Synthesis of precursor-derived 1D to 2D Co3O4 nanostructures and their pseudo capacitance behaviour

Abstract

Co₃O₄ nanochains and nanosheets consisting of small single crystalline particles have been obtained by controlling the morphology of the precursor Co(CO₃)_0.5(OH)·0.11H₂O via an environmentally friendly hydrothermal method without any addition of CO₃²⁻ sources. The nanochains were constructed of single crystal grains connected one by one to form a necklace structure. The size of the grains in the nanochains were adjusted through controlling the calcination of Co(CO₃)_0.5(OH)·0.11H₂O nanobelts at 350–600 °C. Porous Co₃O₄ nanobelts and irregular nanoparticles were created when the precursors were calcined at 300 and 700 °C, respectively. Through changing the volume ratios of ammonia to ethylene glycol in the solution, the morphology of the precursors was adjusted from one-dimensional (1D) nanobelts to a mixture of nanobelts and nanosheets and finally to 2D nanosheets. After calcination, the corresponding Co₃O₄ with a porous nanostructure was obtained. Importantly, when evaluated as electrode materials for supercapacitors, the as-prepared Co₃O₄ nanochains exhibit a superior supercapacitive performance with a capacitance of as high as 800 F g⁻¹ which is higher than that from most previous reports, which is possibly due to their special short range order and long range disorder structures as demonstrated by high-resolution transmission electron microscopy. In contrast, the capacitance of porous nanobelts and nanosheets is low compared with that of nanochains. Because of their improved performance, the as-prepared Co₃O₄ nanochains will be utilizable as electrode materials for supercapacitors.