Efficient Solar-to-Hydrogen Conversion from Neutral Electrolytes using Morphology-Controlled Sb₂Se₃ Light Absorbers

We present a novel solution-based synthesis method enabling the morphology variation of Sb2Se3 light absorbers. The morphology of Sb2Se3 films varies from dense particulate planar films to one-dimensional nanowire-stacked films upon modulating the Sb and Se molar ratio in the precursor ink. The effect of morphology and crystallographic orientation on the electrical and consequently the PEC properties of Sb2Se3-based photocathodes is investigated. Sequential deposition of CdS as a buffer layer with TiO2 and Pt enables us to build a favorable band structure. An onset potential of 0.47 V versus a reversible hydrogen electrode (RHE) is observed with 13.5 mA cm–2 at 0 V versus a RHE under air mass 1.5 global illumination in a pH 1 electrolyte. In addition, the surface-modified photocathode stably produces hydrogen with a photocurrent of 11 mA cm–2 at 0 V versus RHE in a neutral electrolyte, thus demonstrating the promising potential of the proposed Sb2Se3 photocathodes as efficient PEC water-splitting devices.