Theoretical study of the gas sensing property of two-dimensional copper-hexahydroxybenzene frameworks

Two-dimensional (2D) metal-organic frameworks (MOFs) show considerable promise for gas sensing owing to their large surface area, great structural tunability, as well as abundant active sites. Here, we used first-principles calculations to studied the gas sensing properties of 2D Cu 3 (HHB) 2 film for several gases (NO, NO 2 , NH 3 , H 2 S, O 2 , and CO 2 ). The pristine Cu 3 (HHB) 2 film exhibits half-metallic property, with a metallic spin channel and a semiconducting spin channel. The results show that the Cu 3 (HHB) 2 film exhibits significant conductance responses to NO and NO 2 . Upon adsorption of NO and NO 2 , the conductance of the film increases from zero to 13.37 μS and 77.13 μS, respectively. This phenomenon can be attributed to the strong orbital hybridization between Cu 3 d orbitals and N/O 2 p orbitals, which introduces new electronic states near the Fermi level. While the adsorption of O 2 , CO 2 , NH 3 , and H 2 S preserves half-metallic property of Cu 3 (HHB) 2 , with only minor conductance changes. These findings demonstrate that the 2D Cu 3 (HHB) 2 film has high sensitivity and selectivity toward toxic NO and NO 2 gases, suggesting its potential as promising materials for NO or NO 2 gas sensors.