Modification of graphene‐oxide surface in nitrogen and argon glow discharge plasma

Abstract

We performed glow discharge N2 or Ar plasma treatments of thin layers of graphene oxide (GO) deposited from slurry in alcohol onto stainless steel substrates. The treatment was performed in the preparation chamber of the x‐ray photoelectron spectrometer, allowing reliable in situ characterization of the treated surface by quantitative x‐ray photoelectron spectroscopy. For the treatment, 10 min plasma exposure was selected, based on preliminary experiments. Intensity of the treatment was enhanced by applying a negative bias between 0–300 V on the sample. Approximately 10 at% nitrogen was incorporated into the graphene oxide samples from N2 plasma within this short reaction time. When increasing the bias, the N‐content increased from 10 to 13 at%, together with the decrease of the O content from the starting value of 29 to ~15 at%. The reducing effect of Ar plasma was less pronounced, decreasing the oxygen content to ~21 at% only. The high resolution C1s, O1s, and N1s spectra show several different chemical states. The peak envelopes of the O1s and N1s lines could be decomposed to three while the C1s spectrum to five different peaks of identical position for all samples. The component peaks were tentatively assigned to specific chemical bonding states. The relative amounts of C–O and C–N bonding states changed slightly with advancement of the treatment performed at increasing biases. It was established that the carboxyl‐type and the carbonyl‐type C–O clusters were more affected by both plasma treatments as their amount was selectively eliminated. Copyright © 2016 John Wiley & Sons, Ltd.