Pt-free MoS ₂ co-catalyst enables record photocurrent density in Sb ₂ Se ₃ photocathodes for highly efficient solar hydrogen production

Antimony selenide (Sb₂Se₃) emerges as a potential light-absorbing material for thin film photovoltaics and photoelectrochemical (PEC) water-splitting devices, due to its earth-abundant constituents and excellent photoelectric properties. However, losses caused by corrosion and sluggish charge transfer at the semiconductor/electrolyte interface require a co-catalyst to enhance these kinetic factors. In this study, MoS₂ is employed as a cost-effective, noble-metal-free catalyst to enhance the photocurrent density (<i>J</i> _ph), half-cell solar-to-hydrogen (HC-STH) conversion efficiency and stability of Sb₂Se₃-based photocathodes. Optimized thermodynamic/kinetic physical vapor deposition of MoS₂ substantially improves PEC performance, resulting champion Mo/Sb₂Se₃/CdS/MoS₂ photocathode that achieves a record <i>J</i> _ph of 31.03 mA cm^-2 at 0 <i>V</i> _RHE and the highest HC-STH efficiency of 3.08%, along with stability for over 5 hours in an acidic (pH 1) buffer solution. It is systematically revealed that MoS₂ reduces the photo-corrosion effect, decreases electron-hole recombination, and provides a significant increase in charge transfer efficiency at the semiconductor/electrolyte interface. This work highlights the potential of cost-effective, high-performance Sb₂Se₃-based photocathodes in advancing efficient PEC devices for solar hydrogen production.