Chemiresistive and chem-FET Sensor: π-d conjugated metal-organic framework for ultra-sensitive and selective carbon monoxide detection

Π-d conjugated conductive coordination polymers (CCP) are an emerging class of materials that constitutes MOFs unique properties such as porosity and stability with electrical charge transport properties. The structural diversity and tunability of MOFs allow its application in electronics and selective gas sensing. This report deals with a reliable synthesis of room temperature (28 °C) conductive π-d conjugated metal-organic framework composed of Zn metal node and 3,6,7,10,11-hexahydroxytriphenylene (HHTP) organic ligand and its application in chemiresistive and Chem-FET sensing modality. The nature of as-synthesized MOF multiparametrically tested by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Uv-visible spectroscopy, energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), Field emission scanning electron microscopy (FE-SEM), BET surface area analyzer, and current-voltage (I-V) characteristics for its structural, spectroscopic, elemental, morphological, surface and electrical properties respectively. Zinc-hexahydroxytriphenylene (Zn-HHTP) sensor was prepared on interdigitated electrodes on Si/SiO2 substrate, which was fabricated by photolithography process and tested for both chemiresistive and Chem-FET sensing modalities. Zn-HHTP sensor showed the highest selectivity, excellent sensitivity, stability, and fastest response among all reported carbon monoxide sensors in both modalities. Multivariate analysis was carried out using principal component analysis (PCA) which reveals high discriminating capability of Zn-HHTP sensor towards NH3, SO2 and CO.