Novel triethylamine sensor with low operating temperature and low detect limit using the nano n-p heterojunction of δ-MnO₂ and WO₃

Developing triethylamine (TEA) sensors using metal oxide semiconductors (MOS) presents challenges such as achieving high sensitivity, low operating temperatures, and reliable detection of trace TEA. In this study, a novel two-step solvothermal synthesis strategy was developed for the sequential fabrication of δ-MnO₂ nanosheets and δ-MnO₂/WO₃ (WMn) heterojunction composites. The resulting WMn heterostructure features a unique morphology, where δ-MnO₂ nanosheets are encapsulated within a WO₃ matrix, forming well-defined layered interfaces and abundant active sites. This tailored structure significantly enhances the TEA sensing performance. In particularly, WMn1 sensor achieves an ultrahigh response of 515.37–20 ppm TEA at 140 °C. The sensor also exhibits an exceptionally low detection limit of 15.91 ppb, along with rapid response/recovery kinetics and long-term stability. The superior performance is attributed to the formation of n–p heterojunction and the synergistic effects of electronic and chemical sensitization, which optimize charge carrier dynamics, reduce interfacial resistance, and enhance surface reactivity. By focusing on interface engineering in heterojunction-based gas sensors, this study contributes to the strategic design of high-performance sensing materials, with potential applications in environmental monitoring and industrial safety.