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

<p>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 Sb<sub>2</sub>Se<sub>3</sub>–fabricated by a simple, low temperature selenization of electrodeposited Sb–is intrinsically stable towards photocorrosion in strongly acidic media (1 M H<sub>2</sub>SO<sub>4</sub>). Coupling with a photoelectrodeposited MoS<sub>x</sub> hydrogen evolution catalyst gives high photocurrents (5 mA cm<sup>-2</sup> at 0 V vs RHE) and high stability without protective layers (10 h with ~20% loss). A low temperature sulfurization of the Sb<sub>2</sub>Se<sub>3</sub>-MoS<sub>x</sub> stack dramatically improved the onset potential, resulting in high photocurrent densities up to 16 mA cm<sup>-2</sup> at 0 V vs RHE. The simplicity with which these photocathodes are fabricated, combined with the high photocurrents and stability, make Sb<sub>2</sub>Se<sub>3</sub> a strong candidate for scalable PEC cells.</p>