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.