Nano-Micro Structure of Metal Oxide Semiconductors for Triethylamine Sensors: ZnO and In₂O₃

Toxic and harmful gases, particularly volatile organic compounds like triethylamine, pose significant risks to human health and the environment. As a result, metal oxide semiconductor (MOS) sensors have been widely utilized in various fields, including medical diagnostics, environmental monitoring, food processing, and chemical production. Extensive research has been conducted worldwide to enhance the gas-sensing performance of MOS materials. However, traditional MOS materials suffer from limitations such as a small specific surface area and a low density of active sites, leading to poor gas sensing properties—characterized by low sensitivity and selectivity, high detection limits and operating temperatures, as well as long response and recovery times. To address these challenges in triethylamine detection, this paper reviews the synthesis of nano-microspheres, porous micro-octahedra, and hollow prism-like nanoflowers via chemical solution methods. The triethylamine sensing performance of MOS materials, such as ZnO and In₂O₃, can be significantly enhanced through nano-morphology control, electronic band engineering, and noble metal loading. Additionally, strategies, including elemental doping, oxygen vacancy modulation, and structural morphology optimization, have been employed to achieve ultra-high sensitivity in triethylamine detection. This review further explores the underlying mechanisms responsible for the improved gas sensitivity. Finally, perspectives on future research directions in triethylamine gas sensing are provided.