Application of Ni/Co-based metal–organic frameworks (MOFs) as an advanced electrode material for supercapacitors

Abstract

A Ni/Co-based bimetallic metal–organic framework (Ni/Co–MOF) [CoNi(μ₃-tp)₂(μ₂-pyz)₂] (tp = terephthalic acid and pyz = pyrazine) was synthesized through a hydrothermal method. Structural characterization revealed that metal centers are equally occupied by Co²⁺ and Ni²⁺ ions. The supercapacitive behavior of the synthesized Ni/Co–MOF was evaluated using cyclic voltammetry (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) measurements in 3 M KOH as electrolyte. The Ni/Co–MOF exhibited an outstanding specific capacitance of 1049 F g⁻¹ at a discharge current density of 1 A g⁻¹, good rate capability (642 F g⁻¹ at 10 A g⁻¹), and 97.4% capacitance retention after 5000 cycles. To the best of our knowledge, this is the first bimetallic MOF that is used in supercapacitors and its encouraging properties indicate that Ni/Co–MOF can be a promising candidate as an advanced electrode material for supercapacitors.