Commercialization of energy storage and conversion devices depends critically on affordable transition metal-based oxygen reduction reaction (ORR) catalysts. This is due to the high cost and poor stability of state-of-the-art Pt-based electrocatalysts. In this context, TM-based ORR catalysts have gained tremendous interest due to their Pt-like ORR behavior and considerably high stability. In this study, a unique electrocatalyst made of the transition metal Vanadium (V) has been proposed as an efficient electrocatalyst in combination with N-doped carbon, potentially creating V–Nx–C-type active centers. The V insertion is achieved by using inorganic metal–organic frameworks as precursors. A systematic evaluation of the effect of V content on morphological and electrocatalytic ORR activity has been established via RDE studies. The resulting optimized V–N–C-35 catalyst has shown excellent ORR activity and stability in a 0.1 M KOH electrolyte. XRD, SEM, and TEM analyses reveal highly dispersed V species on the N-doped carbon matrix, and XPS analysis reveals the possible V–Nx–C and OH–V–Nx–C types of ORR active sites. The electrochemical ORR studies revealed the V–Nx–C-35 catalyst exhibited highest ORR activity with a 0.905 V half-wave potential and excellent stability, showing a loss of 5 mV for 5000 potential cycles. When applied as a cathode catalyst in aqueous Zn–Air batteries, the V–N–C-35 catalyst exhibits a power density of ∼70 mW cm–2 and a specific capacity of 447 mA·h·gzn–1, slightly higher than the Pt/C catalyst under similar operating conditions. These results indicate that V–Nx–C-35 could serve as an alternative electrocatalyst for energy storage devices like Zn–air batteries.
Peera et al. (Thu,) studied this question.