Innovative SIFSIX-1-Cu-Based Microwave Sensor with Directionally Ordered Interconnected Nanochannels: Revolutionizing High-Performance SO2 Detection

SO₂ sensors generally face challenges such as gas corrosion, poor selectivity, competition from water molecules, and high recovery costs. Metal-organic frameworks (MOFs), which offer excellent chemical stability, structural diversity, and low-cost reactivation, have emerged as ideal candidates for sensing materials. However, MOFs typically exhibit poor conductivity, making them unsuitable for traditional gas detection devices. In order to solve this problem, in this study, SIFSIX-1-Cu with directionally ordered interconnected nanochannels was synthesized. By optimizing the synergistic effects of mass transfer, chemical recognition and pore-size sieving, the performance limitations of traditional adsorption materials have been overcome. Furthermore, by integrating SIFSIX-1-Cu with a microwave circuit, the microwave gas sensor (MGS) detects target gases by monitoring changes in the electromagnetic properties—such as dielectric constant or resonance frequency—of the sensing material induced by gas adsorption. The unique detection mechanism allows the MOFs to operate without the need for conductivity optimization, effectively preventing the loss of active sites during the material modification process. The results showed that SIFSIX-1-Cu microwave gas sensor has a low limit of detection of 8.9 ppb at room temperature, and can achieve high selectivity (selectivity coefficient SO₂/CO₂ > 11.87) detection of SO₂ in a wide concentration detection range of 10 ppb -1000 ppm. Meanwhile, the sensor also exhibits excellent moisture resistance and repeatability.