One-pot synthesis of boron-doped ordered mesoporous carbons as efficient electrocatalysts for the oxygen reduction reaction

Abstract

Boron-doped ordered mesoporous carbons (B-OMCs) with a tunable and high level of doping content (>1 wt%) have been synthesized via a one-pot solvent evaporation induced self-assembly (EISA) process. The as-prepared B-OMCs show a highly ordered 2D hexagonal mesostructure with an average pore size of 3.4–4.0 nm, which could facilitate an efficient mass transport of O₂ and electrolyte during the oxygen reduciton reaction (ORR) process. The electrochemical investigations demonstrate that B-doping could significantly enhance the electrocatalytic activity of the carbon materials for the ORR in alkaline media. Specifically, the B-OMCs with a boron doping content of 1.17 wt% show the highest electrocatalytic activity and best long-term durability for ORR as compared to the non-doped OMCs and the B-OMCs with other doping contents. Combined with various physical characetrizations including X-ray diffraction, small angle X-ray scattering, N₂ physisorption, Raman spectroscopy and X-ray photoelectron spectroscopy, the enhanced catalytic performance of the B-OMCs could be ascribed to the synergistic effects of the ordered mesostructure, specific surface area and moderate boron doping. This work not only helps the fundamental understanding of the correlation between the catalytic performance and the morphology, structure of the OMCs and the doping extent of heteroatoms, but also shows the promising potential applications of the B-OMCs as efficient, low-cost catalysts in metal-air batteries and fuel cells.