Nanostructure modulation of Co3O4 films by varying anion sources for pseudocapacitor applications

Abstract

We controllable designed and synthesized four kinds of three-dimensional (3D) hierarchical nanostructured Co3O4 thin films directly deposited on the nickel foam surface by a facile chemical bath deposition method. The morphologies of the Co3O4 films were regulated by using different anions (SO42−, NO3−, Cl−, and CH3COO−) originated from the precursors. The effect of different anions on the surface morphologies and pseudocapacitance behaviors of Co3O4 films was investigated by multiple electrochemical methods, including cyclic voltammetry (CV), galvanostatic charge-discharge cycles (GCD) and electrochemical impedance spectroscopies (EIS). The results indicated that the anions in the precursor salts greatly affected the morphology and porosity of the Co3O4 thin film, and consequently exhibited the different electrochemical performances in 2.0 M KOH electrolyte. The Co3O4 thin film prepared from cobalt acetate shown excellent electrochemical performance among the four different Co3O4 thin films electrodes, such as a high specific capacitance (743.8 F·g−1) and nice cycling stability (95.8% retention after 1000 charge-discharges at a high current density of 5 A·g−1). Furthermore, this work also provides a facile large-scale fabrication method to prepare secondary nanostructure on pseudocapacitance materials, such as graphene, transition metal oxides, carbon fibers, for enhancing the electrochemical performance of supercapacitor at low operation temperature.