Nitrogen-Doped Porous Graphene-like Carbon Nanosheets as Efficient Oxygen Reduction Reaction Catalysts under Alkaline and Acidic Conditions

Abstract

Electrocatalysts are vulnerable to be influenced during the oxygen reduction reaction (ORR) process on the cathodes of direct methanol fuel cells, mainly by the reaction products and air-containing traces of acidic gas carbon dioxide (CO₂), leading to low activity and durability. Herein, an ORR catalyst was derived from furfural, nitrogen carbide (g-C₃N₄), and calcium chloride (CaCl₂) via a dual-template method, resulting in two-dimensional graphene-like carbon nanosheets with a micro–mesoporous architecture, large Brunauer–Emmett–Teller surface areas (748 m²/g), an ultrahigh pyridinic nitrogen-doping level (13.6 wt %), and high degree of graphitization. The as-synthesized sample shows high ORR performance and robust durability in both alkaline and acidic electrolytes undergoing a gas mixture of O₂ and CO₂ (95:5), demonstrating a strong tolerance of CO₂ during the ORR process. Besides, the as-prepared material also exhibits competitive properties in the selective capture of CO₂ gas versus N₂. Thus, this work provides a facile route of preparing high-performance bifunctional carbonaceous materials in both ORR and CO₂ gas capture.