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Reduction and covalent modification of graphene‐oxide by nitrogen in glow discharge plasma
Author(s) -
Mohai M.,
László K.,
Bertóti I.
Publication year - 2018
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6411
Subject(s) - diazine , graphene , nitrogen , oxide , analytical chemistry (journal) , chemistry , x ray photoelectron spectroscopy , glow discharge , covalent bond , plasma , materials science , nanotechnology , organic chemistry , chemical engineering , physics , quantum mechanics , engineering
In this work, we performed plasma treatment of thin layers of graphene oxide samples in various nitrogen containing gases (mainly NH 3 and N 2 ). Experiments were performed in the preparation chamber of the X‐ray photoelectron spectrometer, allowing “in situ” characterization of the treated surface. Introduction of nitrogen into the top surface was intensified by applying negative voltage on the sample between 0 and 300 V accelerating the positive plasma ions towards the sample. Significant amount of nitrogen (≈10 atomic %) was built into the top atomic layers of the graphene oxide samples at application of the 2 types of plasma gases for 10‐minute reaction time. When comparing the NH 3 and N 2 plasma treatments, more complete reduction and closely similar amount of nitrogen was found at applying NH 3 plasma. When increasing the bias, the N‐content increased, together with decrease of the O content. The high‐resolution C1s, O1s, and N1s spectra are broad, representing different chemical states. The peak envelopes of the O1s and N1s lines could be decomposed essentially to 3, while the C1s spectrum to 5 different, well‐separated peaks, being identical for all samples. The component peaks were assigned to specific chemical bonding states (N1s: 398.3 eV sp 2 pyridine N, 399.7 eV sp 2 pyrrole, diazine or triazine N, 401.0 eV N in graphite plane; O1s: 530.8 eV carbonyl, 532.2 eV ether, epoxy, alcohol, ester C═O, 533.6 eV ester C―O―C, carboxyl OH). The relative amounts of C―O and C―N bonding states changed significantly with advancement of the treatment performed at increasing biases.