Researching advancements in the electrochemical performance of molybdenum-based spherical polyoxometalate/reduced graphene oxide aerogel composites as electrode materials for supercapacitors

Abstract

A composite aerogel formed using spherical polyoxometalate {Mo₁₃₂} and graphene exhibits characteristics distinct from those of other aerogels. It retains the three-dimensional mesoporous channels typical of graphene aerogels and incorporates {Mo₁₃₂}-derived micropores. These structural features together furnish additional ion-transport channels for conductive particles. This aerogel material showcases a substantial specific surface area (207.114 m² g⁻¹), which is significantly higher than the of pure graphene aerogel (96.327 m² g⁻¹), indicating that the material has a rich microporous structure. The existence of {Mo₁₃₂} reduced the charge transfer resistance R_ct of the material to varying degrees, reaching a minimum of 1.916 Ω, far lower than the 2.861 Ω of the pure graphene aerogel, which further explains the role of mesopores. At a current density of 10 A g⁻¹ and after 10 000 cycles, the Coulomb efficiency of the material remained at 77.97%. A symmetrical supercapacitor is made of this aerogel material, with a specific capacitance of 100.6 F g⁻¹ at a current density of 1 A g⁻¹. The energy density at a current density of 10 A g⁻¹ is approximately 13 Wh kg⁻¹, and the power density is approximately 7500 W kg⁻¹. The data suggest that the multi-stage pore structure of the new aerogel can not only provide high-density active sites and increase charge storage, but also reduce internal charge-transfer resistance and improve power density and cycling stability. This study presents a novel approach for exploring electrode materials for supercapacitors.