Transparent and flexible cellulose nanofibers/silver nanowires/acrylic resin composite electrode

In this study, we report a novel, eco-friendly and simple method to fabricate cellulose nanofibers (CNFs)/silver nanowires (AgNWs)/acrylic resin (AR) composite electrode. CNFs with average diameter of 15 nm were disintegrated only by one time-pass grinding. Aqueous dispersion of AgNWs was embedded onto the surface of CNFs film by simple vacuum filtration. The final composite electrode was obtained by impregnating CNFs/AgNWs film to AR with the assist of adhesive tape. This electrode with AgNWs density of 134 mg/m² showed low sheet resistance (4 Ω/sq), and high light transmittance (85%) which was 6% lower than that of neat AR. The coefficient of thermal expansion of the composite electrode was as low as 25.32 ppm K⁻¹. The tensile strength and Young’s modulus of CNFs/AgNWs/AR composite film were 35.71 MPa and 1.63 GPa, which were about 8 and 5.8 times larger than neat AR film, respectively.     

Highly stretchable pseudocapacitors based on buckled reticulate hybrid electrodes

In order to develop an excellent pseudocapacitor with both high specific capacitance and outstanding stretchability to match with other devices applicable in future wearable and bio-implantable systems, we focus our studies on three vital aspects： Stretchability of hybrid film electrodes, the interface between different components, and the integrated performance in stretchability and electrochemistry of supercapacitors based on single-walled carbon nanotube/ polyaniline （SWCNT/PANI） composite films on pre-elongated elastomers. Owing to the moderate porosity, the buckled hybrid film avoids the cracking which occurs in conventional stretchable hybrid electrodes, and both a high specific capacitance of 435 F.g-1 and a high strain tolerance of 140% have been achieved. The good SWCNT/PANI interfacial coupling and the reinforced solid electrolyte penetration structure enable the integrated pseudocapacitors to have stretch- resistant interfaces between different units and maintain a high performance under a stretching of 120% elongation, even after 1,000 cyclic elongations.     

Size effect on the crystal structure of silver nanowires

A 4H structural silver nanowire (4H-AgNW) is discovered to coexist with a face-centered cubic (FCC) one prepared by electrochemical deposition and to have the highest concentration in the total of 4H- and FCC-AgNWs with diameters around 30 nm. Moreover, the concentration becomes smaller when the diameters deviate from 30 nm. This size effect arises from the fact that 4H-AgNW has a more favorable surface configuration but higher volume internal energy than FCC-AgNW, which is proved by our model.     

Highly conductive, printable and stretchable composite films of carbon nanotubes and silver

Conductive films that are both stretchable and flexible could have applications in electronic devices, sensors, actuators and speakers. A substantial amount of research has been carried out on conductive polymer composites, metal electrode-integrated rubber substrates and materials based on carbon nanotubes and graphene. Here we present highly conductive, printable and stretchable hybrid composites composed of micrometre-sized silver flakes and multiwalled carbon nanotubes decorated with self-assembled silver nanoparticles. The nanotubes were used as one-dimensional, flexible and conductive scaffolds to construct effective electrical networks among the silver flakes. The nanocomposites, which included polyvinylidenefluoride copolymer, were created with a hot-rolling technique, and the maximum conductivities of the hybrid silver-nanotube composites were 5,710 S cm?1 at 0% strain and 20 S cm?1 at 140% strain, at which point the film ruptured. Three-dimensional percolation theory reveals that Poisson's ratio for the composite is a key parameter in determining how the conductivity changes upon stretching.     

Highly conductive supercapacitor based on laser-induced graphene and silver nanowires

One of the foremost necessary desires of energy systems has been the existence of efficient, flexible, transportable, and eco-friendly devices. Among all the energy storage systems, supercapacitors have attracted plenty of attention thanks to their distinctive properties. Among all capacitor technologies, laser-induced graphene (LIG)-based capacitors are within the spotlight nowadays due to their high flexibility and simple manufacture. The most downside with LIG-based capacitors is their low conductivity and low charge capacity. During this work, to overcome this problem, the surface of LIG is covered with silver nanowires (AgNWs) and LIG/AgNWs composite is employed to form supercapacitor. In this study, all the electrochemical properties of the prepared composite were investigated, and therefore the results showed that AgNWs could increase the electrical conductivity of LIG by about 2.25 times, improve electrode–electrolyte interaction, and increase areal capacitance by 1.3 times. Additionally, the synthesized supercapacitor shows stable cyclic behavior and retention capacity equal to 78% after 1000 charge–discharge cycles. A singular increase in LIG conductivity and improved in its cyclic performance. Furthermore, galvanostatic charge/discharge curves indicated acceptable charge capacity of the LIG/AgNWs supercapacitor.

