Ordered mesoporous In2O3 gas-sensing materials with controlled mesostructured morphology and high thermal stability have been successfully synthesized via a nanocasting method in conjunction with the container effect. The mesostructured ordering, as well as the particle size, crystallinity and pore size distribution have been proved to vary in a large range by using the XRD, SAXRD, SEM, TEM, and nitrogen physisorption techniques. The control of the mesostructured morphology was carried out by tuning the transportation rate of indium precursor in template channel resulting from the different escape rate of the decomposed byproducts via the varied container opening and shapes. The particular relation between the mesostructured ordering and gas sensing property of mesoporous In2O3 was examined in detail. It was found that the ordered mesoporous In2O3 with appropriate mesostructured morphology exhibited significantly improved ethanol sensitivity, response and selectivity performances in comparison with the other ordered mesoporous In2O3, which benefits from the large surface area with enough sensing active sites, proper pore distribution for sufficient gas diffusion, and appropriate particle size for effective electron depletion. The resulting sensing behaviors lead to a better understanding of designing and using such mesoporous metal oxides for a number of gas-sensing applications.
Realizing ultra-fast charge and discharge of lithium-ion batteries (LIBs) is one of the effective ways to promote the popularity of electric vehicles, solve energy and environmental problems. A lot of studies have shown that low conductivity and low lithium-ion diffusivity are the major limiting factors for the rate performance of cathode. However, there is no systematic review on the methods to improve the rate performance of cathode for LIBs. Hence this review ground-breakingly summarizes a series of key strategies and their electrochemical mechanisms to increase the rate capacity of cathode materials. The limiting factors for the development of LIBs fast charging are introduced. It analyzes the working mechanisms of the nanostructure and micro-nanostructures. The influences of carbon coating with different carbon sources are introduced and compared in detail. The specific mechanisms and research results of surface coating modification and doping strategies in LiFePO4, layered structure cathode, and spinel structure cathode are reviewed. Moreover, innovative approaches such as spinel-layered composites preparation, structural-gradient design, and photo-accelerated fast charging are also provided. Finally, some existing challenges and development directions in the future are discussed.
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