Boron-doped graphene-supported manganese oxide nanotubes as efficient non-metal catalyst for oxygen reduction reaction

Abstract

An efficient, low cost and non-precious hybrid metal catalyst compound, consisting of boron-doped graphene nanosheets (BGNS) and manganese oxide nanotube (MnO2) is used as a catalyst for oxygen reduction reaction (ORR). The morphological, chemical composition and electrochemical properties of the as-synthesized BGNS-MnO2 composite (MnO2@BGNS) were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, linear sweep voltammetry and rotating disk electrode (RDE). The asprepared BGNS-MnO2-modified glassy carbon electrode (GCE) displayed excellent catalytic activity towards ORR in an alkaline medium compared to the pure MnO2 and pure BGNS. In addition, the hybrid electrode exhibited superior electrocatalytic stability and preferable methanol tolerance compared to commercial platinum electrocatalyst in an alkaline media. This is due to the synergistic effect between the excellent catalytic activity of the MnO2 nanotubes and the large surface area and high conductivity of BGNS. Moreover, density functional theory (DFT) calculations show a strong binding energy between BGNS and MnO2 in the form of strong electrostatic interaction and inter charge transfer. The enhanced reactivity of MnO2@BGNS is due to the strong bonding between the boron (BGNS) and oxygen (MnO2). Moreover, the electron density difference and partial density of state (PDOS) analysis suggest that the electron transfer capability of B–O bonding is stronger than the C–O bonding. Finally, we conclude that boron doping of graphene is an effective strategy for fabricating an efficient ORR catalysts.