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In situ probing of electron transfer at the dynamic MoS_(2)/graphene–water interface for modulating boundary slip

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Nano Research 2024年第8期17卷 7513-7521页

作者： Yishu Han Dameng Liu State Key laboratory of tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

The boundary slip condition is pivotal for nanoscale fluid *** research has primarily focused on simulating the interaction mechanism between the electronic structure of two-dimensional materials and slip of water at the nanoscale,raising the possibility for ultralow friction flow of water at the ***,experimentally elucidating electronic interactions at the dynamic solid–liquid interface to control boundary slip poses a significant *** this study,the crucial role of electron structures at the dynamic solid–liquid interface in regulating slip length was ***,the slip length of water on the molybdenum disulfide/graphene(MoS_(2)/G)heterostructure(100.9±3.6 nm)significantly exceeded that of either graphene(27.7±2.2 nm)or MoS_(2)(5.7±3.1 nm)*** was also analyzed how electron transfer significantly affected interface *** electrons played a crucial role in determining the type and proportion of excitons at both MoS_(2)–water and MoS_(2)/G–water ***,by applying voltage,distinct photoluminescence(PL)responses at static and dynamic interfaces were discovered,achieving a 5-fold modulation in PL intensity and a 2-fold modulation in the trion to exciton intensity *** electrons transfer from the top graphene to the bottom MoS_(2)at the MoS_(2)/G–water interface,reducing surface charge ***,the reduction of electrostatic interactions between the solid and water leads to an increased slip length of water on the MoS_(2)/G *** process aids in comprehending the origin of frictional resistance at the subatomic *** work establishes a foundation for actively controlling and designing of fluid transport at the nanoscale.

关键词： two-dimensional materials solid-liquid interface photoluminescence excitons electron transfer slip length

Comparative analysis of frictional behavior and mechanism of molybdenum ditelluride with different structures

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Friction 2024年第1期12卷 110-119页

作者： Lina ZHANG Xinfeng TAN Jianguo JIAO Dan GUO Jianbin LUO State Key laboratory of tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have layered structures with excellent tribological *** the energy difference between hexagonal-molybdenum ditelluride(2H-MoTe_(2))and distorted octahedral-molybdenum ditelluride(1T′-MoTe_(2))is very small among the transition metal dichalcogenides(TMDCs),MoTe_(2) becomes one of the most promising candidates for phase *** our experiment,we found that the friction force and friction coefficient(COF)of 2H-MoTe_(2) were an order of magnitude smaller than those of 1T′-MoTe_(2) by the atomic force microscope(AFM)*** friction difference between 1T′-MoTe_(2) and 2H-MoTe_(2) was further verified in molecular dynamics(MD)*** density functional theory(DFT)calculations suggest that the friction contrast is related to the difference in sliding energy barrier of the potential energy surface(PES)for a tip sliding across the *** PES obtained from the DFT calculation indicates that the maximum energy barrier and the minimum energy path(MEP)energy barrier of 2H-MoTe_(2) are both smaller than those of 1T′-MoTe_(2),which means that less energy needs to be dissipated during the sliding *** difference in energy barrier of the PES could be ascribed to its larger interlayer spacing and weaker Mo–Te interatomic interactions within the layers of 2H-MoTe_(2) than those of 1T′-MoTe_(2).The obvious friction difference between 1T′-MoTe_(2) and 2H-MoTe_(2) not only provides a new non-destructive means to detect the phase transition by the AFM,but also provides a possibility to tune friction by controlling the phase transition,which has the potential to be applied in extreme environments such as space lubrication.

关键词： friction two-dimensional(2D)materials distorted octahedral-molybdenum ditelluride(1T′-MoTe_(2)) hexagonal-molybdenum ditelluride(2H-MoTe_(2)) phase transition

In memoriam:Shizhu Wen(1932-2023)

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Friction 2024年第7期12卷 1341-1346页

作者： Jianbin LUO Yonggang MENG Yu TIAN State Key laboratory of tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Professor Shizhu Wen,the winner of the 2015 tribology Gold Medal,passed away due to illness on November 3,2023,at the age of *** was a professor of tsinghua university,an academician of the Chinese Academy of Sciences,and the Honorary President of the Chinese tribology Institute(CTI)from 1997 to *** Wen was born in 1932 in Jiangxi Province of China and graduated from tsinghua university in 1955,where he was awarded the Outstanding Graduate Gold Medal and then remained as an assistant professor at the *** Wen was promoted to full professor in *** had undertaken tribology research at the Imperial College London in 1979 and *** 1985,he presided over the establishment of the State Key laboratory of tribology(SKLT)of tsinghua university and served as the first director of the SKLT.

关键词： sided professor zhu

Prediction of ball-on-plate friction and wear by ANN with data-driven optimization

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Friction 2024年第6期12卷 1235-1249页

作者： Alexander KOVALEV Yu TIAN Yonggang MENG State Key laboratory of tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

For training artificial neural network(ANN),big data either generated by machine or measured from experiments are used as input to"learn"the unspecified functions defining the *** experimental data are fed directly into the optimizer allowing training to be performed according to a predefined loss *** predict sliding friction and wear at mixed lubrication conditions,in this study a specific ANN structure was so designed that deep learning algorithms and data-driven optimization models can be *** ball-on-plate friction and wear data were analyzed using the specific training procedure to optimize the weights and biases incorporated into the neural layers of the ANN,and only two independent experimental data sets were used during the ANN optimization *** the training procedure,the ANN is capable to predict the contact and hydrodynamic pressure by adapting the output data according to the tribological condition implemented in the optimization algorithm.

