title: Catalyst-free synthesis of nitrogen-doped graphene via thermal annealing graphite oxide with melamine and its excellent electrocatalysis.
abstract: The electronic and chemical properties of graphene can be modulated by chemical doping foreign atoms and functional moieties. The general approach to the synthesis of nitrogen-doped graphene (NG), such as chemical vapor deposition (CVD) performed in gas phases, requires transitional metal catalysts which could contaminate the resultant products and thus affect their properties. In this paper, we propose a facile, catalyst-free thermal annealing approach for large-scale synthesis of NG using low-cost industrial material melamine as the nitrogen source. This approach can completely avoid the contamination of transition metal catalysts, and thus the intrinsic catalytic performance of pure NGs can be investigated. Detailed X-ray photoelectron spectrum analysis of the resultant products shows that the atomic percentage of nitrogen in doped graphene samples can be adjusted up to 10.1%. Such a high doping level has not been reported previously. High-resolution N1s spectra reveal that the as-made NG mainly contains pyridine-like nitrogen atoms. Electrochemical characterizations clearly demonstrate excellent electrocatalytic activity of NG toward the oxygen reduction reaction (ORR) in alkaline electrolytes, which is independent of nitrogen doping level. The present catalyst-free approach opens up the possibility for the synthesis of NG in gram-scale for electronic devices and cathodic materials for fuel cells and biosensors.
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Zhen-Huan
authors.initials: ZH
authors.lastname: Sheng
authors.forename: Lin
authors.initials: L
authors.lastname: Shao
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Chen
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Bao
authors.forename: Feng-Bin
authors.initials: FB
authors.lastname: Wang
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Xia
mesh_terms: D015374:Biosensing Techniques; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry / Q000379:methods; D004573:Electrolytes; D006108:Graphite / Q000737:chemistry*; D006358:Hot Temperature; D018625:Microscopy, Atomic Force / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009584:Nitrogen / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D014227:Triazines / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D004573:Electrolytes; D010087:Oxides; D014227:Triazines; D002244:Carbon; D006108:Graphite; C011907:melamine; D009584:Nitrogen; D010100:Oxygen