Synergistic oxygen vacancies generation and Fermi level modulation in Cd-doped SnO₂ nanofibers for effective...

Triethylamine (TEA) endangers both the environment and public health due to its high toxicity and carcinogenic potential, underscoring the urgent need for effective detection technologies. However, metal oxide semiconductor sensors for TEA detection generally suffer from limitations such as sluggish response and recovery speed, limited selectivity, poor humidity resistance, and ambiguous sensing mechanisms, restricting their practical applications. Herein, SnO₂ nanofibers doped with different Cd contents were fabricated via electrospinning and calcination technologies for TEA detection. Among them, the sensor with a Cd content of 3.65 at% exhibited the highest response (R_a/R_g ≈ 32.0@100 ppm TEA), ultra-short response time (3 s), good selectivity, and excellent moisture resistance at 180 °C. The enhanced performance arises from heterovalent Cd doping, which regulates the Fermi level and oxygen vacancies of SnO₂, thereby optimizing surface chemisorbed oxygen and enhancing charge transfer efficiency, significantly promoting the gas-sensing reaction. Further, density functional theory (DFT) calculations revealed the interfacial interactions, charge density distributions, and surface adsorption energies between oxygen vacancies and TEA, enabling atomic-scale analysis of the sensing mechanism in Cd-doped SnO₂ toward TEA molecules. This work demonstrates Cd-doped SnO₂ sensors' significant application potential in environmental monitoring and industrial safety systems.