Fabrication and characterization of a nanoporous NiO film with high specific energy and power via an electrochemical dealloying approach

Graphical abstract: The maximum values were 170 Wh kg−1 and 27.5 kW kg−1 for specific energy and power at the potential window of 1.1 V, respectively. As so far as we know, the values of specific energy and power were both the highest than that reported in literatures. - Highlights: • We developed a convenient approach to fabricate the three-dimensional nanoporous NiO film. • The nanoporous films contain irregular 3D interconnected nanosheets structure with open channels. • The film as supercapacitor electrode showed excellent specific capacitance values. • It is noticed that the nanoporous film exhibited high specific energy and high specific power. • The electrochemical electrode presented excellent cycling performance and low retention. - Abstract: A three-dimensional (3D) nanoporous NiO film was fabricated via a two-step process using an electrochemical route. This process included electrodeposition of the Ni/Zn alloy film and electrochemical dealloying using a direct-current power source. The scanning electron microscopy images suggest that the film has an irregular 3D interconnected nanosheet structure with open channels. The adsorption–desorption isotherms indicate that the as-prepared NiO film had a high specific surface area of 198 m g−1 and a narrow pore size distribution, with two peaks at 2.7 and 5.1 nm. The specific capacitance of the sample reached 1670 F g−1 at a discharge current density of 1 A g−1. In addition, the as-prepared nanoporous film exhibited high performance during a long-term cycling test. The maximum values for the specific energy and specific power at the 1.1 V potential window were 170 and 27.5 kW kg−1, respectively