Heterostructures of NiFe-MOF/PBAs with high-performance supercapacitors obtained by compounding Prussian blue analogues on bimetallic organic frames

Abstract

Metal organic framework (MOF) is considered as an excellent electrode material for supercapacitors due to its low cost and homogeneous nanostructure, but the drawbacks of single MOF, such as low specific capacity and stability, limit its development, so the design of bimetallic MOF structural composites is a challenging but favourable strategy for the development of supercapacitors. In this paper, NiFe-MOF/PBAs heterostructure, a bimetallic MOF material with a granular rod-like structure, is successfully prepared by using bimetallic MOF as a precursor and introducing [Co(CN)6]3− ions to further convert it into PBAs (Prussian blue analogs). Due to the special macroporous structure of PBAs, the composite combines the advantages of the two MOF materials, and the specific capacity is as high as 4270.19 C g−1 at 1 A g−1. The composite still has excellent electrochemical properties when assembled into devices. The specific capacity is 1996.01 C g−1 at 1 A g−1, the energy density reached 749.99 W h kg−1 at a power density of 415.85 W kg−1, and the decay rate is only 1.14 % after 20,000 cycles at 10 A g−1. These results indicate that the designed dual MOFs composite electrodes have good application prospects in the field of electrochemical energy storage.