Chinese Academy of Sciences acquires new results of van der Waals shear action between two layers of graphene

Micronanobubble mechanics experimental diagram

The related research results Measuring Interlayer Shear Stress in Bilayer Graphene was published in the Physical Review Letters [Phys. Rev. Lett. 119 (2017) 036101] and served as the current editor-in-chief. Recommended papers (Editors' Suggestion).

This work was also reported as the Focus Story in [Physics 10 (2017) 81] as "Graphene Sliding on Graphene". It is believed that this study was first measured by bubbling method. The graphene interlaminar shear force was obtained to obtain a graphene sheet providing the first measurement of the shear forces between graphene layers, an essential factor in many graphene-based devices. The research work was supported by the National Fundamental Research Program's major nano R&D program and the National Outstanding Youth Science Fund.

Two-dimensional materials exhibit a variety of excellent and novel features and have received extensive attention and research. In fact, due to the limitation of the preparation technology or the need of functional design, the two-dimensional materials of the single atomic layer are often stacked into a multi-layer structure, and the multi-layer graphene/polymer composite material and multi-layered sub-layer structure are two-dimensional. Material capacitors, multilayer two-dimensional material heterojunctions, etc. are common examples.

As a “surface interface” material, the van der Waals interaction between layers of multi-layered two-dimensional material layers is critical to the application of functional characteristics and service reliability. However, the current research is aware of the key parameters of the inter-layer deformation and interaction of two-dimensional materials. Very little.

The research team skillfully designed the micro-nano bubbling experimental method to control the swelling of single-layer/double-layer graphene by uniformly controlling the pressure difference inside and outside the micro- and nano-holes so as to achieve the “pulling” of the substrate outside the hole. The single-layer/double-layer graphene slips to the micropore center; in the double-layer graphene bubbling experiment, the interface between the graphene layers has a much greater effect than the interface between the lower graphene and the silica substrate. Weak shear resistance.

With Raman spectroscopy and atomic force microscopy, the inter-layer shear deformation field can be precisely measured and expanded as the pressure increases. Combined with experimental analysis, theoretical calculations and molecular dynamics simulations, a double layer graphene interlayer shear is obtained. The cut resistance is about 40 kilopascals; this is about 40 times lower than the shear resistance of single atomic layer graphene and silica substrates measured with the same experimental technique.

This work provides a novel and controllable experimental technique to characterize the van der Waals shear action between two-dimensional material layers, which in turn helps to understand the lubrication between two-dimensional material layers. It also provides new ideas for the strain engineering of two-dimensional materials. .

Horacio Espinosa, an expert in micro-nano mechanics at the Northwestern University, a member of the European Academy of Sciences and a member of the Russian Academy of Sciences, spoke highly of this study. “This study gives an exquisite and novel experimental technique to measure the interface between two-dimensional material layers and the substrate. Performance, research results will provide new opportunities for device and material design."

Roland Bennewitz, Professor of the Leibniz Institute of New Materials in Germany, believes that the study provides a quantitative experimental basis for understanding the superior lubricating properties of graphene and believes that “this research is the cornerstone of the study and the relevant atomic dimensions The simulation provided reliable experimental results, and then people can better understand the excellent lubricating effect of graphene."

The co-first author of the dissertation is Wang Guorui, a doctoral student at the China University of Science and Technology, and Dai Shihe, a graduate student of the Institute of Mechanics at the Chinese Academy of Sciences. The research work was done in collaboration with Tan Pingheng, a researcher at the Institute of Semiconductors of the Chinese Academy of Sciences, Wei Yueguang, a professor at Peking University, and Huang Rui, a professor at the University of Texas at Austin.

In recent years, the research group has supported the interface mechanics of nanomaterials under the support of the Ministry of Science and Technology, the National Natural Science Foundation of China, and the Chinese Academy of Sciences [Compos. Sci. Technol. 149 (2017) 220; Compos. Sci. Technol. 136 (2016) 1; ACS Appl. Mater. Inter. 8 (2016) 22554; Carbon 86 (2015) 69; Compos. Sci. Technol. 77 (2013) 101; Polymer 54 (2013) 456] and Nanocomposite Design [Small 29 (2017) In press; Carbon 121 (2017) 544; Carbon 121 (2017) 490; Adv. Funct. Mater. 26 (2016) 7003; Adv. Funct. Mater. 26 (2016) 303; Small 12 (2016) 3327; ACS Appl Mater. Inter. 8 (2016) 311; Sci. Rep. 6 (2016) 32989; Sci. Rep. 6 (2016) 18930; Nanoscale 7 (2015) 9252; Carbon 94 (2015) 101; Nanoscale 6 (2014) 6932; Nanoscale 5 (2013) 12171; Small 9 (2013) 2466] has achieved a number of research advances and a series of research results.

Based on this, the research group has expanded the application research of nanocomposites in important fields, and carried out cooperation and research and development with the backbone industries such as State Grid, China Commercial Aircraft, Carbon Valley Technology, Desai Group and Zhongtian Technology. Change.

(Original title: Advances in research on graphene atom-level interlaminar shearing)