Pt-Free MoS2 Co-Catalyst Enables Record Photocurrent Density in Sb2Se3 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 produced 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 (J_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 achieves a record J_ph of 31.03 mA cm⁻² at 0 V_RHE, highest HC-STH efficiency of 3.08%, along with over 5 hours of stability in acidic (pH1) buffer solution. It is systematically revealed that the 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.