Porous nickel cobaltite nanorods: desired morphology inherited from coordination precursors and improved supercapacitive properties

Abstract

A facile and general method for the synthesis of porous complex oxides is highly desirable owing to their significant applications for energy storage. In this contribution, the porous nickel cobaltite nanorods have been successfully prepared by thermal decomposition of organometallic compounds, using nitrilotriacetic acid (NTA) as a chelating agent to coordinate with the Ni and Co ions. The obtained precursors were demonstrated to be one-dimensional nanorods. The resultant porous nickel cobaltite nanorods basically preserved the morphology of the precursors. In addition, these nanoparticles show good crystallinity. The as-prepared nickel cobaltite displays nanorod-like morphology with about 1 μm length and about 100 nm diameter. With a large surface area of 103.4 m² g⁻¹, this novel material exhibited high specific capacitance of 1078 F g⁻¹ and 704 F g⁻¹ at current densities of 1 and 20 A g⁻¹, respectively. This suggests that about 65% of the capacitance is still retained when the charge–discharge rate is increased from 1 A g⁻¹ to 20 A g⁻¹. The specific capacitance retention is 94.4% after 2500 cycles, suggesting its excellent cycling stability. In addition, these porous nickel cobaltite nanorods may be useful in other fields such as Li-ion batteries and Li-O₂ batteries.