Synthesis and characterization of Zn-based bimetallic microporous MOF composites for effective formaldehyde sensing at room temperature

In the present work, we fabricated 1:1 bimetallic ZnCu(NA); ZnCd(NA); and ZnCo(NA) metal organic frameworks (MOFs) using nicotinic acid (NA) as organic linker by solvothermal method. All the compounds were characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, X-ray photoelectron Spectroscopy (XPS), and scanning electron microscopy (SEM).The drop-casting method used to develop a chemiresistive sensor to sense Volatile Organic Compounds (VOCs) at room temperature. These bimetallic sensors exhibited excellent sensitivity and good linearity in detecting formaldehyde at 1 to 50 ppm range. The responses of all sensing materials towards formaldehyde gas at 50 ppm concentration are Cu(NA) 3.74, ZnCu(NA) 18.6, Cd(NA) 3.13, ZnCd(NA) 8.36 and ZnCo(NA) 28.3.The sensing times of Cu(NA), ZnCu(NA), Cd(NA), ZnCd(NA) and ZnCo(NA) are 17, 9, 15, 18 and 17 respectively. These results demonstrate the potential applications of bimetallic Zn/Cu, Zn/Cd, and Zn/Co MOFs for sensitive and specific formaldehyde detection at ambient temperature. These results show that ZnCo(NA) sensing material is an excellent selective sensor for formaldehyde sensing.