Fe–Mn bimetallic oxides-catalyzed oxygen reduction reaction in alkaline direct methanol fuel cells

Two Fe–Mn bimetallic oxides were synthesized through a facile solvothermal method without using any templates. Fe(2)O(3)/Mn(2)O(3) is made up of Fe(2)O(3) and Mn(2)O(3) as confirmed via XRD. TEM and HRTEM observations show Fe(2)O(3) nanoparticles uniformly dispersed on the Mn(2)O(3) substrate and a distinct heterojunction boundary between Fe(2)O(3) nanoparticles and Mn(2)O(3) substrate. MnFe(2)O(4) as a pure phase sample was also prepared and investigated in this study. The current densities in CV tests were normalized to their corresponding surface area to exclude the effect of their specific surface area. Direct methanol fuel cells (DMFCs) were equipped with bimetallic oxides as cathode catalyst, PtRu/C as the anode catalyst and PFM as the electrolyte film. CV and DMFC tests show that Fe(2)O(3)/Mn(2)O(3)(3 : 1) exhibits higher oxygen reduction reaction (ORR) activity than Fe(2)O(3)/Mn(2)O(3)(1 : 1), Fe(2)O(3)/Mn(2)O(3)(1 : 3), Fe(2)O(3)/Mn(2)O(3)(5 : 1) and MnFe(2)O(4). The much superior catalytic performance is due to its larger surface area, the existence of numerous heterojunction interfaces and the synergistic effect between Fe(2)O(3) and Mn(2)O(3), which can provide numerous catalytic active sites, accelerate mass transfer, and increase ORR efficiency.