Fluorination to enhance superlubricity performance between self-assembled monolayer and graphite in water

Li, Jianfeng; Cao, Wu; Ma, Ming

doi:10.1016/j.jcis.2021.03.133

Cited by 19 publications

(14 citation statements)

References 52 publications

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“…When removing the TRT through the hot-pressing procedure, the wrinkled and compress-strained graphene could be further flattened by the lateral component force that drives the graphene slipping on the FSAM surface. Also, the F-terminated structure can create a reduced friction coefficient (from 0.16 to 0.0003) surface, 37 resulting in a wrinkle-free graphene film. By contrast, in the WT graphene/FSAM/SiO 2 sample, the water residue remains between the graphene and FSAM layer due to the hydrophobicity, leading to trapping water residues inside the graphene film as tiny liquid cells.…”

Section: Resultsmentioning

confidence: 99%

Wrinkle-Free Graphene Films on Fluorinated Self-Assembled Monolayer-Modified Substrates for Enhancing the Electrical Performance of Transistors

Lin

Shen

et al. 2022

ACS Appl. Nano Mater.

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Self-assembled monolayer (SAM)-functionalized substrates are widely used for tailoring the electronic properties (i.e., p- and n-type doping) of two-dimensional materials, which might suppress the charge scattering, impurities, and wrinkles that can severely decline electrical properties. The fluorinated self-assembled monolayer (FSAM) is also used for promoting electrical properties by eliminating the small number of water molecules/residues between the substrate and graphene during the typical wet transfer process. However, taking graphene as an example, most of the graphene/SAM or graphene/FSAM studies are focused on the enhancement of their electrical properties and lack investigation on their surface morphology after transfer and the correlation between them. Herein, a strategy is discovered in which FSAM-modified substrates help construct a wrinkle-free graphene film with the dry transfer process due to the low surface energy between the graphene and FSAM. Trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS) was selected as a precursor toward the formation of the monolayer and highly uniform FSAM using a facile dip-coating route, which is feasible on versatile substrates such as Si, SiO2/Si, and poly(ethylene terephthalate) (PET). The surface roughness of the FSAM-modified SiO2 substrate reduces from 2.98 to 0.13 nm. Therefore, the lower surface energy (from 60.80 to 8.12 mN/m) was found to enhance the carrier mobility of the transferred graphene by about 1.77 times, increasing from 894.6 to 1588 cm2/(V·s). Furthermore, a top-gated field-effect transistor based on graphene/FSAM was fabricated and characterized in which the FSAM decouples from the strong substrate interference and significantly improved the field-effect mobility by up to 17 times compared to that of graphene without substrate modification. Thus, this work provides a facile strategy to avoid wrinkle defects and suppress charge scattering through the decoupling from the substrate, which could be applied to other two-dimensional (2D) materials for improving their electrical performance on transistors and flexible electronics.

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Section: Resultsmentioning

confidence: 99%

Wrinkle-Free Graphene Films on Fluorinated Self-Assembled Monolayer-Modified Substrates for Enhancing the Electrical Performance of Transistors

Lin

Shen

et al. 2022

ACS Appl. Nano Mater.

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“…The frictional forces between the probe and sample under different environments were measured with AFM using lateral force mode by driving the probe to slide against the sample surface with a scanning area of 0.5 μm × 0.5 μm (256 × 256 lines), which was calculated from the half-width of a complete force loop and the lateral sensitivity of the probe obtained by the improved wedge calibration method. 47,48 Characterization. The layered structure of BP nanoflakes was observed by HRTEM (JEM-2100F, JEOL).…”

Section: Methodsmentioning

confidence: 99%

Alkene-Catalyzed Rapid Layer-by-Layer Thinning of Black Phosphorus for Precise Nanomanufacturing

