In situ self-assembly synthesis of sandwich-like TiO2/reduced graphene oxide/LaFeO3 Z-scheme ternary heterostructure towards enhanced photocatalytic hydrogen production

In the present work, an indirect Z-schematic heterojunction system of TiO2 and LaFeO3 (LFO) with a solid state electron mediator (RGO) is proposed and applied for photocatalytic hydrogen (H-2) evolution. Through a facile 2-step synthesis strategy including adsorption of LFO on GO sheets and growth of TiO2 between the LFO-GO frameworks, a Ti-O-C bonds strongly linked sandwich-like TiO2/RGO/LFO composite is obtained. The structure, morphology, optical properties and catalytic mechanism of the Z-scheme heterojunction are thoroughly investigated. The obtained visible light responded TiO2/RGO/LFO composite displays significantly elevated photocatalytic performance for H-2 evolution with excellent stability, and its H-2 production rate (0.893 mmol h(-1) g(-1) ) is approximately 3.2, 14.4 and 11.4 times superior to the direct Z-scheme TiO2/LFO composite, pure TiO2 and LFO, respectively. The sandwich-like structure with strong interaction between three components and short diffusion distance for impactful separation of e-h(+) pairs bring about a vast improvement in Hy evolution performance of TiO2 /RGO/LFO composite. In addition, Ti-O-C bonds could also enhance electronic conductivity and structure stability as a bridge of photogenerated carriers. Based on the investigation results, possible mechanisms for synthesis and photocatalytic charge transfer pattern for TiO2/RGO/LFO are developed.