Boron and phosphorous-doped graphene as a metal-free electrocatalyst for the oxygen reduction reaction in alkaline medium

Abstract

An efficient solid-state pyrolysis route is presented to prepare boron- and phosphorous-doped graphene without using a template, solvent, or catalyst. By controlling the pyrolysis temperature, selective doping of phosphorous or boron was achieved. Phosphorous-doped graphene (PDG) and boron-doped graphene (BDG) samples are obtained when pyrolysing the precursor at 700 °C and at 900 °C, respectively under autogenic pressure. PDG and BDG electrodes show a considerable oxygen reduction activity by a direct four-electron pathway in alkaline medium. Further, these catalysts show improved durability under continuous oxygen reduction, resistance to methanol oxidation and CO-tolerance than the commercial catalyst. The results suggest that by tuning the reaction temperature, selective doping of either boron or phosphorous in graphene was achieved and the doped graphene samples were used as non-precious and metal-free catalysts for oxygen reduction.