Electrochemical deposition of layer-by-layer Ni/RGO/Ni(OH)₂ composite on steel gauze electrode for high-performance supercapacitor application

In this paper, layer-by-layer Ni/RGO/Ni(OH)₂ composite was synthesized on the steel gauze (SG) electrode via cathodic electrodeposition. Two electrodes system was selected for electrodeposition in the galvanostatic condition. Electrodeposition of the first layer of nickel was conducted in the electrochemical cell with an SG substrate as a cathode. This electrode was fixed between two parallel graphite anodes and electrodeposition was performed from a mixture of NiCl₂, NH₄Cl, and NaCl solution. Co-electrodeposition of the reduced graphene oxide (RGO) with Ni(OH)₂ (as the second layer) on the Ni layer formed in the first step, was carried out in the same way from a solution containing graphene oxide (GO) and Ni(NO₃)₂ and finally SG/Ni/RGO/Ni(OH)₂ electrode was prepared. XRD, FT-IR, BET, and SEM techniques were used for characterization of the composite. The results showed that the formation of high surface area layer by layer Ni/RGO/Ni(OH)₂ structure in which, Ni(OH)₂ is in beta form. For evaluation of the electrochemical performance of the prepared electrode, electrochemical techniques such as cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS) were used. The SG/Ni/RGO/Ni(OH)₂ electrode demonstrated high specific capacity (1430 C g⁻¹ at the scan rate of 5 mV s⁻¹) and excellent cycling ability (5.7% capacity decay at the current density of 50 A g⁻¹ after 3000 cycles).