Water Protects Graphitic Surface from Airborne Hydrocarbon Contamination

Abstract

The intrinsic wettability of graphitic materials, such as graphene and graphite, can be readily obscured by airborne hydrocarbon within 5-20 min of ambient air exposure. We report a convenient method to effectively preserve a freshly prepared graphitic surface simply through a water treatment technique. This approach significantly inhibits the hydrocarbon adsorption rate by a factor of ca. 20×, thus maintaining the intrinsic wetting behavior for many hours upon air exposure. Follow-up characterization shows that a nanometer-thick ice-like water forms on the graphitic surface, which remains stabilized at room temperature for at least 2-3 h and thus significantly decreases the adsorption of airborne hydrocarbon on the graphitic surface. This method has potential implications in minimizing hydrocarbon contamination during manufacturing, characterization, processing, and storage of graphene/graphite-based devices. As an example, we show that a water-treated graphite electrode maintains a high level of electrochemical activity in air for up to 1 day.

Electrowetting on conductors: anatomy of the phenomenon

“…These findings are consistent with other surface sensitive measurements on basal plane HOPG, for example, the effect of ambient exposure on its contact angle at neutrality, 23 and our own recent work, which has…”

“…[21][22][23] The presence of the latter is also reported to affect the intrinsic electrochemical response of graphite surfaces, either through the effect on the kinetics of heterogeneous electron transfer, [23][24][25][26] or on the capacitance of graphite/electrolyte interfaces. 27 Here we describe the effect of surface treatment, including ambient ageing, on the graphite electrowetting response and also attempt to generalise the phenomenon to other carbonaceous surfaces including graphene, with the aim of better understanding the specific electrode-electrolyte surface interactions responsible for the reversible wetting process.…”

Understanding the intrinsic water wettability of graphite

“…[49][50][51][52][53][54][55] Moreover, they showed that electron transfer rates significantly deteriorate when the graphitic surface is exposed to air; 50 this has been corroborated through work by Velický and Dryfe et al, [56][57][58] Nioradze and Amemiya et al, [59][60][61] and Li and Liu et al 62 These results have salient implications for graphene and graphite electrodes and batteries. Taking into account a thin hydrocarbon layer, or controlling to restrict hydrocarbon adsorption, can substantially improve device performance.…”

“…It is important to note that all experiments conducted by myself and my co-workers were taken on samples that were purchased new and once the sample got substantially thin it was replaced and no longer used for experiments. 62,70,[75][76][77] ZYA is the highest quality of HOPG and exfoliates nearly perfectly. Visually, there were no flakes or exfoliation-induced defects noticeable and all experimental testing was performed only on the visually pristine basal surface.…”

Suppression of intrinsic roughness in encapsulated graphene

“…Typical cleaning procedures result in clean graphene patches of only nanometer dimensions [25][26][27][28]. Polymethyl methacrylate (PMMA) is often used as an intermediate supporting polymer during 2D materials transfer; however, PMMA residues in particular have proven to be challenging to remove by typical cleaning procedures such as thermal annealing in Ar/H 2 [23], and until now prevention strategies have proven to be the most effective cure [29].…”