Synthesis of nitrogen-doped mesoporous carbon nanosheets for oxygen reduction electrocatalytic activity enhancement in acid and alkaline media

Abstract

In the present work, nitrogen-doped mesoporous carbon nanosheets (NMCNs) are prepared and extensively investigated for the oxygen reduction reaction. Initially, by using dual templates, viz. graphene oxide and a cationic surfactant, silica films (thickness: 1.0 nm) are synthesized and characterized using transmission electron microscope (TEM), nitrogen adsorption-desorption (N2 ad/des) measurements, and small-angle X-ray diffraction (SA-XRD). Morphology and structure of silica evolve along with graphene oxide concentration, while the co-operative assembly and the final structure are determined by the electrostatic interaction between the dual templates. The effect of silica template on the resultant NMCNs is investigated physicochemically by photoelectron spectroscopy (XPS), TEM, N2 ad/des and electrochemically by cyclic voltammetry (CV), and linear sweep voltammetry (LSV). NMCNs are featured of a high content of nitrogen dopant, high specific surface area (SSA) and ultrathin thickness (1.5 nm), favoring catalysis and facilitating the mass transport of the reactive species. From the electrochemical tests, it is confirmed that NMCNs yield a high oxygen reduction reaction (ORR) electrocatalytic activity in acid and alkaline environment; this activity is similar or even better as compared with the one measured over carbon supported platinum commercial catalyst (40 wt % Pt/C). © 2018 Hydrogen Energy Publications LLC