A facile and scalable strategy for synthesis of size-tunable NiCo2O4 with nanocoral-like architecture for high-performance supercapacitors

Abstract

There is a great need to develop high-performance electroactive materials for supercapacitors. The study reported a facile and scalable strategy for synthesis of size-tunable NiCo2O4 with nanocoral-like architecture. Cobalt nitrate and nickel nitrate were dissolved in a tertbutanol solution and heated to reflux state under microwave radiation. The amounts of ammonia was dropped into the mixed solution to form nickel/cobalt double hydroxides. The reaction can complete within 15min with the productivity of 99.9%. The obtained double hydroxides display flowercluster-like ultrathin nanostructure. The double hydroxide was calcined into different NiCo2O4 products using different calcination temperature, including 400°C, 500°C, 600°C and 700°C. The resulting NiCo2O4 is of nanocoral-like architecture. Interestingly, the size of coral can be easily controlled by adjusting the temperature. The NiCo2O4 prepared at 400°C gives a minimum building block size (10.2nm) and maximum specific surface area (108.8 m2·g−1). The unique structure will greatly improve faradaic redox reaction and mass transfer, the NiCo2O4 electrode exhibits excellent electrochemical performances for supercapacitors. Its maximum specific capacitance was 870.7 F g−1 at the current density of 1A g−1. The specific capacitance can remain 805.8 F g−1 at the current density of 10 A g−1, which offers an increase of about 4.6% after 1500 cycles. Moreover, the study also provides prominent approach to fabricate various size-adjustable nano-materials with three-dimensional network framework for supercapacitors, Li-ion batteries and other energy storge devices.