Role of Interfacial Water in the Tribological Behavior of Graphene in an Electric Field

Lang, Haojie; Zou, Kun; Chen, Ruling; Huang, Yao; Peng, Yitian

doi:10.1021/acs.nanolett.2c00361

Cited by 15 publications

(10 citation statements)

References 51 publications

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“…Owing to its two-dimensional (2D) planar structure with strong in-plane covalent bonding, graphene has an ultrahigh mechanical strength and intrinsically low surface friction. − Moreover, it has been shown that the frictional properties of graphene can be actively altered by introducing topological defects, − chemical functionalization, − varying the supporting substrates, − changing the ambient conditions like humidity and temperature, − and the electronic method. − These unique characteristics render graphene a promising candidate as a versatile friction modifier with atomically thin thickness. Despite the high potential, the friction regulation methods for graphene are typically irreversible, which means that its frictional property is hard to be recovered once changed.…”

Section: Introductionmentioning

confidence: 99%

Revisiting Frictional Characteristics of Graphene: Effect of In-Plane Straining

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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Supreme mechanical performance and tribological properties render graphene a promising candidate as a surface friction modifier. Recently, it has been demonstrated that applying in-plane strain can effectively tune friction of suspended graphene in a reversible manner. However, since graphene is deposited on solid surfaces in most tribological applications, whether such operation will result in a similar modulation effect becomes a critical question to be answered. Herein, by depositing graphene onto a stretchable substrate, the frictional characteristics of supported graphene under a wide range of strain are examined with an in situ tensile loading platform. The experimental results show that friction of supported graphene decreases with increasing graphene strain, similar to the suspended system. However, depending on the adherence state of the graphene/substrate interface, the system exhibits two distinct friction regimes with significantly different strain dependences. Assisted by detailed atomic force microscopy imaging, we attribute the unique behavior to the transition between two friction modulation modes, i.e., contact-quality-dominated friction and puckering-dominated friction. This work provides a more comprehensive view of the influence of strain on surface friction of graphene, which is beneficial for active modulation of graphene friction through strain engineering.

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Section: Introductionmentioning

confidence: 99%

Revisiting Frictional Characteristics of Graphene: Effect of In-Plane Straining

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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“…The cross-section profile in Figure c verifies a thickness of ∼0.91 nm, which can be attributed to a GO monolayer. , The X-ray photoelectron spectroscopy (XPS) spectra in Figure e and Figure S2 indicate that the GO surface is terminated with hydrophilic groups, such as −OH and −COOH . These terminations are prone to adsorb water molecules from the atmosphere, − thus resulting in a slightly larger thickness compared to the measured lattice spacing of ∼0.78 nm. Based on these results, the atomic structure of a GO monolayer is schematically depicted in Figure f. − …”

Section: Resultsmentioning

confidence: 82%

Layer-Dependent Nanowear of Graphene Oxide

et al. 2023

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The mechanical performance and surface friction of graphene oxide (GO) were found to inversely depend on the number of layers. Here, we demonstrate the non-monotonic layer-dependence of the nanowear resistance of GO nanosheets deposited on a native silicon oxide substrate. As the thickness of GO increases from ∼0.9 nm to ∼14.5 nm, the nanowear resistance initially demonstrated a decreasing and then an increasing tendency with a critical number of layers of 4 (∼3.6 nm in thickness). This experimental tendency corresponds to a change of the underlying wear mode from the overall removal to progressive layer-by-layer removal. The phenomenon of overall removal disappeared as GO was deposited on an H-DLC substrate with a low surface energy, while the nanowear resistance of thicker GO layers was always higher. Combined with density functional theory calculations, the wear resistance of few-layer GO was found to correlate with the substrate's surface energy. This can be traced back to substrate-dependent adhesive strengths of GO, which correlated with the GO thickness originating from differences in the interfacial charge transfer. Our study proposes a strategy to improve the antiwear properties of 2D layered materials by tuning their own thickness and/or the interfacial interaction with the underlying substrate.

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“…The real part (ε′) (Equation S3, Supporting Information) and imaginary part (ε′′) (Equation S4, Supporting Information) of complex permittivity correspond to the storage and dissipation of electrical energy, respectively. [40][41][42][43] The lowest permittivity of CF and CNCs/CF at 600 °C annealing is due to the formation of carbon skeletons with poor conductivity at a lower carbonization temperature (Figures S8 and S9, Supporting Information). As the carbonization temperature increases, higher conductivity and permittivity are obtained.…”

Section: High-efficiency Ma Performancementioning

confidence: 99%

Carbon Nanocoils/Carbon Foam as the Dynamically Frequency‐Tunable Microwave Absorbers with an Ultrawide Tuning Range and Absorption Bandwidth

Shi

Wang

et al. 2022

Adv Funct Materials

122

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The absorption frequency of conventional microwave absorbing materials (MAMs) is hardly tuned in operando, while such dynamic frequency regulation of MAMs is of great significance to meet the high demands of modern radars and intelligent electron devices. Here, an ingenious frequency-tuning strategy by means of the pressure variations is developed by fabricating highly compressible carbon nanocoils/carbon foam (CNCs/CF) as a dynamically frequency-tunable microwave absorber. Through adjusting the compression strain, the absorption bandwidth of CNCs/CF can be precisely tuned from S-band (2−4 GHz) to Ku-band (12−18 GHz). The adjustable effective absorption bandwidth is as wide as 15.4 GHz, which covers 96% of the entire microwave frequency. Under 10% compression strain, CNCs/ CF shows an attractive bandwidth of 9.0 GHz and a strong reflection loss of −64.6 dB. Furthermore, the CNCs/CF also exhibit a good thermal insulation, strong hydrophobicity, and strain-sensitive conductivity, endowing them with fascinating functions of heat insulation and self-cleaning. The method of utilizing an external pressure to dynamically adjust the absorption frequencies of CNCs/CF is demonstrated for the first time, which opens an avenue for the applications of dynamically frequency-tunable MAMs with an ultrawide adjusting range and absorption bandwidth.

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Role of Interfacial Water in the Tribological Behavior of Graphene in an Electric Field

Cited by 15 publications

References 51 publications

Revisiting Frictional Characteristics of Graphene: Effect of In-Plane Straining

Revisiting Frictional Characteristics of Graphene: Effect of In-Plane Straining

Layer-Dependent Nanowear of Graphene Oxide

Carbon Nanocoils/Carbon Foam as the Dynamically Frequency‐Tunable Microwave Absorbers with an Ultrawide Tuning Range and Absorption Bandwidth

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