Jun 2019, Volume 13 Issue 2

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    Rongrong JIANG, Ming LI, Yirong YAO, Jianmin GUAN, Huanming LU

    For the accuracy of experimental results, preparing a high quality polished surface and cross-section of the materials for further analysis using electron backscattered diffraction (EBSD), electron probe microanalysis (EPMA), and scanning probe microscopy (SPM) is extremely important. Broad ion beam (BIB) polishing, a method based on the principle of ion bombardment, has irreplaceable advantages. It makes up for the drawbacks and limitations of traditional polishing methods such as mechanical polishing, electrochemical polishing, and chemical polishing. The ions will not leave the bombardment area during polishing, which makes the BIB method suitable for porous materials. The energy of the ion beam can be adjusted according to the sample to reduce the deformation and strain of the polishing area, especially for fragile, soft, and hard materials. The conditions that need to be controlled during BIB polishing are simple. This paper demonstrated the unique advantages of BIB polishing technology in porous, layered and powder materials characterization through some typical application examples, and guided more researchers to understand and utilize BIB polishing technology in the development of new applications.

    Chengzhi YANG, Shikun CHEN, Huilan SU, Haoyue ZHANG, Jianfei TANG, Cuiping GUO, Fang SONG, Wang ZHANG, Jiajun GU, Qinglei LIU

    Biocompatible, small-sized but well-dispersed gold nanoparticles (Au NPs) remain a major challenge for their synthesis. Here a convenient solution impregnation technique is developed to prepare such Au NPs under the regulation of degummed silk fibroin fibers (SFFs) extracted from Bombyx mori cocoons. SFFs play multiple roles in the formation of Au NPs such as reactive substrate to capture AuCl4 ions by the chelation of −C=O, reducing agent for Au(0) by the reduction of −OH, and modifiers to render biocompatible Au NPs by some functional groups and biomolecules. The as-prepared Au NPs with a size of 7–10 nm are embedded in the solid SFF substrate, and can disperse well in the liquid system by the disintegration of SFFs into silk fibroin (SF) in a certain CaCl2 solution. The biocompatible Au NPs exhibit uniform small size and distribute stably in both solid and solution states, which have distinctive properties and functional advantages, and bring great convenience to their storage and transportation.

    Ge JU, Muhammad Arif KHAN, Huiwen ZHENG, Zhongxun AN, Mingxia WU, Hongbin ZHAO, Jiaqiang XU, Lei ZHANG, Salma BILAL, Jiujun ZHANG

    Porous polyaniline (PANI) was prepared through an efficient and cost-effective method by polymerization of aniline in the NaCl solution at room temperature. The resulting PANI provided large surface area due to its highly porous structure and the intercrossed nanorod, resulting in good electrochemical performance. The porous PANI electrodes showed a high specific capacitance of 480 F∙g−1, 3 times greater than that of PANI without using the NaCl solution. We also make chemically crosslinked hydrogel film for hydrogel polymer electrolyte as well as the flexible supercapacitors (SCs) with PANI. The specific capacitance of the device was 234 F∙g−1 at the current density of 1 A∙g−1. The energy density of the device could reach as high as 75 W∙h∙kg−1 while the power density was 0.5 kW∙kg−1, indicating that PANI be a promising material in flexible SCs.

    Bin CAI, Changxiang SHAO, Liangti QU, Yuning MENG, Lin JIN

    A novel type of sulfur-doped graphene fibers (S-GFs) were prepared by the hydrothermal strategy, the in situ interfacial polymerization method and the annealing method. Two S-GFs were assembled into an all-solid-state fibriform micro-supercapacitor (micro-SC) that is flexible and has a high specific capacitance (4.55 mF·cm−2) with the current density of 25.47 μA·cm−2. The cyclic voltammetry (CV) curve of this micro-SC kept the rectangular shape well even when the scan rate reached 2 V·s−1. There is a great potential for this type of S-GFs used in flexible wearable electronics.

    Meng LIU, Lei LIU, Yifeng YU, Haijun LV, Aibing CHEN, Senlin HOU

    Nitrogen-doped carbon spheres (NCSs) with uniform and regular morphology were facilely prepared by the modified Stöber method. Hexamethylenetetramine (HMT) was selected as the starting material, which decomposed to provide nitrogen and carbon sources for the synthesis of NCSs. The decomposition product formaldehyde polymerized to form carbon skeleton with resorcinol after carbonization, and the in-situ nitrogen doping was achieved with the decomposed nitrogen source. NCSs were obtained with regular spherical morphology, high specific surface area, and suitable nitrogen doping. When used as the electrode material, NCSs exhibited good capacitance and electrochemical stability, indicating that NCSs be the promising candidate for the electrode material of high-performance supercapacitors.

