Nitrogen-doped carbon quantum dot/graphene hybrid nanocomposite as an efficient catalyst support for the oxygen reduction reaction

Abstract

A nitrogen-doped carbon quantum dot/graphene (N-CQD/G) hybrid nanocomposite was synthesized in-situ using a sacrificial template-assisted pyrolysis method with an oligomeric phenolic resin as the carbon source and dicyandiamide as the sacrificial template precursor/nitrogen source. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, atomic force microscopy, nitrogen adsorption–desorption, Raman and X-ray photoelectron spectroscopy were employed to characterize N-CQD/G samples. The Pt nanoparticles were then deposited onto N-CQD/G hybrids (Pt/N-CQD/G) using a polyol reduction method. Structural and morphological investigations for the Pt/N-GQD/G revealed that ultrafine Pt particles with an average size of 2.1 nm, together with CQDs, are uniformly dispersed on the surfaces of graphene nanosheets. Compared with commercial Pt/C catalysts, Pt/N-CQD/G with highly electrochemical active surface area (ca. 123.4 m2 g−1Pt) show remarkably enhanced electrocatalytic activity and durability toward oxygen reduction reaction (ORR). The superior ORR catalytic performance of Pt/N-CQD/G can be attributed to highly distributed Pt nanoparticles with small size, nitrogen-doping, and strong interaction between metal and support, as well as the unique structure of N-CQD/G hybrids which combines the advantages of both carbon quantum dot and graphene, such as abundant edges and doping sites, high surface area, large pore size and high electrical conductivity.