Rapid Synthesis Of Nitrogen Doped Graphene By Microwave Heating For Oxygen Reduction Reactions In Alkaline Electrolyte

The high cost of catalysts limits the commercializing of fuel cells, although the Pt-based catalysts show a good electrochemical activity, the high cost, scarce source, have highly precluded the large-scale commercial application of fuel cells. Recent efforts in replacing Pt led to the development of various non-precious electrocatalysts of oxygen reduction reaction (ORR), in which nitrogen doped graphene have been widely reported. Nevertheless, the N-doping methods reported are generally time-consuming, leading to low productive efficiency. The doping method of high efficiency, low cost should be much further explored.Since graphene is a microwave absorption material, nitrogen doped graphene can be prepared by the microwae heating graphene under NH3atmosphere, N atoms can replace C atoms of graphene network. It is reported that graphite N play a key role to ORR activity in alkaline solution. To explore how to get more graphite and better ORR activity, we conducted the following study.(1) To prepare nitrogen doped graphene by microwave heating graphene under NH3atmosphere repeatedly. According to the analysis of Elemental analysis, XPS and ORR for nitrogen doped graphene which is obtained with different microwave heating times, the graphite N plays a key role to ORR in alkaline solution, the ORR activity increases with microwave heating times and gets saturated when microwave heating for4times.(2) To prepare nitrogen doped graphene by microwave heating graphene with different time (2s,5s,10s,30s) under NH3atmosphere. We also use tube furnace to heat up the graphene to get nitrogen doped graphene under different temperature (300℃,500℃,700℃). The results of Elemental analysis, XPS and ORR show that the ORR activity in alkaline electrolyte increases with microwave heating time, and get saturated after only10s of microwave heating, and the ORR activity of the nitrogen doped graphene prepared with tube furnace is similar with that of the nitrogen doped graphene prepared by microwave heating. It suggests that the microwave heating graphene is a rapid and efficient method for nitrogen doping.