Effect of preparation routes on activity of Ag-MnOx/C as electrocatalysts for oxygen reduction reaction in alkaline media

The effect of preparation routes on the physical characteristics and activity of the Ag-MnOx/C composites toward the oxygen reduction reaction (ORR) in alkaline media were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersion spectroscopy (EDS) as well as scanning electron microscopy (SEM) and electrochemical techniques. The results show that more Ag and Mn species present on the surface of the Ag-MnOx/C composite prepared by two-step route (Ag-MnOx/C-2) compared to the one prepared by one-step route (Ag-MnOx/C-1), which contributes to its superior activity toward the ORR. The higher electron transfer number involved in the ORR can be observed on the Ag-MnOx/C-2 composite and its specific mass kinetic current at −0.6 V (vs Hg/HgO) is 46 mA/μg, which is 23 times that on the Ag/C. The peak power density of zinc-air battery with the Ag-MnOx/C-2 air electrode reaches up to 117 mW/cm2.