Abstract
In spite of their low cost, high activity, and diversity, metal oxide catalysts have not been widely applied in vanadium redox reactions due to their poor conductivity and low surface area. Herein, SnO2/reduced graphene oxide (SnO2/rGO) composite was prepared by a sol–gel method followed by high-temperature carbonization. SnO2/rGO shows better electrochemical catalysis for both redox reactions of VO2+/VO2+ and V2+/V3+ couples as compared to SnO2 and graphene oxide. This is attributed to the fact that reduced graphene oxide is employed as carbon support featuring excellent conductivity and a large surface area, which offers fast electron transfer and a large reaction place towards vanadium redox reaction. Moreover, SnO2 has excellent electrochemical activity and wettability, which also boost the electrochemical kinetics of redox reaction. In brief, the electrochemical properties for vanadium redox reactions are boosted in terms of diffusion, charge transfer, and electron transport processes systematically. Next, SnO2/rGO can increase the energy storage performance of cells, including higher discharge electrolyte utilization and lower electrochemical polarization. At 150 mA cm−2, the energy efficiency of a modified cell is 69.8%, which is increased by 5.7% compared with a pristine one. This work provides a promising method to develop composite catalysts of carbon materials and metal oxide for vanadium redox reactions.
Highlights
With the development of industrial processes, energy consumption is increasing day by day
Energy storage equipment is needed to store and transform the electric energy generated by renewable energy sources to realize its large-scale application [16,17,18,19,20]
The copper nanoparticle was an excellent catalyst for a V3+ /V2+ redox reaction, and improved the energy efficiency of the vanadium redox flow battery (VRFB)
Summary
With the development of industrial processes, energy consumption is increasing day by day. Some biomass-based carbon materials derived from glucose, fish scales, and kiwi fruit have abundant groups, heteroatoms, and a large surface area, which show certain electrochemical catalysts for a vanadium redox reaction [31,32]. The copper nanoparticle was an excellent catalyst for a V3+ /V2+ redox reaction, and improved the energy efficiency of the VRFB. It is an efficient way to obtain high-performance catalysts by compositing carbon materials and metal oxide. Graphene has good electrical conductivity, high stability, and a large surface area, making it an excellent electrocatalyst carbon support. The large surface area of reduced graphene oxide makes the SnO2 nanoparticle more dispersive, and provides a larger reaction place for redox reaction. Due to the synergy between SnO2 and reduced graphene oxide, the composite catalyst has good electrochemical activity and stability
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