Sulfurization-Assisted Cobalt Deposition on Sm₂Ti₂S₂O₅ Photocatalyst for Water Oxidation under Visible Light Irradiation

Deposition of cocatalyst is an efficient way for photocatalytic water splitting to improve solar energy conversion efficiency, and its deposition method has been known to make a great effect. In this work, we introduced a sulfurization-assisted deposition method to load earth-abundant cobalt cocatalyst for the purpose of promoting water oxidation performance of Sm 2 Ti 2 S 2 O 5 oxysulfide that is characterized with wide visible light absorption. The cobalt deposition introduced here undergoes first formation of CoS x by sulfurization at high temperature and subsequent conversion into CoO x by calcinations in air. Compared to conventionally impregnated cobalt or IrO 2 colloids, the sulfurization-assisted cobalt deposition well maintains structure of photocatalyst and inhibits the formation of defect sites leading to better separation of photogenerated carriers and water oxidation performance. The apparent quantum efficiency of the optimized sample reaches 5.0% at 420 nm. The sulfurization-assisted deposition actually open a new way to modify the (oxy)sulfide semiconductors.