Study of Electrochemical Behaviour of Binder-Free Nickel Metal-Organic Framework Derived by Benzene-1,3,5-Tricarboxylic Acid for Supercapacitor Electrode

In this work, the Metal-Organic Framework (MOF) is derived from the metal nickel (Ni) and organic linker benzene-1,3,5-tricarboxylic acid (H3BTC). H3BTC is used because it is inexpensive and BTC3- builds multi-dimensional frameworks with metal centers that facilitate three carboxylate groups.Ni-MOF has been synthesized using a one-step hydrothermal technique. The synthesized product has been examined structurally and optically using Thermogravimetric Analysis, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV-Vis spectroscopy. XRD and FTIR results suggest the formation pattern of Ni-MOF. The band gap value of Ni-MOF calculated by UV-Vis spectroscopy comes out to be 3 eV which confirms the creation of nanoparticles. Surface morphology is examined with the help of the Field Emission Scanning Electron Microscopy technique showing the spherical shape of nanoparticles. The specific surface area is calculated by using the Brunauer-Emmett-Teller technique and the calculated value is 35.405 m(2)g(-1). The electrochemical response of the synthesized product has been tested in 3 different alkali aqueous electrolytes (1 M LiOH, 1 M NaOH, and 1 M KOH) with the help of cyclic voltammetry (CV), galvanic charge-discharge (GCD) technique & electrochemical impedance spectroscopy (EIS) to achieve the most appropriate combination of electrode-electrolyte for improved electrochemical results. The prepared Ni-MOF shows the highest specific capacitance (573 F g(-1)) in 1 M KOH alkali electrolyte in comparison to 1 M LiOH (535 F g(-1)) & 1 M NaOH (308 F g(-1)) at the low scan rate value of 5 mV s(-1) which reveals that the compatibility of Ni-MOF synthesized electrode material with 1 M KOH aqueous solution. Also the Ni-MOF shows excellent cycling stability (similar to 154% capacitance retention after 1000 cycles) in 1 M KOH alkali aqueous solution. All the results explain that the synthesized Ni-MOF can give the best electrochemical performance with 1 M KOH and hence can be used as an effective material for the electrode of a supercapacitor.