Improved Photoelectrochemical Hydrogen Gas Generation on Sb₂S₃ Films Modified with an Earth-Abundant MoS_x Co-Catalyst

Antimony(III) sulfide (Sb₂S₃) has recently emerged as an outstanding potential photoelectrode due to its superlative optoelectronic properties for light-driven water splitting application. However, the occurrence of the recombination process in this material is regarded as one of the main limiting factors to date. Herein, we greatly suppressed the occurrence of recombination and improved carrier transfer via photoelectrodepositing an earth-abundant MoS_x co-catalyst over Sb₂S₃ films. The Sb₂S₃/MoS_x films displayed a remarkable 2-fold increase of their photoresponse for H₂ generation and also resulted in shifting the onset potential approximately 100 mV to less negative values. Based on an in-depth analysis of the transients’ photocurrent density, the enhanced photoresponse was assigned to a smaller probability of the electron–hole recombination process, as noted from the substantial reduction of the accumulated negative charge density values at the surface of the Sb₂S₃ films. The minimization of carriers recombination was also verified from the decrease of the charge transfer resistance values by approximately 2-fold for the Sb₂S₂/MoS_x films. Additionally, Sb₂S₃/MoS_x featured an increase of the space charge thickness, which suggests an improvement of carrier separation or a minimized recombination process due to the enlarged gradient of the (quasi-)Fermi level in the space charge region of the Sb₂S₃ films.