Hierarchical porous spindle-shaped MIL-88B@Fe2O3 with core-shelled structure for conductometric trimethylamine detection

Hierarchical porous spindle-shaped MIL-88B (HPS-MIL-88B) with core-shelled structure was prepared by citric acid-assisted. The material exhibits open channels on its outer surface and a hierarchical internal cavity structure with meso-/macro-pores. The samples were then pretreated at 200 °C to form an oxide film , aiming to improve the conductivity of material. The as-prepared HPS-MIL-88B-6 h@Fe 2 O 3 material with core-shelled structure exhibits superior selectivity and high sensitivity to trimethylamine (TMA) at 200 °C (detection limit as low as 1 ppm) with fast response and excellent repeatability. The outstanding sensing performance was owing to the open and hierarchical porous that enhances the reaction between the target gas and the active sites of the material. In addition, the metal unsaturated active sites of MIL-88B (Lewis’s acid) can selectively undergo acid-base reactions with TMA (Lewis’s base), enhancing the generation of oxygen species and improving the selective adsorption capacity towards the target gas. This work provides a new path route for the application of MOF materials in sensors.