Rationally designed trimetallic Prussian blue analogues on LDH/Ni foam for high performance supercapacitors

Abstract

Rational design of a Prussian blue analogue (PBA)@Ni–Co layered double hydroxide (NiCo-LDH) nanocomposite electrode material is vitally important for synthesizing high-performance supercapacitor electrodes. In this work, such nanocomposite electrode materials were successfully fabricated by a facile hydrothermal method. Firstly, three-dimensional (3D) regulated NiCo-LDH nanosheets with high interlayer space were grown on nickel foam under mild synthetic conditions. Then these nanosheets as a precursor were in situ converted into the target PBA@NiCo-LDH/NF nanocomposite electrode by a facile thermal ion-exchange reaction with potassium ferricyanide (K₃[Fe(CN)₆]). A series of PBA@NiCo-LDH/NF nanocomposite electrodes were fabricated with different ratios of Ni and Co and reaction temperatures. Their structures and morphologies were characterized by X-ray diffraction (XRD), FT-IR and scanning electron microscopy (SEM). Electrochemical investigation reveals that the PBA@Ni_0.4Co_0.6-LDH electrode exhibits the best electrochemical performance with an area specific capacitance of 2004.26 mF cm⁻² at 1 mA cm⁻², which is much higher (about three times) than the properties of each single component. All results demonstrate that (1) high-performance composite electrodes can be effectively fabricated and (2) fabrication of such composites is highly necessary and important.