Abstract
The sensitivity of chemiresistive sensors is inherently compromised by ambient humidity and trace level detection of toxic gases has potential challenges at room temperature. Herein, we designed a metal-organic framework (MOF) on a layered MXene hybrid by tagging a ZIF-67-based MOF on layered Ti3C2Tx MXene and following this with a surface ligand exchange process to design a highly sensitive, humidity tolerant chemiresistive sensor for ultra-low ppb level (200 ppb) NH3 sensing. The gas selectivity of MXenes was influenced by surface tagging with the MOF, which creates high surface-active features that promote the interaction and selectivity of NH3 on the MXene surface. In addition, a passive shell ligand exchange reaction provides not only a hydrophobic surface and environmental stability to the hybridized surface but also contributes to the sensing performances. The hybridized H-MOF/MXene-based sensor exhibited a superior NH3 sensing response (ΔR/Rg = 6.9, 1 ppm) at room temperature with high selectivity and reliability and a theoretical detection limit of 12.8 ppb. Passive ligand exchange had a significant effect on the sensing response at room temperature but improved humidity resistance and long-term durability. The H-MOF/MXene response to NH3 was only reduced by 0.22% and 0.27% at relative humidities of 76% and 93%, which represented 1.2 and 8.3-fold improvements in the sensing response versus MOF6/MXene and bare MXene at an NH3 concentration of 10 ppm. Furthermore, the sensing mechanism involved electronic interactions and charge transfer through a Schottky junction between the MOF and MXenes and the synergistic promotion of the sensing response on the hybridized H-MOF/MXene platform. This work provides a means of designing a surface functionalized MOF on MXene heterostructures that enables the production of sensors tailored to diverse environmental conditions.
Original language | English |
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Pages (from-to) | 26132-26146 |
Number of pages | 15 |
Journal | Journal of Materials Chemistry A |
Volume | 12 |
Issue number | 38 |
DOIs | |
State | Published - 29 Aug 2024 |