Construction of LaFeO3/g-C3N4 nanosheet-graphene heterojunction with built-in electric field for efficient visible-light photocatalytic hydrogen production

Abstract Photocatalytic hydrogen desorption from water has been considered to be a more effective way to solve energy shortages. However, the relatively high charge recombination rate and poor recyclability are the principal factors restricting the realistic utilization of photocatalysts. Herein, in order to improve the utilization of photogenerated carriers and the response range of visible light, a ternary composite material LaFeO3/g-C3N4 nanosheets-graphene had been successfully prepared. A series of systematic studies on the structure, microscopic morphology, magnetic properties and photocatalytic hydrogen evolution activity have been carried out. The combination of CNNS, LaFeO3 and graphene in the composites was confirmed by XRD and XPS. SEM and TEM results show that LaFeO3 micro-particles grow uniformly on the CNNS flaps and the graphene is observed to cover the surface of the LaFeO3/CNNS. The optical properties indicate that the absorption edge of the composite material extends to the visible light region. The excellent photocatalytic performance of LFO/CNNS-0.25G composite (1326.5 μmol h−1 g−1) is mainly result in the improved redox capacity and carrier separation due to the tight C–O–Fe bond of Z-scheme heterojunction, meanwhile, the introduction of graphene also broadens the visible light response and accelerates the carrier transport. This research can provide a novel strategy for designing artificial photocatalytic systems with high charge transfer efficiency.