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. Sb 2 Se 3 , 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 Sb 2 Se 3 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 Sb 2 Se 3 film with a preferred orientation, resulting in rapid charge transport and high photocurrent. After depositing TiO 2 and Pt in turn, the photocathode with a structure of FTO/Au/Sb 2 Se 3 /TiO 2 /Pt exhibits a photocurrent density of 11.3 mA cm −2 at 0 V RHE . An unassisted solar water splitting device integrating the Sb 2 Se 3 ‐based photocathode with an inorganic perovskite photovoltaic cell achieves a solar‐to‐hydrogen efficiency of 2.45%. The efficient Sb 2 Se 3 ‐based photocathode shows promising potential for solar fuel production.