Preparation Of MnO_x/rGO Composites And Their Electrocatalytic Properties For Oxygen Reduction Reaction

With the increasing demand of energy and depletion of traditional fossil fuels, it is of great significance to find new energy sources. Fuel cells have been widely considered as green and efficient alternative energy sources, which have gradually gained significant attention due to their high energy and power density. Efficient catalysts for the cathodic oxygen reduction reaction ?ORR? play a crucial role in the development of fuel cell technology. At present, Pt and its alloys have generally been considered as the most effective electrocatalysts for ORR in fuel cells. However, they suffer not only from the high cost of Pt but also from poor stability under the operating conditions. Furthermore, Pt-based electrocatalysts have poor tolerance against fuel crossover and carbon monoxide ?CO? poisoning. Thus, developing low-cost and efficient non-precious metal catalysts for ORR is essential. It is reported that graphene and manganese oxides for the oxygen reduction reaction have certain catalytic activity, which are expected to become cathode catalyst instead of platinum-based catalyst in fuel cell.In this paper, we prepared three different manganese oxide supported on reduced graphene oxide composites ?Mn₃O₄/rGO, MnO/rGO and MnOa/rGO? via hydrothermal method, thermal decomposition and electrochemical method, respectively. The size, morphology and crystal structure of the composites were characterized by scanning electron microscopy ?SEM?, transmission electron microscopy ?TEM? and X-ray powder diffraction ?XRD?. Their constituent and elements valence were analyzed through X-ray photoelectron spectroscopy ?XPS? and Raman spectroscopy ?Raman?. And the electrocatalytic properties for ORR in alkaline medium are investigated by cyclic voltammetry ?CV?, chronoamperometry ?I-t? and linear scanning voltammetry ?LSV?. The results showed that the as-prepared MnO_x/rGO composites exhibit high electrocatalytic activity toward ORR. Moreover, the composites show better stability than the commercial Pt/C catalyst.