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Hazardous gases have been strongly associated with being a detriment to human life within the environment. The development of a reliable gas sensor with high response and selectivity is of great significance for detecting different hazardous gases. TiO2 nanomaterials are promising candidates with great potential and excellent performance in gas sensor applications, such as hydrogen, acetone, ammonia, and ethanol detection. This review begins with a detailed discussion of the different dimensional morphologies of TiO2, which affect the gas sensing performance of TiO2 sensors. The diverse morphologies of TiO2 can easily be tuned by regulating the manufacturing conditions. Meanwhile, they exhibit unique characteristics for detecting gases, including large specific surface area, superior electron transport rates, extraordinary permeability, and active reaction sites, which offer new opportunities to improve the gas sensing properties. In addition, a variety of efforts have been made to functional TiO2 nanomaterials to further enhance sensing properties, including TiO2-based composites and light-assisted gas sensors. The enhanced gas sensing mechanisms of multi-component composite nanomaterials based on TiO2 include loaded noble metals, doped elements, constructed heterojunctions, and compounded with other functional materials. Finally, several studies have been summarized to demonstrate the comparative sensing properties of TiO2-based gas sensors.

Aqueous zinc-ion batteries (ZIBs) is a potential energy storage system due to its advantages of low cost, good safety, and high theoretical capacity (820 mAh g

Hydrogen generation efficiency and stability of the photoelectrocatalytic (PEC) water splitting relate closely to the crystallinity and the interface structure of the photoanodes. Here we demonstrated a feasible strategy for improving the cystallinity and interface quality of the ZnO/CdS nanoheterojunction arrays (NHAs) via CdCl2-assisting post-treatment. CdCl2 treatment was found to promote the recrystallization and densification of the CdS shell layer, the formation of the ZnxCd1-xS intermediate layer between ZnO and CdS, and the creation of an intermediate band (IB) in the forbidden band of CdS due to the high-density ClS states. Meanwhile, the annealing temperature was also lowered from 550 °C to 430 °C with the assistance of CdCl2 treatment. These improvements facilitate the seperation and transport of the photogenerated carriers and extends the light absorption range, resulting in extremely enhanced photocatalytic current and stability. Consequently, the photocatalytic currency reaches to 22 mA cm−2 under the 100 mW cm−2 illumination with the xenon lamp (λ > 420 nm), which is nearly two times larger than that annealed solely at 550 °C but without CdCl2 treatment. The photocatalytic current remains 92% of the initial value after 20-h photocatalytic test.

Aqueous zinc-ion batteries (ZIBs) is a potential energy storage system due to its advantages of low cost, good safety, and high theoretical capacity (820 mAh g−1). However, the lack of cathode materials with long cycle stability severely restricts the development of ZIBs. In this paper, V2O5/ NaV6O15 nanocomposites are synthesized by molten salt method in one step and used as cathode material for ZIBs, which have good electrochemical performances. The specific capacity of the materials remain 160 mAh g−1 when the current density is 0.5 A g−1 after 1000 cycles, and the capacity retention rate is 102.03% when the current density is 5 A g−1 for 1000 cycles. This is mainly due to the large number of active sites generated by crystal defects and the synergistic interaction between the dual-phase materials, which reduces the stress of ions inserted/extracted during the Zn2+ storage process and improves the electrochemical performance.