Metal–organic framework-derived ZnMoO4 nanosheet arrays for advanced asymmetric supercapacitors

Abstract

A metal–organic framework (MOF)-derived ZnMoO4 nanosheets architecture is synthesized on Ni foam using a facile and rapid template-free microwave-assisted hydrothermal approach and subsequent calcination. Further characterizations show that this binder-free electrode is composed of ZnMoO4 nanosheet arrays and, therefore, exhibits an excellent electrochemical performance. The nanosheet array-assembled 3D-frameworks exhibit a maximum-specific capacitance of 1212 F g−1 at a current density of 1 A g−1, and a good rate capability with a capacitance of 523 F g−1 even at a high current density of 20 A g−1. Approximately, 93.5% of the maximum-specific capacity is retained, even after 5000 continuous charge–discharge cycles, which exceeds most of ZnMoO4 and ZnMoO4-based electrodes reported so far. A ZnMoO4@Ni foam//GA hybrid device exhibits a maximum-specific capacity of 89 F g−1 at a current density of 1 A g−1, along with a substantial specific energy of 31.8 W h kg−1 at a specific power of 920 W kg−1. These results confirmed that the MOF-derived binder-free ZnMoO4 nanosheet arrays are suitable positive electrode materials for hybrid supercapacitors. Our work demonstrates an improved step toward rational design of high-performance integrated electrodes for supercapacitors with a new vision for theoretical and practical applications.