Synergistic Self-Assembly Enabled Highly Ordered Mesoporous WSe₂/WO₃ Crystalline Heterostructures for Rapid NO₂ Sensing at Room Temperature

A rapid and highly sensitive detection of harmful gas molecules is crucial in artificial olfaction (electronic nose), which plays a significant role in areas such as environmental monitoring and healthcare. However, it remains a significant challenge to construct highly sensitive molecular sensors with fast response at room temperature due to the limitations in structures and properties (e.g., porosity, crystallinity, and carrier mobility) of the sensing materials. Herein, this study proposes a facile method to enable highly crystalline mesoporous WSe₂/WO₃ (m-WSe₂/WO₃) semiconductor heterostructures through controllable interfacial self-assembly of polyoxometalate (POM) clusters and amphiphilic block copolymers combined with a thermal-assisted conversion process. It allows uniform pore size, open channels, large specific surface area, highly crystalline framework, and abundant transition metal chalcogenide/metal oxide heterojunction interfaces. The m-WSe₂/WO₃-based chemiresistive semiconductor sensor achieves efficient detection of NO₂ at room temperature, including ultrafast response (5 s), high selectivity (<i>S</i>_NO2/<i>S</i>_gas > 5), high sensitivity (62.5%@50 ppm), low detection limit (50 ppb), and long-term stability (>30 days). Thanks to the synergistic improvement of sensing dynamics between mesostructure and heterojunction, such a few-second response time has been reduced by half of the reported values in most existing counterparts based on two-dimensional materials. Our work paves the way for the application of high-performance and cost-effective molecular sensors in artificial olfaction, electronic skins, and wearable integrated circuits at room temperature.