One-pot synthesis of nitrogen-rich carbon dots decorated graphene oxide as metal-free electrocatalyst for oxygen reduction reaction.

In this study, nitrogen-rich carbon dots decorated graphene oxide (N- C dots/GO) hybrid, as a metal-free electrocatalyst for oxygen reduction reaction (ORR), is synthesized by a facile and low-cost hydrothermal treatment for the first time. Specifically, as a nitrogen-rich bridge-molecule, urea can trap free citric acid on planar planes, edges, and wrinkle sections of GO through amidation reaction in the initial stage. Then, polymer-like intermediates are in situ formed and carbonized to N- C dots on GO. Owing to the simultaneous N-doping into both C dots and GO characterized by XPS, as well as the formation of defective graphitic structures analyzed by Raman spectra, the as-prepared hybrid displays a remarkable electrocatalytic performance with more positive onset potential (0.13 V vs. Ag/AgCl) and high kinetic current density (up to 18.4 mA cm −2 at −0.70 V) comparable to commercial Pt/C catalyst. Furthermore, it demonstrates significantly higher catalytic efficiency (nearly 100% of four-electron ORR pathway) than those of N- C dots or N- C dots/GO mixture with an outstanding cyclic stability and superior methanol tolerance capability in alkaline solution. [ABSTRACT FROM AUTHOR]