A solution processed Sb2S3-based photocathode with enhanced photocatalytic performance via constructing an ultrathin TiO2 overlayer and noble metal modification

Abstract

Antimony sulfide (Sb₂S₃) is a light absorbing material with a strong visible light response, which is suitable for efficient and low-cost photoelectrodes. Nano-structured films have unique advantages for constructing photoelectrodes due to enhanced light absorption and carrier migration. However, on account of the low carrier concentration and carrier diffusion length (30–300 nm) of Sb₂S₃, finding an effective and low-cost method to grow a uniformly-coated ultrathin overlayer on a three-dimensional Sb₂S₃ film is the key to improve carrier utilization, and is significant to construct a low-cost photocathode with high efficiency. In this work, we report an Sb₂S₃-based heterostructure photocathode using nanostructured Sb₂S₃ as a light absorption layer. After coated with the ultrathin TiO₂ layer by a simple electrodeposition method and modified with Pt particles, the Sb₂S₃-based photocathode achieves a photocurrent density of 2.7 mA cm⁻² at 0 V vs. RHE in a near-neutral electrolyte, about twelve times higher than that of pure Sb₂S₃, with an onset potential of +0.55 V vs. RHE. The maximum IPCE of the Sb₂S₃-based photocathode reaches 17.5% at 700 nm. Our experimental results confirmed the promising application of Sb₂S₃ as a light absorbing material for photocatalysis, and put forward a facile and effective strategy to coat ultrathin TiO₂ on 3D nanostructured films, which will promote further investigation of nano Sb₂S₃-based photocathodes.