Heterostructured Co/Mo-sulfide catalyst enables unbiased solar water splitting by integration with perovskite solar cells

Cost-effective and highly abundant oxygen evolution reaction (OER) electrocatalysts are of tremendous research interest in a variety of energy storage and conversion technology fields. However, the commercial applications are greatly impeded due to the sluggish OER kinetics. Herein, a heterostructured Co9S8 @MoS2 electrocatalyst is demonstrated by elaborately implanting polyoxometalate of PMo12 into zeolitic imidazolate frameworks (ZIFs). The implantation of Mo species creates abundant Co9S8/MoS2 hetero-interfaces that could fine-tune the electrocatalytic activity of cobalt sites and thereof enhance the OER activity. Density functional theory (DFT) results prove synergetic effects between Co9S8 and MoS2 at the heterotinterfaces. The heterostructured Co9S8 @MoS2 catalyst achieves a low overpotential of 242 mV to reach 10 mA cm-2 and the corresponding Tafel slope is as small as 58 mV dec-1. Based on the superior OER activity, an unbiased solar water splitting system is built by integrating perovskite solar cell with the two-electrode Co9S8 @MoS2//Pt/C, yielding a high solar-to-hydrogen (STH) conversion efficiency of 13.6%. This study demonstrates a new approach for cost-effective solar water splitting system toward green hydrogen production. Heterostructured Co9S8 @MoS2 catalyst is designed to achieve a low overpotential of 242 mV at 10 mA cm-2 for OER. The high-performance OER electrode enables the integration of a perovskite solar cell–electrochemical water splitting system with a solar-to-hydrogen conversion efficiency of 13.6%. [Display omitted] •Heterostructured Co9S8 @MoS2 is designed for high-efficient oxygen evolution reaction.•DFT calculations verify the synergetic effects at the Co9S8 and MoS2 interfaces.•The Co9S8 @MoS2//Pt/C enables 1.52 V to drive 10 mA cm−2 for overall water splitting.•An unbiased solar water splitting system is built to show a STH efficiency of 13.6%.