MIL-100(Fe) /ZnO nanocomposite sensors: An enhanced ammonia selectivity and low operating temperature

Abstract

This study aims to enhance the response and selectivity of zinc oxide (ZnO) gas sensors by its incorporating in MIL-100(Fe) as a support material. ZnO nanocomposites were synthesized by impregnating MIL-100 with varying weight percentages of zinc oxide (10% to 20%). The fabricated sensors underwent characterization through XRD, FTIR, DRS (UV-Vis), SEM/EDS, and NH3-TPD techniques to assess their material composition and sensor performance. DRS (UV-Vis) techniques revealed a significant decrease in the band gap, from Tauc analysis, accompanied by a 20% decrease in the Schottky barrier of the nanocomposite, compare to ZnO. Furthermore, the optimal operating temperature for the MIL-100/ZnO nanocomposites was identified as 240 °C, contrasting with pure ZnO sensors that exhibited an increasing response with temperature. Notably, the MIL-100/ZnO nanocomposites exhibited substantially improved selectivity for ammonia, displaying 3–6 times higher selectivity compared to pure ZnO sensors. Additionally, the response to ammonia increased threefold in the MIL-100/ZnO nanocomposites. This enhancement in selectivity and response can be attributed to the synergistic interaction between ammonia molecules and the Lewis acid sites present in the MIL-100 framework, facilitated by coordination bonds. The findings underscore the immense potential of MIL-100/ZnO nanocomposites as a promising solution for augmenting the selectivity of ZnO gas sensors. This work contributes valuable insights towards the advancement of gas sensing technology and paves the way for the development of highly selective gas sensors with extensive applications across various fields.