Synthesis of metal-free Si/SiC composite for photocatalytic hydrogen production

Silicon carbide (SiC) has been investigated as a promising semiconductor photocatalyst for water splitting because of its excellent photocatalytic activity and high chemical/thermal stability. However, the fast combination of photogenerated carriers restricts the photocatalytic efficiency of SiC. In this study, we investigated the Si/SiC composite synthesized through a simple carbothermal reduction method at 1250 degrees C by using biomass-activated carbon and silicon monoxide as carbon and silicon sources, respectively. The photocatalytic hydrogen (H-2) evolution (PHE) performance of the Si/SiC composite was investigated under simulated solar light irradiation in pure (deionized) water without any sacrificial agent. Experimental results show that the composite exhibited an excellent photocatalytic activity toward H 2 production with a value of 14.01 mu mol.h(-1).g(-1), which was approximately 18 times higher than that of pure SiC. The experimental analysis reveals that the PHE mechanism over Si/SiC is different from that of the general type I heterogeneous photocatalyst. The synergistic effect of the Si-SiC heterojunction based on the work function difference accelerated the separation of the photogenerated electrons and holes, thereby enhancing the photocatalytic activity of the composite. Si served as the electron collector. The Si/SiC composite, which has low cost, scalability, and eco-friendly characteristics, is a suitable solar-H-2 production photocatalyst in practical applications. [GRAPHICS] .