A remarkable three-component RuO2-MnCo2O4/rGO nanocatalyst towards methanol electrooxidation

Abstract

A three-part nano-catalyst including ruthenium oxide, manganese cobalt oxide, and reduced graphene oxide nanosheet in form of RuO2-MnCo2O4/rGO is synthesized by one-step hydrothermal synthesis. The material is placed on a glassy carbon electrode (GCE) for electrochemical studies. The ability of these nano-catalysts in the oxidation process of methanol in an alkaline medium for usage in direct methanol fuel cells (DMFC) was examined with electrochemical tests of cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The effect of the addition of rGO to the nanocatalyst structure in the methanol oxidation reaction (MOR) process was investigated. We introduced the RuO2-MnCo2O4/rGO as a nanocatalyst with excellent cyclic stability of 97% after 5000 cycles in the MOR process. Besides, the study of the Tafel plots and the effect of temperature and scan rate in the MOR process showed that RuO2-MnCo2O4/rGO nanocatalyst has better electrochemical properties than MnCo2O4 and RuO2-MnCo2O4. This high electrocatalytic activity could be related to the synergistic effect of placement of metal oxides of ruthenium, manganese, and cobalt near each other and putting them on rGO, which enhances conductivity and surface area and improve electron transfer. The decrease in the resistance against charge transfer and the increment in the anodic current density illustrated that the reaction rate is enhanced at higher temperature. Thus RuO2-MnCo2O4/rGO shows robust stability and superior performance for MOR.