Progress on mechanical and tribological characterization of 2D materials by AFM force spectroscopy

Two-dimensional(2D)materials are potential candidates for electronic devices due to their unique structures and exceptional physical properties,making them a focal point in nanotechnology research.Accurate assessment of the mechanical and tribological properties of 2D materials is imperative to fully exploit their potential across diverse applications.However,their nanoscale thickness and planar nature pose significant challenges in testing and characterizing their mechanical properties.Among the in situ characterization techniques,atomic force microscopy(AFM)has gained widespread applications in exploring the mechanical behaviour of nanomaterials,because of the easy measurement capability of nano force and displacement from the AFM tips.Specifically,AFM-based force spectroscopy is a common approach for studying the mechanical and tribological properties of 2D materials.This review comprehensively details the methods based on normal force spectroscopy,which are utilized to test and characterize the elastic and fracture properties,adhesion,and fatigue of 2D materials.Additionally,the methods using lateral force spectroscopy can characterize the interfacial properties of 2D materials,including surface friction of 2D materials,shear behaviour of interlayers as well as nanoflake-substrate interfaces.The influence of various factors,such as testing methods,external environments,and the properties of test samples,on the measured mechanical properties is also addressed.In the end,the current challenges and issues in AFM-based measurements of mechanical and tribological properties of 2D materials are discussed,which identifies the trend in the combination of multiple methods concerning the future development of the in situ testing techniques.

A Nonresonant Hybridized Electromagnetic-Triboelectric Nanogenerator for Irregular and Ultralow Frequency Blue Energy Harvesting

As a promising renewable energy source,it is a challenging task to obtain blue energy,which is irregular and has an ultralow frequency,due to the limitation of technology.Herein,a nonresonant hybridized electromagnetic-triboelectric nanogenerator was presented to efficiently obtain the ultralow frequency energy.The instrument adopted the flexible pendulum structure with a precise design and combined the working principle of electromagnetism and triboelectricity to realize the all-directional vibration energy acquisition successfully.The results confirmed that the triboelectric nanogenerator(TENG)had the potential to deliver the maximum power point of about 470μW while the electromagnetic nanogenerator(EMG)can provide 523 mW at most.The conversion efficiency of energy of the system reached 48.48%,which exhibited a remarkable improvement by about 2.96 times,due to the elastic buffering effect of the TENG with the double helix structure.Furthermore,its ability to collect low frequency wave energy was successfully proven by a buoy in Jialing River.This woke provides an effective candidate to harvest irregular and ultralow frequency blue energy on a large scale.

Surface Plasmon Effect Dominated High-Performance Triboelectric Nanogenerator for Traditional Chinese Medicine Acupuncture

Available,effectively converting low-frequency vibration into available electricity,triboelectric nanogenerator(TENG)is always research hot nowadays.However,the enhancing effect of the existing methods for the output have all sorts of drawbacks,i.e..