As an essential part of solid-state lithium-ion batteries, solid electrolytes are receiving increasing interest. Among all solid electrolytes, garnet-type Li₇La₃Zr₂O₁₂ (LLZO) has proven to be one of the most promising electrolytes because of its high ionic conductivity at room temperature, low activation energy, good chemical and electrochemical stability, and wide potential window. Since the first report of LLZO, extensive research has been done in both experimental investigations and theoretical simulations aiming to improve its performance and make LLZO a feasible solid electrolyte. These include developing different methods for the synthesis of LLZO, using different crucibles and different sintering temperatures to stabilize the crystal structure, and adopting different methods of cation doping to achieve more stable LLZO with a higher ionic conductivity and lower activation energy. It also includes intensive efforts made to reveal the mechanism of Li ion movement and understand its determination of the ionic conductivity of the material through molecular dynamic simulations. Nonetheless, more insightful study is expected in order to obtain LLZO with a higher ionic conductivity at room temperature and further improve chemical and electrochemical stability, while optimal multiple doping is thought to be a feasible and promising route. This review summarizes recent progress in the investigations of crystal structure and preparation of LLZO, and the impacts of doping on the lithium ionic conductivity of LLZO.

MXenes have been under a lot of scientific investigation due to the novel characteristics that are inherent to two-dimensional nanostructures. There are a multitude of MXenes being studied and one of the most popular among these would be the titanium carbides. The general formula for titanium carbide is Ti _{n+ 1}C _n for the nanosheets produced that have undergone much study in the past few years. These studies include how the etching process affects the final MXene sheet and how the post-processing via heat or combining with polymers and/or inorganic compounds influences the mechanical and electrical properties. It is found that different etching techniques can be used to change the electrical properties of the produced MXenes and different post-processing techniques can be used to further change the properties of the nanosheets. The possible application of the titanium carbide MXenes as chemical sensing and energy storage materials will be briefly discussed. MXene nanosheets show promise in such devices due to their high surface area to volume ratio and their specific surface structure with feasible surface functionalization.

Electrodeposition, which features low cost, easy scale-up, good control in the composition and great flexible substrate compatibility, is a favorable technique for producing thin films. This paper reviews the use of the electrodeposition technique for the fabrication of several representative chalcogenides that have been widely used in photovoltaic devices. The review focuses on narrating the mechanisms for the formation of films and the key factors that affect the morphology, composition, crystal structure and electric and photovoltaic properties of the films. The review ends with a remark section addressing some of the key issues in the electrodeposition method towards creating high quality chalcogenide films.

Thin films of TiO₂(B) nanowires are known to have sensitive and fast response to vapors of nitro-explosives under ambient conditions. The sensing response is believed to be affected by the humidity of ambient air that changes the density of hydroxyl groups on the TiO₂(B) surfaces. To verify this mechanism, the role of surface hydroxyl groups on TiO₂(B) nanowires was investigated via various surface modifications. It was found that a higher density of surface hydroxyl groups will constantly enhance the chemiresistive response of TiO₂(B) nanowires to the nitro-explosives vapors. These surface hydroxyl groups serve as a pathway for effective charge transfer between the nitro groups on the explosive molecules and the TiO₂(B). The evidence of charge transfer complex formation between nitro groups and titanium dioxide is also confirmed by Fourier transform infrared spectroscopy.

Acetone existing in human breath is an effective biomarker of diabetes which can be used for the early diagnosis and daily monitoring the health status of diabetes (in particular, type 1 diabetes). Comparing to other conventional methods for diabetes diagnosis and monitoring based on analyzing blood glucose level, breath analysis of acetone is a method with merits such as non-invasive, accurate, convenient, and inexpensive. A novel nanostructured K2W7O22 was recently developed and tested on its feasibility for acetone detection. The results show that K2W7O22 can effectively detect trace amount of acetone at room temperature. The lowest detection limit ~ 2.0 ppm (parts per million) with a fast response time of 12 s is achieved. Further improvement of sensing performance with detection limit down to 25 ppb (parts per billion) of acetone can be achieved through optimizing the material properties of K2W7O22 and modifying the design of device circuit to realize weak signal detection. The excellent acetone response is studied due to unique properties of K2W7O22, ferroelectric and semiconducting, which result in the effective interaction and strong charge transfer between acetone and K2W7O22. This study can improve the understanding of the new material and its sensing mechanism, and thus give ideas for further increasing the sensitivity for acetone detection, eventually resulting in an advanced material capable of analyzing acetone in exhaled breath for disease diagnosis and monitoring purpose.