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 TiO 2 and LaFeO 3 (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 TiO 2 between the LFO-GO frameworks, a Ti-O-C bonds strongly linked sandwich-like TiO 2 /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 TiO 2 /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 TiO 2 /LFO composite, pure TiO 2 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 H 2 evolution performance of TiO 2 /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 TiO 2 /RGO/LFO are developed.