     

The synthesis and crystallization mechanism of protein-conjugated silver sulfide nanowires with hierarchical structure

The Bovine serum albumin (BSA)-conjugated silver sulfide (Ag₂S) nanowires with hierarchical structure were prepared under the gentle conditions by using BSA as the matrix and with the assistance of anodic aluminum oxide (AAO) templates. The high-resolution transmission electron microscope (HRTEM) showed the nanowires were with 50 nm in the diameter and several micrometers in the length and composed of nanoparticles with 10 nm in the diameter. The real-time observation by transmission electron microscope (TEM) displayed that the nano assemblies were formed from the smaller building blocks step by step.     

Flexible piezoelectric nanogenerators based on a fiber/ZnO nanowires/paper hybrid structure for energy harvesting

We present a novel, low-cost approach to fabricate flexible piezoelectric nano- generators （NGs） consisting of ZnO nanowires （NWs） on carbon fibers and foldable Au-coated ZnO NWs on paper. By using such designed structure of the NGs, the radial ZnO NWs on a cylindrical fiber can be utilized fully and the electrical output of the NG is improved. The electrical output behavior of the NGs can be optionally controlled by increasing the fiber number, adjusting the strain rate and connection modes. For the single-fiber based NGs, the output voltage is 17 mV and the current density is about 0.09 μA·cm^-2, and the electrical output is enhanced greatly compared to that of previous similar micro-fiber based NGs. Compared with the single-fiber based NGs, the output current of the multi-fiber based NGs made of 200 carbon fibers increased 100-fold. An output voltage of 18 mV and current of 35 nA are generated from the multi-fiber based NGs. The electrical energy generated by the NGs is enough to power a practical device. The developed novel NGs can be used for smart textile structures, wearable and self-powered nanodevices.     

填充银纳米线各向同性导电胶的性能

以Ti (OC₄H₉)₄ 水解形成的溶胶体系为模板, 以AgNO₃ 为银纳米线的前驱体, 低温下合成长径比为50～60 的银纳米线, 采用TEM 和XRD 对所制得的银纳米线进行表征。以银纳米线作为导电胶的导电填料, 成功制备了一种高电导率的各向同性导电胶。导电胶的电学性能和力学性能测试表明: 这种导电胶在导电填料含量为56 wt %时的电导率比填充75 wt %微米银粒子的导电胶高约6 倍(体积电阻率为1. 2 ×10-4Ω·cm) 。由于填料含量的降低, 该导电胶的抗剪切强度(以Al 为基板时的抗剪切强度为17. 6 MPa) 相比于填充75 wt %微米银粒子和75 wt %纳米银粒子导电胶均有不同程度的提高。      

Highly flexible transparent film heaters based on random networks of silver nanowires

We demonstrate a new concept for the fabrication of flexible transparent thin film heaters based on silver nanowires. Thanks to the intrinsic properties of random networks of metallic nanowires, it is possible to combine bendability, transparency and high heating performances at low voltage, typically below 12 V which is of interest for many applications. This is currently not possible with transparent conductive oxide technologies, and it compares well with similar devices fabricated with carbon nanotubes or graphene. We present experiments on glass and poly(ethylene naphthalate) (PEN) substrates (with thicknesses of 125 μm and extremely thin 1.3 μm) with excellent heating performances. We point out that the amount of silver necessary to realize the transparent heaters is very low and we also present preliminary results showing that this material can be efficiently used to fabricate photochromic displays. To our knowledge, this is the first report of metallic nanowire-based transparent thin film heaters. We think these results could be a useful approach for the engineering of highly flexible and transparent heaters which are not attainable by existing processes.      

基于材料选型优化的金属-复合材料组合结构-声辐射优化

基于金属铺层假设,以结构材料属性和材料铺层数量为设计变量,建立了基于金属-复合材料的材料选型结构-声辐射优化设计模型。以钢-纤维增强复合材料组合结构为例,开展了多设计变量、多约束条件的结构-声辐射优化研究。最后,采用遗传算法进行求解,实现了结构材料的转换。数值算例表明,通过金属-复合材料组合结构的材料选型优化,可以有效降低钢-纤维增强复合材料结构的振动和声辐射。文中的研究方法为结构材料的分布优化提供了一种可行有效的思路。     

Transparent conductive film having sandwich structure of gallium-indium-oxide/silver/gallium-indium-oxide

