Tungsten-Doped Heterojunction-Based Flower-like Gas Sensors for Sensitive and Rapid Detection of Trimethylamine Traces

Highly sensitive and fast detection of trimethylamine (TMA) is essential for applications, such as food freshness evaluation and environmental monitoring. In this work, W-doped Fe2O3/NiO nanomaterials with a flower-like architecture were synthesized and systematically investigated for TMA sensing. Structural and surface analyses confirmed that W doping effectively reduced the crystalline size, increased the specific surface area, and introduced abundant oxygen vacancies, while maintaining a porous nanosheet morphology. The sensor exhibited outstanding performance toward TMA at 237.5 °C, with a high response of 62.7 (100 ppm), ultrafast response/recovery times (3/17 s), a low detection limit of 30 ppb, excellent selectivity against common interfering gases, strong repeatability, and stability over 30 days. Density functional theory calculations further revealed that W doping lowers the oxygen vacancy formation energy (from 5.36 to 4.74 eV) and enhances the adsorption energy for TMA (−4.11 eV), supporting the experimentally observed high selectivity.