Ternary PtRuFe nanoparticles supported N-doped graphene as an efficient bifunctional catalyst for methanol oxidation and oxygen reduction reactions

Abstract

In this study, we have synthesized N-doped graphene (NG) supported ternary PtRuFe nanocatalyst with size ranging from 2 to 3 nm using microwave-assisted polyol method and evaluated its electrochemical activity towards methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in direct methanol fuel cell (DMFC) and proton exchange membrane fuel cell (PEMFC), respectively. The as-prepared bifunctional PtRuFe/NG catalyst exhibited excellent electrocatalytic activity towards both MOR and ORR. During MOR, the PtRuFe/NG catalyst showed the stronger CO tolerance, lower onset potential, and higher methanol oxidation current than that of its un-doped counterpart (PtRuFe/rGO). In ORR, the catalyst exhibited higher oxygen reduction current with four electron transfer. The maximum power density delivered by PEMFC and DMFC using PtRuFe/NG were 870 and 112 mW cm−2, respectively, which are 25% higher than that of its un-doped counterpart. Also PtRuFe/NG showed 2- to 3-fold improvement in MOR, ORR, PEMFC and DMFC performances as compared with previously reported values of mono-, bi-, and tri-metallic catalysts supported on NG and other carbon substrates. The enhanced electrochemical activity may be attributed to the synergetic effect of nitrogen-doping along with the bi-functional and ligand effects of alloying low-cost Fe with Pt and Ru. The bifunctional ternary PtRuFe nanocatalysts supported on N-doped graphene has excellent potential to catalyze both MOR and ORR with remarkable reduction in the processing cost of fuel cells which is the primary problem facing the commercialization of fuel cells.