One-step in-situ fabrication by pulsed laser deposition for enhancing stability of Sb2Se3 photocathode

Abstract

Antimony selenide (Sb2Se3) is an earth-abundant and low-cost photocathode material with favorable optoelectronic properties, including a narrow bandgap of 1.0-1.3 eV and strong visible-to-near-infrared absorption. However, Sb2Se3 typically shows limited operational stability in aqueous electrolytes, which is commonly associated with surface oxidation and increased interfacial recombination. Atomic layer deposition (ALD) titanium dioxide passivation mitigates photocorrosion, yet its low HER activity often necessitates wet cocatalyst loading that promotes interfacial Sb2O3 and degradation. Here, a durable Sb2Se3 photocathode is demonstrated using a bifunctional molybdenum disulfide (MoS2) overlayer integrated by one-step, in-situ pulsed laser deposition (PLD). Sequential growth of Sb2Se3 and MoS2 within a single vacuum chamber enables air-free and solvent-free fabrication, preserving a clean, oxide-free interface. The MoS2 overlayer provides both surface passivation and intrinsic HER catalysis, eliminating post-deposition wet processing. By tuning the MoS2 thickness, an optimal balance between interfacial protection and charge-transfer efficiency is achieved, enabling sufficient exposure of MoS2 edge sites that serve as active sites for hydrogen evolution. The optimized MoS2/Sb2Se3 photocathode shows an onset potential shift of approximately 80 mV and delivers-8.3 mA cm-2 at-0.3 V versus RHE, compared with-0.78 mA cm-2 for bare Sb2Se3. The photocathode retains over 65% of its initial photocurrent after 30 h of continuous operation in 0.5 M sulfuric acid.