New transparent conductive films having the sandwich structure of gallium-indium-oxide/silver/gallium-indium-oxide (GIO/Ag/GIO) were prepared by conventional magnetron sputtering method at ambient substrate temperature. The electrical and optical properties of the films were compared with those of conventional indium-tin-oxide (ITO) films and ITO/Ag/ITO sandwich films. The GIO/Ag/GIO (40 nm/8 nm/40 nm) sandwich films, in which the GIO film was deposited using a GIO ceramic target with In content [In/(Ga + In)] of 10 at.%, exhibited a low sheet resistance of 11.3 Ω/sq and a large average transmittance of over 92.9% in the visible region (400-800 nm). This GIO/Ag/GIO films also exhibited a novel characteristic of transparency in the ultraviolet region; they showed high transmittance of 82.2% at the wavelength of 330 nm and 40.8% at the wavelength of 280 nm, which was not shown in the ITO films and the ITO/Ag/ITO sandwich films. The GIO/Ag/GIO sandwich films are useful as transparent electrode for emitting devices of ultraviolet radiation because of both their high conductivity and high transparency in the ultraviolet region.     

Intrinsically stretchable transparent electrodes based on silver-nanowire-crosslinked-polyacrylate composites

Stretchable transparent composites have been synthesized consisting of a silver nanowire (AgNW) network embedded in the surface layer of a crosslinked poly(acrylate) matrix. The interpenetrating networks of AgNWs and the crosslinked polymer matrix lead to high surface conductivity, high transparency, and rubbery elasticity. The presence of carboxylic acid groups on the polymer chains enhances the bonding between AgNWs and the polymer matrix, and further increases the stretchability of the composites. The sheet resistance of the composite electrode increases by only 2.3 times at 50% strain. Repeated stretching to 50% strain and relaxation only causes a small increase of the sheet resistance after 600 cycles. The morphology of the composites during reversible stretching and relaxation has been investigated to expound the conductivity changes.     

L-半胱氨酸诱导单晶银纳米线的快速合成及表征

采用化学还原法,以聚乙烯砒咯烷酮(PVP)为稳定剂和形貌控制剂,乙二醇为还原剂,在L-半胱氨酸诱导下,由硝酸银快速制备了银纳米线。采用紫外-可见吸收光谱、X射线衍射、扫描电子显微镜、选区电子衍射和透射电子显微镜手段对所得产物进行表征,结果表明利用L-半胱氨酸诱导可在15min内制备直径为100nm左右,长度约几百微米的银纳米线,并具有单晶结构,根据实验结果提出了可能的银纳米线快速合成机理。     

Effect of silver nanowires on electrical conductance of system composed of silver particles

Silver nanowires were prepared by polyol process and doped to the system containing conventional micro-scaled sphere or flake silver particles. It is found that the conductance of doped system is much better than the undoped system with the same quantity silver. A plausible mechanism is described as that these nanowires are favor to act as bridges to establish perfect linkage among particles, and the chance of contact and contact area become more than the cases without wires. This development will be meaningful for the preparation of advanced electrically conductive adhesive (ECA) with high conductivity and good adhesive strength.     

Vibration in a satellite structure with a laminate composite hybrid sandwich panel

The objective of this investigation is to study the complex vibration characteristics of an actual spacecraft structure using the FEA code in conjunction with experimental data. The body of a satellite consists of a monocoque structure formed by joining several composite sandwich panels composed of an aluminum honeycomb core with carbon fiber reinforced laminate skins on both sides.     

Isotropical conductive adhesives with very-long silver nanowires as conductive fillers

Isotropical conductive adhesives (ICAs) have garnered great attention from the researchers in electronic industry as a potential substitute to lead-bearing solders for novel microsystem. In this paper, silver nanowires with a diameter of approximately 390 nm and a length of over 100 μm were synthesized by a polyol process. The ICAs composed of an epoxy-based binder containing silver nanowire were prepared and the curing behaviors, electrical properties, hygroscopicity, and the tensile shear strength of ICAs were investigated. Silver nanowires affect the curing behavior of epoxy resin and reduce the cross-linking density. The resistivity of the ICAs filled with 10, 35 and 45 wt% silver nanowire cured at 150 °C is 8.9 × 10^?3, 1.69 × 10^?5 and 4.9 × 10^?6 Ω cm respectively. The resistivity of the ICAs filled with silver nanowire cured at 150 °C is little change after aged under 85 °C/85 % for 264 h. With the increase of the loading of silver nanowire the tensile shear strength of the ICAs increase. The reasons for the effects of silver nanowires on the curing behavior and the electrical property and hygroscopicity and the tensile shear strength were discussed in terms of the morphology, distribution, and higher activity of silver nanowires.