Polyoxometalates/metal–organic frameworks-derived ZnO/ZnWO4 nanoparticles for highly sensitive and selective ppb-level NO2 detection

Herein, an investigation on polyoxometalate/MOFs-derived gas sensing materials was reported. In this work, we used silicotungstic acid (SiW₁₂)/ZIF-8 as precursors to in-situ derive ZnO/ZnWO₄ nanoparticles, which show high gas sensing sensitivity of 26.392 to 1 ppm NO₂ gas at the operating temperature of 140 °C, 7.26 times than MOF-derived pure ZnO without ZnWO₄. Compared with other gases (ethanol, acetone, toluene, formaldehyde, ammonia), the fabricated gas sensor exhibits excellent selectivity for NO₂. In addition, the repeatability is excellent in 6 times test, and the response is stable in 30 days. Sensing mechanism was also comprehensively explored. The improvement of gas sensing performance is attributed to the formation of p-n heterojunction, and the electrons are transferred from ZnO to ZnWO₄, which improves the scientific problem of high carrier recombination rate of ZnO. This study introduces a method for preparing derivatives based on POM/MOFs, and applying them to the field of gas sensing. It provides a new reference for the application of polyoxometalates in the field of gas sensing.