Network-like CuInS₂ photocathode and modified with noble metal co-catalyst for photoelectrochemical water splitting

It is of great significance to explore new preparation methods and control the morphology and proportion of metal ions for the photoelectrochemical (PEC) water splitting of ternary sulfide photoelectrode. In this paper, the network-like CuInS₂ film photocathodes were firstly prepared by hydrothermal growth method. The effects of different [Cu²⁺]/[In³⁺] molar ratios and concentrations of growth solution on CuInS₂ films were investigated in detail. The mechanism of the synthetic reaction was studied. The best PEC photocurrent density of the CuInS₂ film photoelectrode is − 0.81 mA/cm² at − 0.6 V versus RHE when the [Cu²⁺]/[In³⁺] molar ratio is 0.4, the growth solution concentration is 8 mmol/L CuCl₂·2H₂O, 20 mmol/L InCl₃·4H₂O and 60 mmol/L C₂H₅NS. For the purpose of further improving photoelectrochemical properties of CuInS₂ thin films, the Pt co-catalyst was loaded. The synthesized CuInS₂–Pt thin film yielded a photocurrent density for − 1.92 mA/cm² at − 0.6 V versus RHE due to the fast photogenerated electrons capture ability of Pt co-catalyst. The method of constructing photoelectrode film and the co-catalyst mechanism contributes to a sensational way for PEC water splitting of sulfide.