Electrosynthesis of highly porous NiO nanostructure through pulse cathodic electrochemical deposition: heat-treatment (PCED-HT) method with excellent supercapacitive performance

Abstract

A highly porous NiO nanostructure is prepared through a pulse cathodic electrochemical deposition/heat-treatment (PCED-HT) method. Based on the method first a hydroxide precursor was deposited from an additive-free 0.005 M Ni(NO3)2 through a pulse–base-electro-generation procedure. The pulsed deposition experiments were performed at ton = 1 s, toff = 1 s, ipeak = 50 mA cm−2, T = 80 °C and 30 min. The green hydroxide powder was then calcined at 500 °C for 3 h and to obtain a black oxide powder. The mechanisms for the deposition of the nickel hydroxide precursor during the PCED step, as well as that of the formation of the final oxide product during the HT step were studied. The structural and morphological properties of the product were evaluated through XRD, IR and SEM. The results revealed the precursor and the product to be porous β-nickel hydroxide and porous cubic crystalline nickel oxide nanostructures, respectively. The super-capacitive performance NiO-based electrode was evaluated by cyclic voltammetry and the galvanostatic charge–discharge techniques in 1 M KOH electrolyte. It was observed that the fabricated porous NiO electrode exhibits capacitive behavior of low ΔEp value of 32 mV and width potential window (ΔV = 0.8 V), and is capable to deliver high specific capacitance of 1056.4 F g−1 and capacity retention of 89.7% after 3000 GCD cycles at current load of 3 A g−1, and energy density and power density as high as 82.3 Wh/Kg and 0.60 W/g, respectively.