Nitrogen, phosphorus and sulfur co-doped ultrathin carbon nanosheets as a metal-free catalyst for selective oxidation of aromatic alkanes and the oxygen reduction reaction

Abstract

Carbon materials have attracted considerable interest as metal-free heterogeneous catalysts owing to their superior physicochemical properties, including low cost, stability, and easily tailorable structures as well as excellent catalytic activity. In this study, we have designed an efficient method to produce ultrathin carbon nanosheets (∼2.2 nm) with multi-heteroatom (nitrogen, phosphorus and sulfur) doping and a high surface area (up to 1198 m² g⁻¹). This method employs poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) as the main carbon source and N,P,S-doping sources, while g-C₃N₄ nanosheets act as the morphology template, extra N doping source and porogen. The doped carbon nanosheets are an excellent metal-free carbocatalyst for selective oxidation of aromatic alkanes in aqueous solution and electrochemical catalyst for the oxygen reduction reaction in an alkaline medium.