel way for the design and manufacture of Z-scheme photocatalysts for energy conversion and environmental remediation.