Electrochemical grown Ni,Zn-MOF and its derived hydroxide as battery-type electrodes for supercapacitors

Abstract

Todays, metal-organic frameworks (MOFs) and their derived structures are extensively investigated as the novel electrode materials for supercapacitors applications due to their stable porous architectures and exceptionally large specific surface areas. In this study, bimetallic Ni,Zn-MOF is first synthesized onto Ni foam via a novel indirect cathodic electrodeposition method for the first time. The fabricated Ni,Zn-MOFs onto Ni foam was converted to corresponding bi-metal hydroxide@C/Ni foam through direct chemical treating with 6 M KOH solution. The obtained Ni,Zn-MOFs/NF and Ni2-xZnx (OH)2 @C/NF electrodes were characterized through XRD, FT-IR, FE-SEM, AFM and EDS analyses. The results confirmed deposition of well-defined crystalline porous sheet-like structures of Ni3-xZnx(BTC)2 onto Ni foam, where its derived hydroxide@C electrode also exhibited similar morphology. In three-electrode system, the prepared Ni,Zn-MOF/Ni foam exhibited the superior storage capacities of 356.1 mAh g–1 and 255.5 mAh g–1 and capacity retentions of 94.2% and 84.5% after 6000 cycles at 5 and 15 A g–1, respectively. On the other hand, Ni,Zn-MOF derived hydroxide-C/Ni foam presented the superior capacities of 545 mAh g–1 and 406 mAh g–1 as well as proper cycling stabilities of 91.8% and 78.3% after 6000 cycling at the applied loads of 5 and 15 A g–1, respectively. The fabricated Ni,Zn-hydroxide-C/NF//N-PG/NF ASC device can deliver an of 34.5 W h kg−1 at a power density of 624 W kg−1. Based on these findings, both of these fabricated battery-type electrodes are introduced as the promising candidates for use in energy storage devices.