Enhanced Electrochemical Properties of Bimetallic-Organic Frameworks (BMOF) as Electrodes for Electrochemical Capacitor Applications

Bimetallic organic framework (BMOF) utilizing the combination of two metals sources of calcium (Ca) and nickel (Ni) with two organic ligands of 2,6-naphthalene dicarboxylic acid (NDC) and 2-methylimidazole (MIM) was synthesized using wet chemical precipitation method (Ca-Ni-BMOF) and tested as electrode materials for supercapacitor applications. By utilizing a beaker-type three-electrode configuration in a basic 1 M KOH electrolyte, the electrochemical study of Ca-Ni-BMOF was carried out where the sample with the metal precursors ratio of Ca:Ni=1:2 (mol/mol) achieved a specific capacitance of 125 F g
⁻¹
at a current density of 250 mA g
⁻¹
. Meanwhile, Ca-Ni-BMOF with the metal ratio of Ca:Ni=2:1 (mol/mol) achieved lower specific capacitance (12.76 F g
⁻¹
at 250 mA g
⁻¹
) compared to the single-metal Ca-MOF (19.75 F g
⁻¹
at 250 mA g
⁻¹
). This study highlighted the importance of utilizing a suitable amount of metal precursor ratio in BMOF, as incorporating different amounts of nickel into Ca-MOF could have both positive and negative impacts electrochemically.