Electrodeposition of binderless Ni,Zn-MOF on porous nickel substrate for high-efficiency supercapacitors

Abstract

In this article, an indirect electrodeposition technique is applied for developing single- and bimetal-MOFs onto a porous nickel-foam (NF) support, which is found to have significant applications in a supercapacitor as binderless electrodes. In this regard, Ni-, Zn- and Ni,Zn-MOFs with different morphologies were deposited onto NF electrodes through indirect cathodic electrochemical deposition from terephthalic acid dissolved metal nitrate aqueous solutions. The prepared MOFs were analyzed using XRD, FT-IR, SEM and EDS analyzes. The structural analyses proved the formation of crystalline Ni-, Zn- and Ni,Zn-bdc MOFs onto nickel foam support. Electrochemical evaluations by charge-discharge tests revealed that the fabricated Ni-BDC/Ni foam, Zn-BDC/Ni foam and Ni,Zn-BDC/Ni foam electrodes are respectively capable of delivering specific capacitances of 536, 374, and 944 ​F ​g–1 at the applied current load of 2 ​A ​g–1. Furthermore, it is found that our fabricated samples exhibit capacitance retentions of 75.5%, 84.95% and 93.24% during 6000 cycling with the current density of 5 ​A ​g–1, respectively. The proper charge storage ability of the Ni,Zn-BDC/Ni foam electrode is attributed to its appropriate surface morphology, synergism effects and excellent physical contact as well as proper self-assembling onto the Ni foam.