The use of nanomaterials for strain sensors has attracted attention due to their unique electromechanical properties. However, nanomaterials have yet to overcome many technological obstacles and thus are not yet the preferred material for strain sensors. In this work, we investigated graphene woven fabrics (GWFs) for strain sensing. Different than graphene films, GWFs undergo significant changes in their polycrystalline structures along with high-density crack formation and propagation mechanically deformed. The electrical resistance of GWFs increases exponentially with tensile strain with gauge factors of ~103 under 2~6% strains and ~106 under higher strains that are the highest thus far reported, due to its woven mesh configuration and fracture behavior, making it an ideal structure for sensing tensile deformation by changes in strain. The main mechanism is investigated, resulting in a theoretical model that predicts very well the observed behavior.

Through experimental study, we reveal superlubricity as the mechanism of self-retracting motion of micrometer sized graphite flakes on graphite platforms by correlating respectively the lock-up or self-retraction states with the commensurate or incommensurate contacts. We show that the scale-dependent loss of self-retractability is caused by generation of contact interfacial defects.A HOPG structure is also proposed to understand our experimental observations, particularly in term of the polycrystal structure. The realisation of the superlubricity in micrometer scale in our experiments will have impact in the design and fabrication of micro/nanoelectromechanical systems based on graphitic materials. Nano-mechanical devices based on van de Waals forces in multi-walled carbon nanotubes (MWCNT) and HOPG (i.e., multilayered graphenes) have attracted intensive experimental and theoretical studies, owing to their superior properties, e.g., the nearly `freely' motion of inner shell inside the outer shell of a MWCNT [1,2,3], the MWCNT based oscillator with GHz resonance frequency [4], the extremely fast self-retraction motion of graphite flakes in HOPG islands [5] and so on. The role of the interlayer van de Waals interaction in driving the motion of such van de Waals devices has been well recognised and studied by various theoretical analysis and molecular dynamic simulations [3,4,6,7]. On the other hand, the interlayer van de Waals interactions also leads to potential corrugations due to the periodic atomic structures of the graphene layers, and in turn results in the interlayer friction/resistance force. The role of such friction force in the van de Waals micro/nano-mechanical devices, however, is largely overlooked and there is no experimental studies in micrometer scale up to now (except few scanning probe microscope (SPM) experiments with nanoscale sharp tip scanning on top of a graphene [8,9,10,11]). In this Letter, we will reveal the decisive role of such friction force in the van de Waals nano-mechanical devices. Our resultsshow that the superlubricity, as a result of the incommensurate contact of different graphene layers, is the necessary condition for the self-driven motion of CNT/graphene based micro/nanomechanical devices.Superlubricity is a phenomenon that friction force vanish or almost vanish when two solid surfaces are sliding over each other [12], and has attracted many attentions [13,14,15,16] since the introduction of the concept [17]. The structural incommensurate between two crystalline solid

Despite interlayer binding energy is one of the most important material properties for graphite, there is still lacking report on its direct experimental determination. In this paper, we present a novel experimental method to directly measure the interlayer binding energy of highly oriented pyrolytic graphite (HOPG). The obtained values of the binding energy are 0.27(±0.02)J/m 2 , which can serve as a benchmark for other theoretical and experimental works.

Tailoring and assembling graphene into functional macrostructures with well-defined configuration are key for many promising applications. We report on a graphene-based woven fabric (GWF) prepared by interlacing two sets of graphene micron-ribbons where the ribbons pass each other essentially at right angles. By using a woven copper mesh as the template, the GWF grown from chemical vapour deposition retains the network configuration of the copper mesh. Embedded into polymer matrices, it has significant flexibility and strength gains compared with CVD grown graphene films. The GWFs display both good dimensional stability in both the warp and the weft directions and the combination of film transparency and conductivity could be optimized by tuning the ribbon packing density. The GWF creates a platform to integrate a large variety of applications, e.g., composites, strain sensors and solar cells, by taking advantages of the special structure and properties of graphene.

