Search

K metal batteries, with high electrochemical performance and low-cost, hold great potential to be one of alternatives to lithium-ion batteries. However, the intrinsic high reactivity of K metal electrode limits their application. To enhance the safety of K metal batteries, a graphite-intercalation-compound of K (K-GIC) is prepared as an anode instead of K metal in this work. The K-GIC symmetric batteries show excellent cycling stability due to suppressing dendrite and alleviating volume expansion which are resulted from the interlayer insertion/extraction mechanism and reduced affinity energy of K. Moreover, the K-GIC compound exhibits good environmental stability in contact with air and water. Our work shows that K-GIC as an anode material may promote the application of safe and high-performance K metal batteries.

A new Mg–10%Al–1%Zn–1%Si alloy with non-dendritic microstructure was prepared by strain induced melt activation (SIMA) process. The effect of compression ratio on the evolution of semisolid microstructure of the experimental alloy was investigated. The results indicate that the average size of α-Mg grains decreases and spheroidizing tendency becomes more obvious with the compression ratios increasing from 0 to 40%. In addition, the eutectic Mg2Si phase in the Mg–10%Al–1%Zn–1%Si alloy transforms completely from the initial fishbone shape to globular shape by SIMA process. With the increasing of compression ratio, the morphology and average size of Mg2Si phases do not change obviously. The morphology modification mechanism of Mg2Si phase in Mg–10%Al–1%Zn– 1%Si alloy by SIMA process was also studied.

A new cobalt(II)-catalyzed decarboxylative C-H activation/annulation of benzamides and alkynyl carboxylic acids has been described. Alkynyl carboxylic acids were first employed as the coupling partners using inexpensive Co(OAc)2·4H2O as the catalyst. This method enables a switchable cyclization to isoquinolones and isoindolinones with excellent selectivity. Moreover, a catalytic amount of Ag2O was adopted as co-catalyst and O2 (from air) as a terminal oxidant for the preparation of isoquinolones.

In recent years, instant messaging tools have become one of the main channels for people to communicate, and WeChat is one of the most important members. Since WeChat was launched, monthly active users have exceeded 1 billion. In January 2015, WeChat friends circle advertisement was officially launched and used in the form of information flow advertisement, which users praised or criticized differently. Therefore, it is a problem that WeChat research and development team and advertisers must face to improve users' willingness to accept advertisements in the circle of friends. We used “WeChat” and “circle of friends” as key words to search in CNKI, and the number of articles retrieved was 205. After carrying out quantitative analysis and content analysis of relevant documents (2013 – 2018), it is found that most of the studies were carried out from the perspective of the communication mechanism, marketing strategy and comparative analysis of advantages and disadvantages of WeChat circle of friends. In addition, some studies are based on advertisement avoidance, user participation and willingness to accept. At the same time, we also take WeChat as the research background, integrate the development and changes of TAM (technology acceptance model), and summarize the basic situation of users' willingness to accept WeChat friends' circle advertisement in our country so as to provide more direction and space for the optimization research of WeChat friends' circle advertisement.

Aligned spinel Mn-Ni-Co ternary oxide (MNCO) nanowires are synthesized by a facile hydrothermal method. As an electrode of supercapacitors, the MNCO nanowire array on nickel foam shows an outstanding specific capacitance of 638 F g(-1) at 1 A g(-1) and excellent cycling stability. This exceptional performance benefits from its nanowire architecture, which can provide large reaction surface area, fast ion and electron transfer, and good structural stability. Furthermore, an asymmetric supercapacitor (ASC) with high energy density is assembled successfully by employing the MNCO nanowire array as positive electrode and carbon black as negative electrode. The excellent electrochemical performances indicate the promising potential application of the ASC device in the energy storage field.

A TiO2/NiO core/shell nanorod array film is prepared by the combination of hydrothermal and chemical-bath deposition. Compared to the NiO nanoflake film, the TiO2/NiO core/shell nanorod array exhibits better electrochromism with reversible color changes bewteen transparency and dark brown, shows larger optical modulation (83%), higher coloration efficiency (60.6 cm2 C1–) and better cycling performance. The enhancement of electrochromic performances is attributed to the synergetic contribution from the single crystalline TiO2 nanorod core and the ultrathin NiO nanoflake shell, as well as the ordered array geometry, which can all offer direct electrical pathways for electrons and increase the electron transport rate.

