The Role of Oxidative Debris on Graphene Oxide Films

Abstract

We study the effect of oxidative impurities on the properties of graphene oxide and on the graphene oxide Langmuir-Blodgett films (LB). The starting material was grupo Antolín nanofibers (GANF) and the oxidation process was a modified Hummers method to obtain highly oxidized graphene oxide. The purification procedure reported in this work eliminated oxidative impurities decreasing the thickness of the nanoplatelets. The purified material thus obtained presents an oxidation degree similar to that achieved by chemical reduction of the graphite oxide. The purified and non-purified graphene oxides were deposited onto silicon by means of a Langmuir-Blodgett (LB) methodology. The morphology of the LB films was analyzed by field emission scanning microscopy (FE-SEM) and micro-Raman spectroscopy. Our results show that the LB films built by transferring Langmuir monolayers at the liquid-expanded state of the purified material are constituted by close-packed and non-overlapped nanoplatelets. The isotherms of the Langmuir monolayer precursor of the LB films were interpreted according to the Volmer's model.

The effect of graphene oxide and its oxidized debris on the cure chemistry and interphase structure of epoxy nanocomposites

“…However, the oxidation peaks are considerably smaller compared to those of aGO which indicates that the quantity of oxygen moieties in aGO decreases after the removal of OD. In comparison, a similar reduction of degree of oxidative functionality was reported for bwGO [7,48,49]. Rourke et al, found that O/C ratio reduced from 0.5 in aGO to 0.25 in bwGO [7].…”

Effective bioelectrocatalysis of bilirubin oxidase on electrochemically reduced graphene oxide

“…It should be noted that this separation technique most likely did not remove "oxidation debris" from GO flakes [54,55] as can be deduced from UV-VIS spectra (data not shown). The adsorption peak at 234 nm detected in both samples, in good agreement with peak maximum for GO [55,56], suggests no substantial change in chemical composition of GO-S2 compared to GO. The biocathode GCE||Er(GO-S2 + BOD "in-situ") provided 2.7-fold higher current j = (120 ± 19) μA cm − 2 compared to the biocathode based on as-received GO flakes (Fig.…”

Graphene Oxide Thin Films: Influence of Chemical Structure and Deposition Methodology

“…However, since solid coverage and sheet wrinkles can be influenced by nanoplatelet size 31 and electric charge, 53 ζ potential and nanoplatelet size were previously determined. In a previous work, 14 ζ potential values of NGO and PNGO aqueous solutions were determined and they showed a bimodal distribution for NGO, centered at −34 and −50 mV, and a broad distribution centered at −20 mV for PNGO. In the current work, the ζ potential values obtained for GO and PGO, shown in Figure 1c, present a similar trend: a bimodal distribution centered at −42 and −65 mV for the nonpurified sample, GO, and a broad distribution centered at −34 mV for PGO, although the electric charge of graphene oxide synthesized from graphite is higher than that of sheets obtained from GANF.…”

“…22,24 These fragments are strongly adsorbed on the graphitic sheets through π−π stacking interactions 8,25 and can be removed by alkaline washing of GO. The purified material contains a lower amount of Ogroups than nonpurified ones 14,22,24,26 and presents a similar oxidation degree to that achieved by chemical reduction of GO. 14 According to this information, the structure of purified graphene oxide is quite different from the nonpurified one.…”

“…The purified material contains a lower amount of Ogroups than nonpurified ones 14,22,24,26 and presents a similar oxidation degree to that achieved by chemical reduction of GO. 14 According to this information, the structure of purified graphene oxide is quite different from the nonpurified one. However, although the presence of OD represents a clear disadvantage when applications demand chemical purity of graphene materials, it can play an important role in anchoring nanoparticles or polymers 27,28 to the GO sheets across the carboxylic or epoxy and hydroxyl groups.…”