Unveiling the enhanced performance of non-platinum based hybrid nanocomposites for selective electrocatalytic oxygen reduction

Abstract

Hierarchical multi walled carbon nanotubes (MWCNT) anchored manganese dioxide (MnO2) hybrid electrocatalyst have been prepared employing a simple solution route. The crystal structure and the morphology of products were investigated using powder X-ray diffraction (XRD), infrared spectroscopy (IR), field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrocatalytic behavior for the oxygen reduction reaction (ORR) was evaluated using linear sweep voltammetry (LSV) and rotating ring disc electrode (RRDE) experiments. The hierarchical MWCNT wrap over MnO2 creating 3D network structures which has significant impact on the performance of oxygen reduction reaction. The onset potentials of MnO2 and MnO2/MWCNT are found to be −0.24 and −0.29 V respectively, indicating the good ORR activity of MnO2/MWCNT in alkaline medium. The number of electrons involved in the ORR is obtained 3.98 for MnO2/MWCNT and 2.91 for hollow sphere MnO2. Moreover MnO2/MWCNT composite shows better ORR selectivity in presence of methanol than that of bench mark Pt/C electrocatalyst. This enhanced electro catalytic behavior is mainly attributed to the synergism araised between the MnO2 and MWCNT.