Tin dioxide as a high-performance catalyst towards Ce(vi)/Ce(iii) redox reactions for redox flow battery applications

Abstract

A novel SnO₂-modified graphite felt electrode with a high-performance and non-precious electrocatalyst of SnO₂ deposited onto the graphite felt surface is prepared for cerium-based redox flow batteries (RFBs). Through a facile and one-pot solvothermal route, a thin and uniform SnO₂ coating layer could be successfully introduced onto the surfaces of graphite felt fibers for the first time. The electrochemical reactivity of the SnO₂ decorated graphite felt toward the redox reactions of Ce(IV)/Ce(III) could be substantially enhanced, which is ascribed to the superior electrocatalytic activity of this SnO₂ catalyst. What is more, the undesirable side reaction of oxygen evolution can be suppressed by introducing the SnO₂ coating layer that possesses a high oxygen evolution overpotential. The charge/discharge test with the catalyzed electrode exhibits a 41.2% and 25.1% increase in energy efficiency as compared with the pristine graphite felt and acid treated graphite felt at a high current density of 30 mA cm⁻². Also, the long-term cycling performance confirms the outstanding stability of the as-prepared SnO₂ catalyst enhanced electrode. These results suggest that the graphite felt modified by the low-cost and uniform SnO₂ coating layer could serve as a highly promising electrode towards the Ce(IV)/Ce(III) redox couple for cerium-based RFB applications.