Design of 3D flower-like NiWO4/WO3 heterostructures with excellent trimethylamine sensing performance†

The development of sensors with excellent and low detection limits is critical for detecting trimethylamine (TMA) in seafood safety monitoring and healthcare. Herein, WO₃ flower-like structures functionalized with NiWO₄ were fabricated using a combination of solvothermal and hydrothermal methods and subsequently utilized in gas sensors for TMA detection. The gas-sensing results demonstrated that the incorporation of NiWO₄ nanoparticles onto the WO₃ surface reduced the optimal operating temperature and further enhanced the selectivity and response to TMA. Representatively, the 10-NiWO₄/WO₃ sensor exhibited a sensing response of 12.05 to 10 ppm TMA, along with rapid response/recovery times (14/17 s), a low theoretical detection limit of 14.26 ppb, a wide detection range, and excellent long-term stability at 150 °C. These improved capabilities are primarily ascribed to the modulation of surface carrier concentration within the n–n heterojunction at the NiWO₄/WO₃ interface, coupled with the catalytic promotion effect of NiWO₄ on gas-sensing reactions, and the unique hierarchical flower-like structures. This study highlights the considerable potential of 3D flower-like NiWO₄/WO₃ heterostructures as a highly promising sensing material for TMA gas sensors.