A promising catalyst for catalytic reduction of V2O5 to synthesize the V3.5+ electrolytes for vanadium flow batteries

Preparing the V 3.5+ electrolytes by catalytic reduction of V 2 O 5 with formic acid is a straightforward and efficient process for vanadium flow batteries (VFBs). Nevertheless, converting vanadium ions in a strong acid environment depends on utilizing highly active and stable catalysts. Herein, a novel Pt-based catalyst supported by graphene oxide (GO) and hexadecyl trimethyl ammonium bromide (CTAB) (Pt/GO@CTAB) was developed for the catalytic reduction method. The introduction of CTAB into the catalyst enhanced the dispersion of GO, increased the degree of defects, and created more reduction sites for Pt, thereby improving the catalytic activity for formic acid oxidation. As a result, the reduction rate increased by 42.86 % compared to the Pt/C catalyst. Moreover, an economic analysis of the catalyst revealed that Pt/GO@CTAB could reduce costs by 49.25 %. Finally, charge-discharge experiments were conducted on the VFB single-cell with the prepared V 3.5+ electrolyte, which exhibited comparable Coulombic efficiency (CE) and energy efficiency (EE) to the other electrolytes, with CE and EE values of approximately 97 % and 87 %, respectively. These results suggest that Pt/GO@CTAB is a promising catalyst that not only reduces costs but also maintains electrolyte performance, offering a viable alternative to the traditional Pt/C catalyst for the efficient preparation of vanadium electrolytes.