Graphitic carbon nitride on reduced graphene oxide prepared via semi-closed pyrolysis as electrocatalyst for oxygen reduction reaction

Abstract

Graphitic carbon nitride (g-C3N4)/graphene hybrids were shown to be promising low-cost and durable substitutes for Pt-based oxygen reduction reaction (ORR) electrocatalysts in metal-air batteries and fuel cells. However, most of the synthesis procedures found in the literature are tedious, resource-intensive, and make use of toxic precursors. In this paper, we present a facile method for preparing g-C3N4 on reduced graphene oxide (g-C3N4@rGO) via semi-closed pyrolysis of graphene oxide and urea under an ambient air atmosphere. The resulting electrocatalyst was characterized using microscopic, structural, and spectroscopic techniques. Electrochemical characterization showed that the onset and half-wave potentials (vs. Ag/AgCl), as well as ORR electron transfer number, were found to be – 0.248 V, – 0.281 V, and 3.16, respectively. Although g-C3N4@rGO has relatively lower electrocatalytic activity compared to Pt/C, the former was shown to exhibit better electrochemical stability. Nonetheless, the low-cost and more sustainable method of manufacturing g-C3N4@rGO in this study advances the economic viability of carbon-based ORR electrocatalysts.