A vertically aligned hierarchical WO3 nanosheet array on a transparent conducting substrate is produced via a template-free and capping-agent-free hydrothermal method. Due to its high porosity among the nanosheets and good contact with the conductive substrate, the WO3 nanosheet film exhibits advantageous electrochemical abilities. For example, fast switching speed (5.2 and 2.2 s for coloration and bleaching, respectively), significant optical modulation (62% at 633 nm and 67% at 2000 nm), high coloration efficiency of 55.6 cm2 C−1 at 700 nm and excellent cycling stability (95.4% after 3000 cycles) are achieved for the WO3 nanosheet array film in electrochromic application. In addition, the nanosheet film also shows outstanding electrocatalytic ability for chemical reduction of H2O2.

Co-doped NiO electrochromic nanoflake array films grown on FTO with antireflection ability have been synthesized by low temperature chemical bath deposition. Co doping has an influence on the growth and electrochromic properties of NiO nanoflake arrays. Noticeably, all the films show a very high transmittance at the bleached state in the region of visible light. Compared to the undoped NiO, the 1% Co-doped NiO nanoflake array film exhibits outstanding electrochromism, including large transmittance modulation (88.3%), high coloration efficiency (47.7 cm2 C−1), fast switching speed (3.4 s and 5.4 s), excellent reversibility and cycling durability at a wavelength of 550 nm. The enhanced electrochromic performances can be attributed to the synergetic effect contribution from low crystallization, oblique nanoflake array configuration and improved p-type conductivity by appropriate Co doping.

Hierarchical SnO2@NiO core/shell nanoflake array on FTO-coated glass has been synthesized by a facile two-step solution method toward energy-saving electrochromism. Noticeably, the SnO2@NiO core/shell nanoflake array film shows a sustained memory effect, which is conducive to saving energy in commercial applications. The SnO2@NiO film exhibits an outstanding electrochromism, including large transmittance modulation (85.3%), fast switching speed (1.7 s and 2.4 s), high coloration efficiency (43.8 cm2 C−1), and excellent reversibility and cycling durability at 550 nm. The enhanced electrochromic performances can be attributed to the unique core/shell architecture, which provides large numbers of active sites for electrochemical reactions, fast ion and electron transfer channels and good strain accommodation ability.

The TiO2@PANI core/shell nanorod array is prepared by the combination of hydrothermal and electro-polymerization methods. A significant optical modulation (57.6% at 700 nm), high coloration efficiency (37.1 cm2 C–1), and good cycling performance (62.1% after 1000 cycles) are achieved for the TiO2@PANI core/shell nanorod array. The improved electrochromic properties are mainly attributed to the core/shell structure, formation of the donor–acceptor system, and the porous space among the nanorods, which can reduce the oxidation potential, make the ion diffusion easier and provide larger surface area for charge-transfer reactions. The data indicate great promise for the TiO2@PANI core/shell nanorod array as a potential multicolor electrochromic material.

Hierarchical structure Ti-doped WO3 thin films are prepared by a template-free hydrothermal method. The influence of Ti doping on the electrochromic properties of WO3 thin films is investigated in the visible-infrared region. Ti doping can lead to significant surface morphology change and lower the crystallization, which plays an important role in the electrochromic properties of WO3 films. The large transmittance modulation (49.1% at 750 nm, 64.6% at 2000 nm and 59.3% at 10 μm), fast switching speed (1.7 s and 1.6 s) and high coloration efficiency (68 cm2 C−1 at 750 nm) are achieved for the low Ti-doped WO3 film. The enhancement in the electrochromic performance of the low Ti-doped WO3 films is attributed to their low crystallization, a star-like structure which has low charge transfer and ion diffusion resistance, leading to superior electrical conductivity and reaction kinetics.

Nanostructured NiO thin films were directly prepared by simple and efficient electrodeposition in a choline chloride-based ionic liquid. Uniform granules and some open voids between these granules are observed in the film deposited at 70 °C, while the film becomes compact and the NiO particles are 2–6 nm in size when the electrodeposition temperature is 90 °C. The optical transmittance of the film increased with the increase of the electrodeposition temperature. Although the electrochromic switching and reaction kinetics of the NiO film deposited at low temperature are fast due to the presence of metallic Ni and some voids, little transmittance modulation occurs in the wavelength range of 300–900 nm. In contrast, the NiO film deposited at high temperature exhibits high optical modulation of 67% at 550 nm, high coloration efficiency (98 cm2 C−1 at 400 nm, 92 cm2 C−1 at 550 nm and 51 cm2 C−1 at 750 nm), good memory effect and cycling durability.