A highly active and stable electrocatalyst for the oxygen reduction reaction based on a graphene-supported g-C3N4@cobalt oxide core–shell hybrid in alkaline solution

Abstract

A novel hybrid, with g-C₃N₄ embedded CoO particles covalently supported on a two-dimensional graphene sheet, is synthesized by a facile and scalable method towards the oxygen reduction reaction (ORR) for fuel cells. The composite hybrid with a suitable loading of g-C₃N₄@cobalt oxide on graphene exhibits excellent electrocatalytic activity and a dominant four-electron oxygen reduction pathway in basic solution. The kinetic-limiting current density (J_k) is 16.78 mA cm⁻² at −0.25 V, approaching that of 20% Pt–C (17.22 mA cm⁻²) at the same potential. The performance gap between the hybrid and 20% Pt–C in terms of the half-wave potential difference (ΔE_½) is 25 mV in alkaline solution. Furthermore, the hybrid is robust and methanol tolerant, making it a good candidate as a cathodic electrocatalyst in fuel cells.