Nitrogen-doped carbon black as methanol tolerant electrocatalyst for oxygen reduction reaction in direct methanol fuel cells

Abstract

Nitrogen-doped metal free carbon catalysts were prepared via pyrolysis of polyaniline-coated carbon in different ratios with varying nitrogen content. The surface states and surface composition were investigated using XPS (X-ray photoelectron spectroscopy). XPS analysis confirms the presence of pyridinic and pyrollic nitrogen in the carbon network that is responsible for the oxygen reduction activity. The shift in onset potential of oxygen reduction on C:N (1:1) is ∼0.3V more positive compared to Vulcan carbon, shows improved activity toward oxygen reduction reaction in acidic electrolyte. Hydrodynamic voltammetric studies confirm that the reduction of oxygen follows the 4e− pathway which leads to the formation of water.