Pt nanoparticle-functionalized Fe2(MoO4)3 hollow microspheres for parts-per-billion NO2 sensors operated at 80 °C

Conductometric NO2 sensors with easy preparation, low operating temperature, ultralow limits of detection, high response, and long-term stability are highly required. In pursuing this concept, the Pt nanoparticle-functionalized Fe2(MoO4)3 hollow microsphere sensors were designed based on the synergistic effect of noble metal additives and a non-agglomerated hierarchical structure. Herein, a promising NO2 gas sensor with high sensitivity at 80 °C and good long-term stability was designed and prepared by a modified facile impregnation method, which is free of reductants, surfactants, and stabilizers. The 5 wt% Pt functionalized Fe2(MoO4)3 shows superior sensing performance over pristine Fe2(MoO4)3, including a 100 °C decrease in optimal operating temperature, 19 times increase in gas response, and realized an ultralow parts-per-billion level detection of limit, as well as good selectivity and reproducibility. The synergistic effect was validated by comparing the sensing performance with Pt-decorated non-agglomerated hollow microspheres and agglomerated nanoparticles.