Enlightening the performance-boosting effect of electroactivation approaches on the electrooxidation of methanol reaction in acidic media catalyzed by cobalt-tin bimetallic nanocatalysts

Abstract

This research investigates the impact of electrochemical activation on cobalt-tin (Cox-Sn100-x) bimetallic nanocatalysts for the methanol oxidation reaction (MOR) in acidic conditions. Two electroactivation protocols, namely activation in a phosphate buffer (PB) solution and in-situ activation, using chronoamperometry, were developed. The electrochemical performance of the MOR electrocatalyst was evaluated through cyclic voltammetry analysis within a specific electrode potential range. Optimal activation conditions for the PB solution were achieved at a pH of 3.0 and an activation potential of −1.3 V (vs. Ag/AgCl), while the in-situ activation process showed the best results at an activation potential of −0.7 V (vs. Ag/AgCl). Both the in-situ and PB electroactivated Co65–Sn35 catalysts exhibited significant enhancements in MOR activity, with the in-situ activation resulting in a 10-fold increase and the PB activation leading to an 8.5-fold increase. The proposed mechanism for this substantial enhancement involves simultaneous hydrogen evolution and water electrolysis during the electroactivation treatments of the Co65–Sn35 electrocatalyst. In fact, the formation of OHads species during the electroactivation treatment could provide a fraction of OHads which was essential for the MOR. These findings might present opportunities for the engineering and design of bimetallic noble metal-free nanocatalysts for efficient utilization in high-performance acidic direct methanol fuel cells (DMFCs).