Synergistic Catalysis of SnO₂-CNTs Composite for /VO²⁺ and V²⁺/V³⁺ Redox Reactions

In this study, a SnO₂-carbon nanotube (SnO₂-CNT) composite as a catalyst for vanadium redox flow battery (VRFB) was prepared using a sol-gel method. The effects of this composite on the electrochemical performance of $$ /VO²⁺, and on the V²⁺/V³⁺ redox reactions and VRFB performance were investigated. The SnO₂-CNT composite has better catalytic activity than pure SnO₂ and CNT due to the synergistic catalysis of SnO₂ and the CNT. SnO₂ mainly provides the catalytic active sites and the CNTs mainly provide the three-dimensional structure and high electrical conductivity. Therefore, the SnO₂-CNT composite has a larger specific surface area and an excellent synergistic catalytic performance. For cell performance, it was found that the SnO₂-CNT cell shows a greater discharge capacity and energy efficiency. In particular, at 150 mA cm^-2, the discharge capacity of the SnO₂-CNT cell is 28.6 mAh higher than that of the pristine cell. The energy efficiency of the modified cell (7%) is 7.2% higher than that of the pristine cell (62.8%). This study shows that the SnO₂-CNT is an efficient and promising catalyst for VRFB.