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

•We reported a facile and scalable strategy for synthesis of size-tunable NiCo2O4 withnanocoral-lide architecture.•Combination of microwave and tertbutanol as medium creates ultrathin nickel/cobalt double hydroxide with flowerclusters.•The method is very simple, rapid and efficient, it can be used for large scale productionof nanomaterials.•The size of NiCo2O4 nanocorals is easy to be can be controlled by adjusting calcination temperature.•Unique structure enhances rates of electron transfer and mass transport, NiCo2O4shows high electrochemical performance.

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 15 min 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 (10.2 nm) 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.

Graphical abstractWe reported a facile and scalable strategy for synthesis of size-tunable NiCo2O4 with nanocoral-like architecture. The unique structure will improve faradaic redox reaction and mass transfer, NiCo2O4 offers excellent electrochemical performance for supercapacitors.Figure optionsDownload full-size imageDownload as PowerPoint slide