Enhancing Gas Sensing Recyclability and Recovery Rate by Crystal Engineering of CuI Motif in MOFs

Abstract Metal-organic frameworks (MOFs) possess high sensitivity as chemiresistive gas sensing materials at room temperature (RT), while their applications are severely hampered by the issues of slow recovery and poor recyclability. To address these challenges, a strategy integrating DFT calculation with experimental synthesis has been developed to identify and remove non-essential active units with excessive interactions to gas molecules, thereby enhancing sensing recovery and recyclability. In a case study, DFT calculations revealed that one-dimensional (1D) {Cu4I3}n+ chains in a K-MOF, CuI-K-INA (HINA = isonicotinic acid), exhibit strong affinity to NO2 while 2D {Cu4I5}n- layers show moderate interactions. Thus, by modulating the structure features of CuI motifs in M-CuI-K-INA (M = Na+, K+, and Cs+, HINA = isonicotinic acid) type of MOFs, their NO2 sensing recovering and recycling performances were consequently optimized. Particularly, Cs-CuI-K-INA with solely 2D {Cu4I5}n- layers possesses the best sensing recovery and recycle abilities, meanwhile maintains the excellent sensitivity and selectivity among these RT NO2 sensing materials presented in the current study. This approach paves the way for chemiresistive sensing materials with improved recoveraibility and recyclability while retaining high sensitivity and selectivity.