Cross-linker mediated formation of sulfur-functionalized V₂O₅/graphene aerogels and their enhanced pseudocapacitive performance

The development of efficient synthesis methods for the preparation of vanadium oxide (V₂O₅)-graphene holds great promise considering the excellent performance of the composite in electrochemical applications. Herein, we report the cross-linking of a V₂O₅-graphene hybrid via a vanadium-thiourea redox system, which allowed the assembly of graphene oxide functional groups with V₂O₅ through the reducing ability of thiourea (TU) under room conditions within an impressively short reaction time (20 min). The resulting 3D composite aerogel forms a highly porous architecture of sulfur-functionalized interconnected networks. Such sulfur-functionalized transition metal oxide-graphene-based aerogels are excellent candidates in energy storage applications. When the vanadium oxide-graphene aerogel was evaluated as an electrode for a supercapacitor, a specific capacitance as high as 484.0 F g^-1 at 0.6 A g^-1 was obtained in a two-electrode cell configuration. This performance is much higher than that of the vanadium oxide-graphene aerogels prepared in the absence of thiourea. The vanadium oxide-graphene aerogel is able to deliver a remarkable energy density of 43.0 Wh kg^-1 at a power density of 0.48 kW kg^-1 at 0.6 A g^-1 and can hold 24.2 Wh kg^-1 at a maximum power density of 9.3 kW kg^-1 at 10 A g^-1. The symmetric supercapacitor assembled from the aerogel can retain 80% of its initial capacitance after 10000 cycles.