Controlling the Crystallographic Orientation of Sb2Se3 Film for Efficient Photoelectrochemical Water Splitting

Finding a cost‐effective semiconductor with commercial performance for photoelectrochemical (PEC) water splitting remains challenging. Sb2Se3, as a low‐cost semiconductor, has excellent photo/electric properties for PEC water splitting. Via adjusting the Sb/Se ratio in the precursor ink, the Sb2Se3 with favorable crystallographic orientation can be effectively controlled. The ink with an atomic ratio of Sb/Se = 1:3 induces the growth of a compact Sb2Se3 film with a preferred orientation, resulting in rapid charge transport and high photocurrent. After depositing TiO2 and Pt in turn, the photocathode with a structure of FTO/Au/Sb2Se3/TiO2/Pt exhibits a photocurrent density of 11.3 mA cm−2 at 0 VRHE. An unassisted solar water splitting device integrating the Sb2Se3‐based photocathode with an inorganic perovskite photovoltaic cell achieves a solar‐to‐hydrogen efficiency of 2.45%. The efficient Sb2Se3‐based photocathode shows promising potential for solar fuel production. Antimony selenide exhibits excellent optical and electrical properties, making it very suitable for photoelectrochemical water splitting as a photocathode. Here, a green and easy‐to‐operate solution method is introduced for preparing a compact Sb2Se3 film with preferred crystallographic orientation. The Sb2Se3 photocathode with [221] preferred orientation exhibits a photocurrent density of 11.3 mA cm−2 at 0 VRHE.