Preparation and electrochemical characterization of nitrogen doped graphene by microwave as supporting materials for fuel cell catalysts

A quick and efficient approach to prepare nitrogen doped graphene (NG) is proposed in this paper via microwave heating in NH3 atmosphere. Results show that graphene, as an allotrope of carbon, is a good microwave-absorbing material and can reach a high temperature in minutes, facilitating nitrogen incorporation into the structure under NH3. Elemental analysis and X-ray photoelectron spectroscope (XPS) verified the success of N-doping with the nitrogen content of 5.04 wt%. For comparison, both plain grapheme (G) and the NG were used as supporting materials for platinum to investigate their potential application in fuel cells. Transmission electron microscope (TEM) images showed that the NG improved the distribution of Pt particles. Themogravimetry (TG) and differential scanning calorimeters (DSC) revealed better thermal stability of the Pt/NG than that of the Pt/G. Furthermore, the Pt/NG catalysts exhibited higher electrochemical active surface area, methanol catalytic activity, and tolerance to CO poisoning than those of the Pt/G under fuel cell conditions. It suggests that the NG prepared by microwave synthesis has provided a new way to improve electrocatalytic activity in fuel cells.

► N-doped graphene was firstly prepared by microwave of graphene in NH3 atmosphere with the high nitrogen content.
► The N-doping process was very fast. Graphene can absorb microwave easily and reach a very high temperature in few seconds, quickly incorporating nitrogen atoms into graphene.
► TEM images showed that N-doped graphene was in favor of improving the dispersion of Pt particles.
► Thermogravimetry analysis showed that the thermal stability of Pt/NG was better than Pt/G due to the enhancement of interaction between Pt and graphene and the decrease of defects on graphene sheets.
► Pt/NG catalysts exhibited higher electrochemical active surface area, higher methanol catalytic activity, better tolerance to CO poisoning and better long term operation stability than Pt/G catalysts.