Wang

et al. 2022

ACS Nano

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Black phosphorus (BP) is a promising material for electronic and optoelectronic applications. However, it is still challenging to obtain geometrically well-defined BP with desirable thickness. The method involving rapid BP surface reaction via alkene-catalyzed oxidation and easy removal of reactants by a mechanical effect was proposed to achieve the precise layer-by-layer thinning and real-time thickness monitoring of BP for nanopatterning with high spatial resolution based on mechanical scanning probe nanolithography. The enhanced electron affinity of oxygen with the assistance of a carbon–carbon double bond (CC) in the alkene was demonstrated by density functional theory calculations, shortening the BP surface oxidation period by 99%, which provides access for the rapid thinning. The few-layer BP nanoflake with nested structure and arbitrary thickness on various substrates and the nanopatterned heterojunctions (BP/graphene and BP/hexagonal boron nitride) can be precisely fabricated by the adjustment of scanning number under a small load. This thinning technology was efficient and universal, which could be used to fabricate a BP field-effect transistor with a thinned channel to enhance the capability for current modulation, showing great potential applications for designing high-performance nanodevices.

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“…Before the measurements, the sensitivities of the AFM tip in the oil and air environments were calibrated, and then the calibrated values were applied to the measurement in the same environment. The vertical sensitivities of the tip were 0.013 nN/mV in the oil environment and 0.022 nN/mV in the air environment, and the lateral sensitivities of the tip were 1.2 nN/mV in the oil environment and 1.9 nN/mV in the air environment, which were calibrated by the improved wedge method. , Normal force interactions between the tip and oxidized BP were measured by making the tip gradually approach the oxidized BP surface and then move away from it. The frictional forces were measured by sliding the tip against oxidized BP with a scanning area of 500 nm × 500 nm, whose value can be acquired by determining the half-width of the lateral force loop at each cycle (take the average value of eight friction loops with the same load) and the lateral sensitivity of the tip.…”

Section: Methodsmentioning

confidence: 99%

“…In the nonanoic acid environment, when the contact force was low (7 nN, less than F cr ), there was no jump- into-contact phenomenon because of the disappearance of the attractive force during the approach process, and meanwhile, the adhesive force also vanished during the retrace process (Figure 3c), which was a representative characteristic of the existence of a confined molecular layer in the contact zone separating the tip from oxidized BP. 25,31 Nevertheless, as the contact force was high (18 nN, greater than F cr ), during the approach process a clear repulsive force that originated from the confined nonanoic acid layer was observed, but when the contact force reached 12 nN, the repulsive force would collapse, resulting in the jump-into-contact phenomenon. After that, the apparent adhesive force was also observed during the retrace process, providing evidence that the confined molecular layer formed by nonanoic acid had been squeezed out under high load leading to the direct contact between the tip and oxidized BP.…”

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confidence: 99%

Synergistic Lubrication Effect between Oxidized Black Phosphorus and Oil Molecules Triggers Superlubricity

2022

J. Phys. Chem. Lett.

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Oxidized black phosphorus (BP) has been demonstrated as a promising oil-based nanoadditive because of its superior friction-reducing capability. However, the synergistic lubrication effect between oxidized BP and oil at the molecular level dominating the friction properties remains unclear. In this Letter, the synergistic lubrication effect between oxidized BP and two typical oil molecules (nonane and nonanoic acid) was explored with an atomic force microscope. The superlubricity of oxidized BP with an ultralow friction coefficient of 0.006 was achieved in the nonanoic acid environment, exhibiting a 96% reduction compared with that in the nonane environment. There was a confined nonanoic acid layer in the contact zone with a tilt angle of 35°because of the hydrogen bonding interaction, contributing to the superlubricity. This observation sheds light on the exploration of the lubrication mechanism of oxidized BP as a nanoadditive in oil, which reveals the considerable implications for the design of highperformance lubrication system.

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Fluorination to enhance superlubricity performance between self-assembled monolayer and graphite in water

Cited by 19 publications

References 52 publications

Wrinkle-Free Graphene Films on Fluorinated Self-Assembled Monolayer-Modified Substrates for Enhancing the Electrical Performance of Transistors

Wrinkle-Free Graphene Films on Fluorinated Self-Assembled Monolayer-Modified Substrates for Enhancing the Electrical Performance of Transistors

Alkene-Catalyzed Rapid Layer-by-Layer Thinning of Black Phosphorus for Precise Nanomanufacturing

Synergistic Lubrication Effect between Oxidized Black Phosphorus and Oil Molecules Triggers Superlubricity

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