In Situ Growth of Reduced Graphene Oxide Ultrathin Nanosheets on the Surface of Co9s8 Dodecahedral Hollow Cage with Enhanced Oxygen Evolution Reaction and Mechanism Insight

Even today, the development of effective and economical electrocatalysts for the slow oxygen evolution reactions is still the most critical bottleneck for the preparation of clean-energy H2 by water splitting. The ZIF-67 dodecahedron used as a template in this paper to prepare Co9S8 with a hollow dodecahedron structure using the hydrothermal method and the tubular furnace calcination method to shorten the charge transport path and increase its specific surface. Subsequently, ultrathin nanosheets of reduced graphene oxide (rGO) (folded structure) were grown on the surface of the Co9S8 dodecahedron to prepare effective electrocatalysts, and their specific structure, chemical composition, morphology, and surface area were systematically characterized. The photocatalytic performance of the Co9S8@rGO hollow heterostructure was first investigated by changing the amount of reduced graphene oxide loading. The photocatalytic performance of the 30% Co9S8@rGO hollow heterostructure was found to be superior to that of the Co9S8 single component, indicating that both the hollow Co9S8 structure and the ultrathin rGO nanosheet composite had a synergistic effect. It is worth mentioning that rGO had a high conductivity, a large specific surface area, and a mesoporous structure. Therefore, the Co9S8@rGO electrocatalyst was manufactured by modifying the Co9S8 dodecahedral cage with rGO nanosheets, and its OER properties were further investigated. By uniformly loading an appropriate amount of rGO nanosheets onto the Co9S8 surface, the overpotential of the 30% Co9S8@rGO hollow heterostructure was successfully reduced to 190 mV (10 mA cm-2). Meanwhile, the Tafel slope was reduced to 66.48 mV dec-1. The increased OER activity was probably due to introduction rGO nanosheets, which improved the electrical conductivity and increased the active site.