Photocorrosion-Resistant Sb2Se3 Photocathodes with Earth Abundant MoSx Hydrogen Evolution Catalyst

The poor stability of high efficiency photoabsorber materials in aqueous media is one factor holding back the realization of photoelectrochemical (PEC) water splitting for large scale, practical solar fuels generation. Here, we demonstrate that highly efficient thin film Sb₂Se₃–fabricated by a simple, low temperature selenization of electrodeposited Sb–is intrinsically stable towards photocorrosion in strongly acidic media (1 M H₂SO₄). Coupling with a photoelectrodeposited MoS_x hydrogen evolution catalyst gives high photocurrents (5 mA cm^-2 at 0 V vs RHE) and high stability without protective layers (10 h with ~20% loss). A low temperature sulfurization of the Sb₂Se₃-MoS_x stack dramatically improved the onset potential, resulting in high photocurrent densities up to 16 mA cm^-2 at 0 V vs RHE. The simplicity with which these photocathodes are fabricated, combined with the high photocurrents and stability, make Sb₂Se₃ a strong candidate for scalable PEC cells.