Structural Engineering of Ultrathin ReS₂ on Hierarchically Architectured Graphene for Enhanced Oxygen Reduction

Herein, binary heteronanosheets made of ultrathin ReS₂ nanosheets and reduced graphene oxide (RGO) with either a two-dimensional (2D) "sheet-on-sheet" architecture (2D ReS₂/RGO) or a three-dimensional hierarchical structure (3D ReS₂/RGO) are constructed through rational structure-engineering strategies. In the resultant 3D ReS₂/RGO heteronanosheets, the ultrathin ReS₂ nanosheets are bridged on the RGO surface through Re-O bonds in a vertically oriented manner, which endows the heteronanosheets with open frameworks and a hierarchical porous structure. In sharp contrast to the 2D ReS₂/RGO, the 3D ReS₂/RGO heteronanosheets are featured with abundant active sites and channels for efficient electrolyte ions transport. This, coupled with the strong affinity toward oxygen-containing intermediates intrinsically associated with the binary ReS₂/RGO structure, imparts excellent oxygen reduction performance to the 3D ReS₂/RGO heteronanosheets for potential applications in fuel cells and metal-air batteries.