Improving Triethylamine-Sensing Performance of WO₃ Nanoplates through In Situ Heterojunction Construction

Surface engineering techniques can be used to develop high-performance gas sensing materials and advance the development of sensors. In this study, we improved the gas sensing performance of two-dimensional (2D) WO₃ nanoplates by combining surface Zn modification and the in situ formation of ZnWO₄/WO₃ heterojunctions. Introducing Zn atoms by surface modification can reconstruct the atomic surface of 2D WO₃ nanoplates, creating additional active sites. This allowed for the preparation of various types of ZnWO₄/WO₃ heterojunctions on the surface of the WO₃ nanoplates, which improved the selectivity and sensitivity to the target gas triethylamine. The sensor exhibited good gas sensing performance for triethylamine even at low operating temperatures and strongly resisted humidity changes. The ZnWO₄/WO₃ material we prepared demonstrated a nearly threefold improvement in the triethylamine (TEA) response, with a gas sensing responsivity of 40.75 for 10 ppm of TEA at 250 °C. The sensor based on ZnWO₄/WO₃ has a limit of detection (LOD) for TEA of 200 ppb in practical measurements (its theoretical LOD is even as low as 31 ppb). The method of growing ZnWO₄ on the surface of WO₃ nanoplates using surface modification techniques to form surface heterojunctions differs from ordinary composites. The results suggest that the in situ construction of surface heterojunctions using surface engineering strategies, such as in situ modifying, is a practical approach to enhance the gas sensing properties and resistance to the humidity changes of metal oxide materials.