Exploration of the Gas Adsorption/Selection Behavior and Its Doping Regulation Strategy of COFs for Improved Gas-Sensing Performance
To understand the gas-sensing mechanism of COFs and explore an effective modulation way to regulate their sensing properties, the adsorption and sensing behaviors of NO<sub>2</sub>, NO, SO<sub>2</sub>, O<sub>2</sub>, H<sub>2</sub>O, CO<sub>2</...
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2025
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| Sammanfattning: | To understand the gas-sensing mechanism of COFs and explore an effective modulation way to regulate their sensing properties, the adsorption and sensing behaviors of NO<sub>2</sub>, NO, SO<sub>2</sub>, O<sub>2</sub>, H<sub>2</sub>O, CO<sub>2</sub>, H<sub>2</sub>S, CO, N<sub>2</sub>, and NH<sub>3</sub> gas molecules on the surface of pristine and n-doped (Na-adsorption) Tr-Th COFs are explored theoretically with first-principles calculations in this work. Attributed to the lowest unoccupied molecular orbital (LUMO) energy level of NO<sub>2</sub>, the adsorption of NO<sub>2</sub> on Tr-Th leads to a larger increase in carrier concentration increment (<i>n</i> = 1.79 × 10<sup>12</sup> to 6.26 × 10<sup>10</sup> cm<sup>–2</sup>) and a greater work function shift (ΔΦ = 0.178 eV) compared to other gases, which suggest that Tr-Th is a highly promising material for NO<sub>2</sub> sensing applications. n-Type doping elevates the Fermi level of COFs, resulting in a greater carrier concentration increment (<i>n</i> = 1.83 × 10<sup>12</sup> cm<sup>–2</sup> ∼ 2.52 × 10<sup>12</sup> cm<sup>–2</sup>) and a larger work function shift (ΔΦ = 0.08 eV ∼ 0.30 eV) upon exposure to NO<sub>2</sub>, NO, SO<sub>2</sub>, or O<sub>2</sub> compared to other gases. It means that apart from NO<sub>2</sub>, NO, SO<sub>2</sub>, and O<sub>2</sub> gases will also trap electrons in <i>n</i>-doped Tr-Th COFs, increase the electrical resistance dramatically, and then quench the source leakage current of the COFs-FET gas sensor. Our study provides more detailed information about the gas-sensing mechanism of COFs and highlights the key role that surface doping strategy plays in regulating the gas adsorption and selection behaviors for its practical gas sensor applications. |
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