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Photocatalysis is a new type of renewable energy technology used in environmental treatment and hydrogen energy production. In this regard, a new class of photocatalysts, TiO2 aerogels, are attractive for having the chemical characteristics of TiO2 nanomaterials such as high catalytic activity, good stability, non-toxic, and non-polluting, and the structural characteristics of aerogels such as large specific surface area, high porosity, the 3-dimensional interconnected network structure composed of relatively uniform nanoparticles, and high light transmittance. Here we review the recent progress in TiO2 aerogels for photocatalysis, focusing on preparation techniques, the crystalline phases’ influence on photocatalytic properties, the modification of photocatalytic properties, and the analysis and discussion of future development. In particular, we first summarize various preparation techniques, including sol–gel method, nanoparticles self-assembly synthesis, and high-temperature aerosol technique, then detail the structure and composition of TiO2 crystalline phases that affect the photocatalytic properties. Subsequently, we discuss strategies to further enhance the photocatalytic properties of TiO2 aerogels by the composite of SiO2 aerogel semiconductors, the doping of metal dopants, and the doping or composite of non-metallic substances, and elaborate the modification mechanism and the modification effect achieved. Finally, combined with the research status of TiO2 aerogels and the development experience of other aerogels, we conduct a reasonable analysis and discussion on their further research directions and industrialization roads.

The inherent low ionic conductivity of PVDF‐based electrolytes at room temperature and lithium dendrite penetration hinder its further application. Herein, a LaF3 doped Poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐ctfe)) quasi‐solid electrolyte is developed. High‐flux channels are created due to the optimization of the lithium environment that lanthanum preferentially competes coordination with anionic species for relaxing lithium hopping. Lithium carriers are therefore highly free and unbound at the molecular level, resulting in a high ionic conductivity (σ) of 0.7 mS cm−1 and a transfer number (tLi+) of 0.79 at 25 °C. Moreover, the in situ organic–inorganic LiF‐rich dielectric layer effectively improves the stability and compatibility of the electrode/electrolyte interface, ensuring interfacial lithium conduction while facilitating stable Li+ plating/stripping. As a result, the optimized Li/ATCSE‐3%/Li can deliver favorable compatibility at 0.1 and 0.3 mA cm−2 for stable Li+ plating/stripping for 2000 and 1200 h, respectively. The high‐mass loading (6.4 mg cm−2) pouch cell delivers a stable cycling performance over 100 cycles with a capacity retention of 85.8% at 0.3 °C. This work is anticipated to provide considerable insight into the creative design of lithium transport of polymer‐based for practical quasi‐solid‐state lithium metal batteries. [ABSTRACT FROM AUTHOR]

For lithium‐sulfur batteries (Li‐S batteries), a high‐content electrolyte typically can exacerbate the shuttle effect, while a lean electrolyte may lead to decreased Li‐ion conductivity and reduced catalytic conversion efficiency, so achieving an appropriate electrolyte‐to‐sulfur ratio (E/S ratio) is essential for improving the battery cycling efficiency. A quasi‐solid electrolyte (COF‐SH@PVDF‐HFP) with strong adsorption and high catalytic conversion was constructed for in situ covalent organic framework (COF) growth on highly polarized polyvinylidene fluoride‐hexafluoropropylene (PVDF‐HFP) fibers. COF‐SH@PVDF‐HFP enables efficient Li‐ion conductivity with low‐content liquid electrolyte and effectively suppresses the shuttle effect. The results based on in situ Fourier‐transform infrared, in situ Raman, UV–Vis, X‐ray photoelectron, and density functional theory calculations confirmed the high catalytic conversion of COF‐SH layer containing sulfhydryl and imine groups for the lithium polysulfides. Lithium plating/stripping tests based on Li/COF‐SH@PVDF‐HFP/Li show excellent lithium compatibility (5 mAh cm−2 for 1400 h). The assembled Li‐S battery exhibits excellent rate (2 C 688.7 mAh g−1) and cycle performance (at 2 C of 568.8 mAh g−1 with a capacity retention of 77.3% after 800 cycles). This is the first report to improve the cycling stability of quasi‐solid‐state Li‐S batteries by reducing both the E/S ratio and the designing strategy of sulfhydryl‐functionalized COF for quasi‐solid electrolytes. This process opens up the possibility of the high performance of solid‐state Li‐S batteries. [ABSTRACT FROM AUTHOR]

