Facile synthesis of nickel-based bimetallic metalorganic frameworks with different cobalt ratios as electrode material for electrochemical supercapacitors

Bimetallic based metal organic frameworks (MOFs) are one of the prominent candidates for technological important energy storage and conversion devices owing to their enhanced conductivity and stability. In this work, nickel-based bimetallic metal-organic frameworks were efficiently synthesized by a facile hydrothermal method, and cobalt metal ions were incorporated in different molar ratios into the frameworks. Influence of cobalt metal ion incorporation on the electrochemical performance was investigated. Significantly, partial substitution of cobalt metal ion into the framework favorably enhances the supercapacitor performance of the nickel-based bimetallic MOFs. The optimized nickel-based bimetallic MOFs with nickel and cobalt molar ratio of 1:1 exhibit a large specific capacitance of 3305 F/g at a current density of 2 A/g, with the lowest electrochemical internal resistance. Further studies disclose that the supercapacitor performance enhancement can be ascribed to the combined effect of synergistic interactions between two metal ions and the hierarchical microsphere structure in MOFs. This investigation result affords a better understanding in the fabrication of homogeneous bimetallic based MOFs electrode material for next-generation energy conversion and storage devices.