Characteristics of nitrogen-doped carbon films grown by sputtering as potential cathode catalysts for oxygen reduction reaction

This work demonstrates the performance of carbon films doped with different contents of nitrogen as cathode catalysts of the oxygen reduction reaction (ORR). Nitrogen content was controlled directly by adjusting the Ar/N 2 ratio during the growth of a carbon film by radio frequency (RF) magnetron sputtering. The nitrogen content and C–N bonding configuration of the sample were characterized by X-ray photoelectron spectroscopy (XPS), which demonstrated that the content of pyridinic-type nitrogen increased with the increase in nitrogen content. The nitrogen-doped carbon film with the largest amount of pyridinic-type nitrogen configuration exhibits superior ORR activity, which leads to a four-electron transfer in alkaline solution, which opens the possibility of the application of metal-free catalysts.