Since the appearance of semiconductor solid-state lasers in the 1960s, [1] lasers have shown tremendous potential in various applications, such as data communication, medical treatment, environmental science, and military defense. Up to now, enormous research efforts have been conducted to develop high-quality semiconductor lasers. [2] Multiple-mode lasers suffer from false signaling, random fluctuation, and instability which hinder their practical applications. [3,4] Therefore, efforts to achieve single-mode lasers have drawn much attention due to the monochromaticity, high stability, controllable output wavelength, and great potential of these lasers in practical applications, such as in on-chip optical communication. [5] Thus far, most single-mode lasers have been realized in the following four ways: 1) decreasing the cavity size to enlarge the free spectral range (FSR); [6,7] 2) fabricating distributed Bragg reflector (DBR) mirror structures or distributed feedback (DFB) CsPbBr 3 shows great potential in laser applications due to its superior optoelectronic characteristics. The growth of CsPbBr 3 wire arrays with well-controlled sizes and locations is beneficial for cost-effective and largely scalable integration into on-chip devices. Besides, dynamic modulation of perovskite lasers is vital for practical applications. Here, monocrystalline CsPbBr 3 microwire (MW) arrays with tunable widths, lengths, and locations are successfully synthesized. These MWs could serve as high-quality whispering-gallery-mode lasers with high quality factors (>1500), low thresholds (<3 µJ cm −2 ), and long stability (>2 h). An increase of the width results in an increase of the laser quality and the resonant mode number. The dynamic modulation of lasing modes is achieved by a piezoelectric polarization-induced refractive index change. Single-mode lasing can be obtained by applying strain to CsPbBr 3 MWs with widths between 2.3 and 3.5 µm, and the mode positions can be modulated dynamically up to ≈9 nm by changing the applied strain. Piezoelectric-induced dynamic modulation of single-mode lasing is convenient and repeatable. This method opens new horizons in understanding and utilizing the piezoelectric properties of lead halide perovskites in lasing applications and shows potential in other applications, such as on-chip strain sensing.

A sheared microscopic graphite mesa retracts spontaneously to minimize interfacial energy. Using an optical knife-edge technique, we report first measurements of the speeds of such self-retracting motion (SRM) from the mm/s range at room temperature to 25 m/s at 235°C [corrected]. This remarkably high speed is comparable with the upper theoretical limit found for sliding interfaces exhibiting structural superlubricity. We observe a strong temperature dependence of SRM speed which is consistent with a thermally activated mechanism of translational motion that involves successive pinning and depinning events at interfacial defects. The activation energy for depinning is estimated to be 0.1-1 eV.

A novel two-dimensional cationic framework [Zn(TCA)(BIB)]·(NO) (1) (HTCA = tricarboxytriphenyl amine, BIB = 1,3-bis(imidazol-1-ylmethyl)benzene) was successfully achieved. Compound 1 not only presents a moderate affinity toward CO molecules, but it also displays good catalytic performance and substrate selectivity toward both CO conversion with epoxides and Knoevenagel condensation under solvent-free environments, taking advantage of the Lewis acidity endowed by lower four-coordinated Zn(II) centers and Lewis basicity originated from the amines within TCA. More importantly, the bifunctional heterogeneous catalyst compound 1 shows easy recovery and reuse without an obvious decrease of activity. Strikingly, compound 1 exhibits good catalytic efficiency for CO coupled with propylene oxide forming propylene carbonate even at ambient temperature under 1 atm pressure. To the best of our knowledge, compound 1 is presented to be the first cationic MOF holding great promise as a heterogeneous solvent-free catalyst toward both CO epoxidation and Knoevenagel condensation reaction.

The coumarin-based probe Cu(II)-COT1 was successfully developed for the detection of HNO on the basis of the reduction reaction. In addition, highly selective "turn on" type fluorogenic behavior upon the addition of Angeli's salt (Na(2)N(2)O(3)) was also applied to bioimaging in A375 cells.