Synthesis and electrocatalytic performance of a P-Mo-V Keggin heteropolyacid modified Ag@Pt/MWCNTs catalyst for oxygen reduction in proton exchange membrane fuel cell

Abstract

In this study, the Keggin type molybdovanadophosphoric acid (PMo12-xVxO40 (x = 1,2,3), abbreviated as PMoV) modified on Ag@Pt/MWCNTs composite catalysts were successfully prepared by a chemical impregnation method. The results of physical characterization revealed that PMoV molecules were incorporated into the Ag@Pt/MWCNTs structure. The effect of the composite catalyst on oxygen reduction was studied by electrochemical analysis. The catalytic performance of the composite catalyst changed with the change of the number of the substituted vanadium atoms in the heteropolyacid. The PMo10V2 catalyst shows the best activity and stability among the three heteropolyacid-modified catalysts evaluated. When the optimum doping ratio is 20%, the electrochemically active surface area (ECSA) of the composite catalyst is 99.69 m2/gPt, and it is increased by 49.11% compared with commercial Pt/C catalysts (65.63 m2/gPt). The initial reduction potential of the composite catalyst is 0.968 V, which is shifted by 73 mV compared with the 20% Pt/C catalyst. Additionally, the mechanism of catalytic reaction is also investigated.