The Composites Of Bimetallic Oxides/N-doped Graphene As High-efficient Oxygen Reduction Catalysts

With the increasing global energy crises, renewable and sustainable new energy resources have been paid close attention due to their promising high energy density and rare environmental damage compared to traditional fossil energy. In the electrochemical cell, the oxygen reduction reaction on cathode is the fundamental reaction, and it notably determines the efficiency of a fuel cell.In fuel cells, Pt and its alloys are the most reliable electrocatalysts for the ORR. Nevertheless, the high-cost and exiguity of Pt hamper its extensive commercial application as the electrocatalysts for the ORR. Therefore, it is expected that low-cost and high-performance electrocatalytic materials can be prepared to replace the expensive Pt-based electrocatalysts.The novel nanocomposites of double metal oxide/nitrogen doped graphene with polyaniline as nitrogen source were prepared by the conjunction of hydrothermal treatment and pyrolysis. The morphologies and structures of the as-prepared samples were characterized by TEM, XPS, XRD and Raman, respectively. The electrocatalytic performance of the fabricated composites towards the oxygen reduction reaction(ORR) was evaluated employing CV, LSV, RRDE and i-t methods. The results show that the CoFe2O4/N-G 800 and NiCo2O4/N-G 900 composites for the ORR possessed good activity, close to Pt/C. The long-term stability and tolerance to methanol crossover for our fabricated two catalysts were obviously better than those of Pt/C. The as-prepared double metal oxide/nitrogen doped graphene hybrids are possibly used as cathode catalysts for application in direct methanol fuel cells(DMFCs).