Core-shell heterostructure by coupling layered ReS₂ with Co₉S₈ nanocubes for boosted oxygen evolution reaction

The controllable morphology and composition of catalysts are crucial to improving the electrocatalytic activity of oxygen evolution reaction (OER). Herein, we construct a bimetallic heterostructure by sulfidation and hydrothermal methods, and the layered ReS₂ is vertically aligned on Prussian blue-derived hollow Co₉S₈ nanocubes (Co₉S₈@ReS₂). The core-shell structure of Co₉S₈@ReS₂ can effectively prevent the restacking of layered ReS₂, expose the abundant surface area and improve the utilization of electrocatalytic sites, resulting in fast electrolyte diffusion and charge transfer during OER. Due to the synergistic effect of the core-shell morphology and the formed bimetallic heterostructure, Co₉S₈@ReS₂ exhibits excellent catalytic OER performance. At 10 mA/cm², only 288 mV of overpotential is required with the Tafel slope of 73.3 mV/dec for Co₉S₈@ReS₂, which are both lower than that of Co₉S₈ and ReS₂. Meanwhile, Co₉S₈@ReS₂ exhibits high catalytic stability and low charge transfer resistance and the boosted active sites are confirmed by density functional theory. This work provides a rational design of the OER catalysts by constructing the bimetallic heterostructure.