    Heng CHEN, Yun CHEN, Hang ZHAN, Guang WU, Jian Ming XU, Jian Nong WANG

    Based on the production of a carbon nanotube (CNT) assembly, a new technique is developed for preparing CNT/epoxy (EP) composite films with high tensile strength and electrical conductivity. CNTs are synthesized by floating catalyst spray pyrolysis. After self-assembling into a hollow cylindrical assembly, CNTs are drawn and wound on a rotating drum to form a uniform CNT film. EP resin solutions of different concentrations are used to fill into the pores within the film under different pressures and form composite films after hot-press curing. The permeability of the EP resin and thus the interfacial bonding between the CNT and the EP resin are studied by varying the concentration of the EP resin solution and the pressure used for impregnation. Under optimal preparation conditions, the composite film contains CNTs of a high content of 59 wt.%, and shows a high tensile strength of 1.4 GPa and a high electrical conductivity of 1.4×105 S·m−1, 159% and 309% higher than those of the neat CNT film, respectively.

    Chao WANG, Wu WANG, Ke HE, Shantang LIU

    Nanocubes derived from pure In2O3 and xPr-In2O3 (x= 1, 2, 3 and 5 mol.%) were synthesized using a facile hydrothermal method, followed by calcination. The morphological and structural characterization demonstrated that as-synthesized samples presented regular cubes that decreased in size with the increase of the Pr doping. The data showed that the sensing performances of sensors based on In2O3 were notably improved after the Pr doping. Among them, the sensor based on 2 mol.% Pr-In2O3 had the best sensing performance towards the triethylamine (TEA) gas, including a high response (Ra/Rg = 260 to 100 ppm TEA gas, which is about 12 times higher than that of the sensor based on pure In2O3), a short response time (2 s), and a low detection limit (0.2 ppm) at 350 °C. The mechanism responsible for the enhancement of sensing performance was attributed to the improvement of the vacancy content of 2 mol.% Pr-In2O3, which promoted the oxidation–reduction reaction with the TEA gas that occurred on the materials surface.

    Ruiping LIU, Ning ZHANG, Xinyu WANG, Chenhui YANG, Hui CHENG, Hanqing ZHAO

    Lithium-ion batteries (LIBs) with high energy density have attracted great attention for their wide applications in electric vehicles, and the exploration of the next-generation anode materials with high theoretical capacity is highly desired. In this work, SnO2 nanoparticles with the particle size of 200 nm uniformly anchored on the surface of graphene oxide (GO) was prepared by combination of the ultrasonic method and the following calcination process. The SnO2/GO composite with the weight ratio of SnO2 to GO at 4:1 exhibits excellent electrochemical performance, which originates from the synergistic effects between GO and SnO2 nanoparticles. A high discharge capacity of 492 mA·h·g−1 can be obtained after 100 cycles at 0.2C, and after cycling at higher current densities of 1C and 2C, a discharge capacity of 641 mA·h·g−1 can be restored when the current density goes back to 0.1C. The superior electrochemical performance and simple synthesis process make it a very promising candidate as anode materials for LIBs.

    Heling GUO, Xiaolin WANG, Xie LI, Xiulan ZHANG, Xinghuan LIU, Yu DAI, Rongjie WANG, Xuhong GUO, Xin JIA

    Phenolic-metal complexation coatings have been discovered to be a universal route for the deposition of multifunctional coatings. However, most complexation coatings have been prepared by the immersion method, which limits their practical large-scale application. Herein, we describe a facile and green engineering strategy that involves spraying phenolic compound and metal ions on substrate to form in-situ complexation coating with different coordination states. The coating is formed within minutes and it can be achieved in large scale by the spray method. The pyrogallol-FeIII complexation coating is prepared at pH 7.5, which consists predominantly of bis-coordination complexation with a small amount of tris-coordination complexation. It displays that the water contact angle is near zero due to the generation of rough hierarchical structures and massive hydroxyl groups. The superhydrophilic cotton resulting from the deposition of the pyrogallol-FeIII complexation can separate oil/water mixtures and surfactant-stabilized oil-in-water emulsions with high separation efficiency. The formation of the phenolic-metal complexation coating by using spray technique constitutes a cost-effective and environmentally friendly, strategy with potential to be applied for large-scale surface engineering processes and green oil/water separation.

    Hongquan ZHAN, Chuanqi WU, Ce DENG, Xiaohong LI, Zhipeng XIE, Changan WANG

    A kind of enhancing mechanism of structural whiteness dependence on amorphous photonic crystal (APC) structure is introduced in this paper. In the glaze system composed of albite, kaolin, talc, calcite, quartz, titanium dioxide and zinc oxide, the APC structure will be produced by using quartz as a variable to induce the phase separation. Under different polarities between Ti, Zn etc. and Si ion, the separated spheres with the core–shell structure can be obtained and then make up opal-like APCs in the glaze layer. In addition to inner and outer layers of core–shell spheres, the calculated results of refractive indices clearly show the great difference between the particles and the matrix. As a result of different refractive indices, the multiple scatting of visible light plays a key role in the structural whiteness. However, due to the decrease of the cationic content, APCs with the reverse opal structure would be formed in the interface between glaze and body. Ultimately, the glaze appearance reveals extremely high structural whiteness due to the special APC structure.