Synthesis, structural and optical study of Ni-doped Metal-organic framework for adsorption based chemical sensor application

Abstract

Metal-Organic Framework (MOF) is a highly crystalline 3D material where metal ions and polydentate organic linkers are joined to form a highly stable mesoporous network. Its meritorious applications (like catalysis, gas storage, adsorption etc.) has motivated the researchers to work toward chemical sensor devices. In this work, synthesis of transition metal Zn/Ni nitrates and terephthalic acid (BDC) as a precursor dissolved in dimethylformamide (DMF) by solvothermal technique is reported. The prepared MOF samples consist of Zn4O acting as a secondary building unit, which are coordinated to BDC, a bidentate ligand dissolved individually in DMF to form a 3D structure. The excess of water molecules were removed using diethanol-amine (DEA), while the reaction energy was provided by citric acid. X-ray diffraction (XRD) pattern revealed the crystalline nature of as-synthesized and Ni-doped MOF-5 samples. XRD studies further tells about the variation in crystallite size in Ni-doped MOF-5. Surface morphology revealed the well-ordered structure with a large number of pores in mesoscale. The nucleation and growth mechanism is generalised for the formation of these nanostructure. Photoluminescence measurements have unveiled the luminescent nature of the synthesized MOF, which is vital for chemical sensor applications. Device application of the MOF samples as an adsorbent based chemical sensor is proposed with the sensing mechanism for NO2 gas.