Deep-Eutectic Solvents Derived Nitrogen-Doped Graphitic Carbon as a Superior Electrocatalyst for Oxygen Reduction.

The activity and stability of electrocatalyst for oxygen reduction reaction (ORR) essentially depends on its structural and compositional properties. Herein, we report the facile preparation of nitrogen-doped graphitic carbon (NGC) via the pyrolysis of deep-eutectic solvents (DESs) as a superior electrocatalyst for ORR. The resulting NGCs possess high surface areas, rich nitrogen content, and favorable graphitization degree, all of which are highly desired for the ORR catalysts. The effects of the pyrolysis temperature on the ORR performance of the final products are explored. The results implied that the material fabricated at 900 °C (NGC900) is identified as the best ORR catalyst in the series of samples. Specifically, NGC900 shows efficient performance toward ORR with an onset potential of 0.97 V and a half potential of 0.84 V, which bears comparison with the commercial Pt/C catalyst with enhanced stability in the alkaline media. The superior ORR performance of NGC900 may be ascribed to the balance between the surface area, pyridinic nitrogen, and defect of NGCs. The rational design of NGCs with an efficient ORR activity and stability based on the low-cost DESs implies adequate support for the development of energy devices in practical application.