Conventional SiO2 aerogels composed of 0-dimensional nanoparticles do not have large-scale compression, tensile, and shear deformation capabilities, and the poor mechanical properties hinder their further development and application. We report a scalable strategy to construct the nanoporous network of a SiO2 aerogel by alternately linking octa-(aminophenyl)-T8-POSS and hexaphthalic acid. The resulting SiO2 aerogel exhibits high strengths (compression, tensile and shear strengths are 26.4, 9.16, and 8.31 MPa, respectively), excellent deformabilities (fracture compression, tensile, and shear strains are 82.63%, 57.81% and 108.02%, respectively), flexbile processability and good structural stability (only 1.7% plastic deformation occurs after 100 load–unload cycles at a large compression strain of 70%). Also, the mesoporous interconnected nanoskeleton with high porosity and the composition of fully hydrophobic groups also give the aerogel low thermal conductivities (0.02854 W/(m K) at 25 °C and 0.04638 W/(m K) at 300 °C) and superhydrophobic properties (hydrophobic angle 160° and saturated mass moisture absorption rate about 0.375%). The combination of these excellent properties ensures that the aerogel can be used as an efficient thermal insulation material for extreme environments, such as those where comprehensive mechanical and hydrophobic properties are strictly required. [ABSTRACT FROM AUTHOR]

Transparent conductive oxide (TCO) film acts as the window layer and carrier transport layer of silicon heterojunction (SHJ) solar cells. The optoelectrical and contact properties of TCO films, as well as the sputtering damage, limit the further efficiency improvement. Herein, the microstructure, morphology, and optoelectrical properties of sputtering‐prepared zinc‐doped indium oxide (IZO) are analyzed. The substrate temperature has a significant impact on the film growth and the cell performance. The IZO film is amorphous when substrate temperature is below 200 °C, while it seems the emergence of nanocrystals with the increased temperature, resulting in the highest conductivity (3070 S cm−1) and carrier mobility (47.9 cm2 V−1 s−1). In addition, the low carrier concentration and surface potential of IZO promote less optical parasitic absorption and higher work function. The IZO films are applied as the contact layer of SHJ solar cells. An impressive efficiency of 24.02% on an M2‐sized wafer is achieved, indicating great potential for the mass production application after careful optimization. [ABSTRACT FROM AUTHOR]

Spinel Li4Mn5O12 was successfully prepared by the wet chemical method to modify the surface of Li1.2Ni0.2Mn0.6O2. The results showed that an ultrathin spinel Li4Mn5O12 surface-modified layer with a thickness of approximately 10 nm was successfully constructed on the raw material surface, and that the cationic order was improved. In addition, the lithium ion diffusion coefficients (DLi+) of the raw materials and the modified materials were calculated using the EIS test and impedance fitting. The results indicated that the ultrathin Li4Mn5O12 surface modification shell can increase the lithium ion diffusion rate of the material and improve the rate capability of the material. So, the surface modification layer of spinel Li4Mn5O12 can reduce the oxygen loss of the first cycle and improve the cationic order of the material. Therefore, the first coulombic efficiency of Li4Mn5O12/Li1.2Ni0.2Mn0.6O2 material at the current density of 12.5 mA·g−1 reaches 80.46%, and the capacity retention rate reaches 91.74% after 50 cycles, which are 3.36% and 21.23% higher than those of the raw materials, respectively. It showed better electrochemical reversibility and cyclic stability. This study provides a straightforward and convenient modification method for improving the stability of cobalt-free lithium-rich manganese cathode materials and has a favorable application prospect. [ABSTRACT FROM AUTHOR]

The structural integrity and continuity are prerequisites for exploiting the performance advantages of aerogels, while limitations in mechanical properties, such as low strength, high brittleness, and poor processability confine fully intact aerogels to laboratory settings. Here, a composite aerogel SPCCAM designed with hierarchical structuring into 1D building blocks at the nanoscale and honeycomb‐like anisotropic architecture at the microscale is presented. The inner carboxylated cellulose nanofiber core (CNFs‐C) exhibits much higher strength than the intermediate polybenzoxazine (PBOZ) shell, and the interface is highly reinforced by a crosslinked network of amino and hydrogen bonds, forming a highly stable 1D building block. Superhydrophobic SiO2 nanoparticle (hydrophobic‐260) is discretely distributed on the outer surface of the PBOZ shell, resulting in a nanoscale lotus leaf effect. Thus, the SPCCAM demonstrates outstanding properties including ultrahigh strength, excellent deformability and fatigue resistance, good machinability, ultralow thermal conductivity and coefficient of linear expansion, and superhydrophobicity from the inside out and long‐term hydrophobic stability along the radial direction of microscale channels, defining a novel method for designing aerogels with superior integrated mechanical, thermal insulation, and hydrophobic properties, and offering an attractive solution for high‐efficiency thermal insulators in high‐moisture extreme environments, such as deep‐sea and polar regions. [ABSTRACT FROM AUTHOR]