A Simple Fabrication of Sb₂S₃/TiO₂ Photo-Anode with Long Wavelength Visible Light Absorption for Efficient Photoelectrochemical Water Oxidation

An Sb2S3-sensitized TiO2 (Sb2S3/TiO2) photo-anode (PA) exhibiting a high photo-electrochemical (PEC) performance in water oxidation has been successfully prepared by a simple chemical bath deposition (CBD) technique. Herein, the Raman spectra and XPS spectrum of Sb2S3/TiO2 confirmed the formation of Sb2S3 on the TiO2 coatings. The Sb2S3/TiO2 photo-anode significantly shifted the absorption edge from 395 nm (3.10 eV) to 650 nm (1.90 eV). Furthermore, the Sb2S3/TiO2 photo-anode generated a photo-anodic current under visible light irradiation below 650 nm due to the photo-electrochemical action compared with the TiO2 photo-anode at 390 nm. The incident photon-to-current conversion efficiency (IPCE = 7.7%) at 400 nm and −0.3 V vs. Ag/AgCl was 37 times higher than that (0.21%) of the TiO2 photo-anodes due to the low recombination rate and acceleration of the carriers of Sb2S3/TiO2. Moreover, the photo-anodic current and photostability of the Sb2S3/TiO2 photo-anodes improved via adding the Co2+ ions to the electrolyte solution during photo-electrocatalysis.