Synthesis And Electrochemical Catalytic Performance Of Nitrogen Doped Graphene Using CVD Method

The doping of graphene with heteroatom can introduce the band gap and surficial active sites for enhancing its reaction activity in the premise of keeping excellent electrical properties of graphene. The doped graphene can be conveniently applied into many fields such as electrochemistry, fuel cells, sensors, super capacitors. Among the various methods for preparing nitrogen doped graphene, chemical vapor deposition(CVD) has become one of the most used ways. As it has the advantages like simple structure, safety, environmental protection and no pollution. And controlling the reaction condition is easy to realize the controllable preparation of large area nitrogen doped graphene. Besides, the nitrogen doped graphene is easy to transfer, thus becoming the optimal method for mass production of large area, high quality of nitrogen doped graphene. A large number of studies show that, the nitrogen doping amount, nitrogen doped types, crystallinity, defect states directly affect the catalyst performance of oxygen reduction reaction. So, how to realize the control of these structural properties is the key factor and urgent matter in preparing high catalytic activity graphene.One of the research content of this paper is through controlling many reaction parameters of CVD growth process, such as carbon source, hydrogen flow rate, reaction temperature, reaction time and so on, to find the optimum preparation conditions, and to explore the various influencing factors on the graphene. After a series of experiments, we successfully prepared continuous and uniform single- and few-layer N-doped graphene. We found that the lowest temperature preparation of nitrogen doped graphene is 950 ℃, the flow of hydrogen, reaction time and the annealing treatment influence the crystallization quality of grapheneThen we selected 4 representative samples of nitrogen doped graphene to analyze the electrochemical performance after characterizing the structure of N-doped graphene with SEM, SAED, TEM, and XPS. It is indicated that the nitrogen doped graphene is single- and few- layer; the highest nitrogen amount is 8.94%, the lowest was 0.61%, the dominant N-doping types are pyridine, pyrrole and graphite. And we analyzed the electrochemical measurements using CV, LSV, and EIS, found combining with the XPS analysis that the oxygen reduction activity of the nitrogen doped types is: graphite > pyridine> pyrrole. And we also use the RDE tests to explore the electrical catalytic kinetics of nitrogen doped graphene.