In‐Plane Potential Gradient Induces Low Frictional Energy Dissipation during the Stick‐Slip Sliding on the Surfaces of 2D Materials

Abstract

Understanding the nanoscale friction properties of 2D materials and further manipulating their friction behaviors is of great significance for the development of various micro/nanodevices. Recent studies, taking advantage of the close relationship between friction and surface charges, use an external out‐of‐plane electric field to control the interfacial friction. Nevertheless, friction increases with the application of the out‐of‐plane electric field in most cases. Here, an in‐plane potential gradient is applied for the investigation of the contribution of electric charges to friction on the surfaces of 2D materials. Experimental results show that the friction between an atomic force microscope tip and the flakes of 2D materials decreases with the application of the in‐plane potential gradient, and the higher the potential gradient, the greater the friction decrease. By comparing the in situ atomic‐level stick‐slip maps before and after the application of the in‐plane potential gradient, it is proposed that the promotion of low friction dissipative motion during the stick‐slip process owing to the presence of the potential gradient gives rise to the friction reduction. These results not only help to reveal the origin of friction, but also provide a novel way to manipulate friction through an electrically‐controlled sliding process.

Electro-lubrication in Janus transition metal dichalcogenide bilayers

“…Many effective methods, such as designing interfacial or contacting structures, decreasing surface roughness and mechanical loading, and adding solid or liquid lubricant additives, have been developed to control and reduce friction and wear. Previous studies have shown that applying external electric fields can modify the molecular structure and charge transfer at solid-solid interfaces, thereby decreasing the interfacial friction and resistance [1,2]. Moreover, the distribution or orientation of ions at solid-liquid interfaces can be controlled and changed via electric fields to achieve the desired lubricating effect [3][4][5][6][7].…”

Nanofriction characteristics of h-BN with electric field induced electrostatic interaction

“…The potential difference between AFM tips with different conductivities and samples was applied to study bias-dependent friction using conductive AFM [38,39]. In addition, Fann et al [40] reported electron dynamics and thermalization in metals and semiconductors on timescales, providing an exciting possibility to control the nanofriction of h-BN by using charges.…”

Effect of electric fields in low-dimensional materials: Nanofrictional response as a case study

“…Previous studies already pointed out that load can be used as an external knob to control the nanoscale friction [11][12][13], although it may induce unwanted permanent changes to the atomic geometry [14][15][16][17]. On the other hand, electrical fields induce charge movements which may alter the frictional properties temporarily, while allowing them to revert to the original structure once the external field is suppressed [18][19][20]. Some theoretical studies have already dealt with the effect of electric fields on the coupling between the electronic and dynamic (i.e., phonon) features in low-dimensional materials [21,22]; interestingly, such coupling has been found to be effective in altering the lateral frictional force in MoS 2 and graphene bilayer systems [23,24].…”

“…Some theoretical studies have already dealt with the effect of electric fields on the coupling between the electronic and dynamic (i.e., phonon) features in low-dimensional materials [21,22]; interestingly, such coupling has been found to be effective in altering the lateral frictional force in MoS 2 and graphene bilayer systems [23,24]. Recent experimental studies showed how to manipulate free-standing atomic layers by in-plane potential gradients with an atomic force microscopy tip [6,25], while the friction between the tip and the layer decreases with the field [20].…”