On the wettability transparency of graphene-coated silicon surfaces

Abstract

In order to better understand the behavior and governing characteristics of the wetting transparency phenomenon observed in graphene-coated surfaces, molecular dynamics simulations were coupled with a theoretical model. Graphene-coated silicon was selected for this analysis, due to potential applications of hybrid silicon-graphene materials as detectors in aqueous environments. The results indicate good agreement between the theory and simulations at the macroscopic conditions required to observe wetting transparency. A microscopic analysis was also conducted in order to identify the parameters, such as the interaction potential energy landscape and the interfacial liquid structure that govern the wetting behavior of graphene-coated surfaces. The interfacial liquid structure was found to be different between uncoated Si(100) and the graphene-coated version and very similar between uncoated Si(111) and the graphene-coated version. However, the concentration of liquid particles for both silicon surfaces was found to be very similar under transparent wetting conditions.

Substrate Effects in Graphene‐Based Electric Double‐Layer Capacitors: The Pivotal Interplays between Ions and Solvents

“…According to the theoretical work, the predicted adsorption energy of liquid on Cu supports varied marginally with the insertion of graphene layer, highlighting the overwhelming role of background substrates in determining the interfacial wettability . Noteworthy, compared with previous observations of completely wetting transparency using pure water solutions, a merely partial transparency of graphene was achieved in this work ,,. Such finding was presumably affiliated with the presence of electrolyte ions, where a moderate increment of contact angle was expected upon addition of salts …”

“…On the other hand, there has been a dramatic proliferation of ongoing studies concerning with the interfacial properties of graphene triggered by background supports, which is considered to impose great impacts on the electrolyte structuring, and thereby the charge storage capability of EDLCs . Wehling et al.…”

Wettability transparency and the quasiuniversal relationship between hydrodynamic slip and contact angle

“…1 indicate that the theoretical model reported in Ref. 32 is sufficiently accurate to predict the wettability of graphene-coated silicon. Two different values for the equilibrium separation between graphene and silicon (d GS ) were considered, since this parameter is the only unknown in the theoretical model of wettability.…”

“…Two different values for the equilibrium separation between graphene and silicon (d GS ) were considered, since this parameter is the only unknown in the theoretical model of wettability. 32 Some authors have reported values of d GS ¼ 3.55 Å , a value obtained through mixing rule approximations of the interaction potentials, 33 while recent experiments 34,35 and simulations 36 suggest that d GS % 2:0Å. Hence, d GS ¼ 2.0 Å was adopted for the remaining of this investigation.…”

“…2(b) indicates that L s is different for hydrophobic silicon nanochannels (h > 100 ) because the depletion length is more prominent in Si(111) than Si(100) surfaces. 32 Additionally, the reason that the graphene-coated slip is similar to the hydrophobic Si(111) can be explained by recognizing that both surfaces exhibit similar d values. Thus, Fig.…”