关键词： machine learning deep learning artificial neural network mixed lubrication

Hydration lubrication modulated by water structure at TiO2–aqueous interfaces

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Friction 2024年第4期12卷 591-605页

作者： Pingsu MA Yuan LIU Ke HAN Yu TIAN Liran MA State Key laboratory of tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The nature of solid-liquid interfaces is of great significance in *** advances have been made in lubrication based on hydration ***,a detailed molecular-level understanding is still ***,we investigated water molecule behaviors at the TiO2-aqueous interfaces by the sum-frequency generation vibrational spectroscopy(SFG-VS)and atomic force microscope(AFM)to elucidate the fundamental role of solid-liquid interfaces in *** contributions of water structures and hydration effects were revealed,where water structures played the dominant role in lubrication for TiO2 surfaces of varying hydrophilicity,while hydration effects dominated with the increasing of ion *** lubrication is observed on the initial TiO2 surfaces with strongly H-bonded water molecules compared to the hydrophilic TiO2 surfaces with more disordered *** stable ordered water arrangement with strong hydrogen bonds and the shear plane occurring between the ordered water layer and subsequent water layer may play a significant role in achieving lower *** adsorbed hydrated molecules with the increasing ionic concentration perturb ordered water but lead to the enhancement of hydration effects,which is the main reason for the improved lubrication for both *** work provides more insights into the detailed molecular-level understanding of the mechanism of hydration lubrication.

关键词： hydration lubrication interfacial water structures hydration effects titanium dioxide(TiO2)

A review of ultrafast laser micro/nano fabrication:Material processing,surface/interface controlling,and devices fabrication

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Nano Research 2024年第7期17卷 6212-6230页

作者： Heng Guo Jiawang Xie Guangzhi He Dezhi Zhu Ming Qiao Jianfeng Yan Jiachen Yu Jiaqun Li Yuzhi Zhao Ma Luo Haoze Han State Key laboratory of tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

Ultrafast laser processing technology has offered a wide range of opportunities in micro/nano fabrication and other fields such as nanotechnology,biotechnology,energy science,and photonics due to its controllable processing precision,diverse processing capabilities,and broad material *** processing abilities and applications of the ultrafast laser still need more *** the field of material processing,controlling the atomic scale structure in nanomaterials is *** effects exist in ultrafast laser surface/interface processing,making it difficult to modulate the nanostructure and properties of the surface/interface as *** the ultrafast laser fabrication of micro functional devices,the processing ability needs to be ***,we review the research progress of ultrafast laser micro/nano fabrication in the areas of material processing,surface/interface controlling,and micro functional devices *** useful ultrafast laser processing methods and applications in these areas are *** various processing effects and abilities,the ultrafast laser processing technology has demonstrated application values in multiple fields from science to industry.

关键词： ultrafast laser micro/nano fabrication material processing surface/interface controlling devices fabrication

Ultrafast laser processing of camouflaged metals by topography inherited multistep removal for information encryption

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Nano Research 2024年第8期17卷 7242-7249页

作者： Guangzhi He Jianfeng Yan Jiawang Xie Ming Qiao Ma Luo Yuzhi Zhao Haoze Han State Key laboratory of tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

Surfaces with micro-nanoscale structures show different optical responses,including infrared reflection,thermal radiation,and protective *** realization of structure camouflage is important for material ***,external cloaks or coatings are necessary in structure camouflage,which limits the surface ***,we propose a novel strategy for the direct structure camouflage through topography inherited removal(TIR)with ultrafast laser,featuring pristine topography preservation and scattering surface *** multistep TIR,pristine topographies are partially and uniformly removed to preserve the original designed *** response changes show the suppression of specular reflection by uniformizing reflected light intensity to a low level on the inherited *** produce various structure camouflages on large scaled substrates,and demonstrate applications of information encryption in code extraction and word recognition through structure *** proposed strategy opens opportunities for infrared camouflage and other technologies,such as thermal management,device security,and information encryption.

关键词： topography inherited removal ultrafast laser structure camouflage optical response information encryption

Low friction under ultrahigh contact pressure enabled by self-assembled fluorinated azobenzene layers

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Friction 2024年第7期12卷 1434-1448页

作者： Dandan XUE Zhi XU Linyuan GUO Wendi LUO Liran MA Yu TIAN Ming MA Qingdao ZENG Ke DENG Wenjing ZHANG Yichun XIA Shizhu WEN Jianbin LUO State Key laboratory of tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China national Center for Nanoscience and Technology Beijing 100190China

Extensive efforts have been made to pursue a low-friction state with promising applications in many fields,such as mechanical and biomedical *** which,the load capacity of the low-friction state has been considered to be crucial for industrial ***,we report a low friction under ultrahigh contact pressure by building a novel self-assembled fluorinated azobenzene layer on an atomically smooth highly-oriented pyrolytic graphite(HOPG)*** friction coefficients could be as low as 0.0005 or even lower under a contact pressure of up to 4 *** demonstrates that the low friction under ultrahigh contact pressure is attributed to molecular *** fluorination leads to effective and robust lubrication between the tip and the self-assembled layer and enhances tighter rigidity which can reduce the stress concentration in the substrate,which was verified by density functional theory(DFT)and molecular dynamics(MD)*** work provides a new approach to avoid the failure of ultralow friction coefficient under relatively high contact pressure,which has promising potential application value in the future.

关键词： ultrahigh contact pressure self-assembled layer fluorination robust lubrication

Interfacial tribochemical kinetics: A new perspective on superlubricity of diamond-like carbon films

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Science China(Technological Sciences) 2024年第7期67卷 2050-2052页

作者： CHEN WeiQi MA Tian-Bao State Key laboratory of tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

Friction is considered one of the primary challenges affecting the performance of machine operations and is a significant source of energy loss in industrial applications. About 30%of disposable energy is consumed by ... 详细信息

关键词： kinetics friction operations