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

摘要

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_(1/2)) 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.