Morphology-Controllable Synthesis of Cobalt Oxalates and Their Conversion to Mesoporous Co3O4 Nanostructures for Application in Supercapacitors

In this work, one-dimensional and layered parallel folding of cobalt oxalate nanostructures have been selectively prepared by a one-step, template-free, water-controlled precipitation approach by simply altering the solvents used at ambient temperature and pressure. Encouragingly, the feeding order of solutions played an extraordinary role in the synthesis of nanorods and nanowires. After Calcination in air, the as prepared cobalt oxalate nanostructures were converted to mesoporous Co3O4 nanostructures while their original frame structures were well maintained. The phase composition, morphology, and structure of the as obtained products were studied in detail Electrochemical properties of the Co3O4 electrodes were carried out using cyclic voltammetry (CV) and galvanostatic charge-discharge measurements by a three electrode system. The electrochemical experiments revealed that the layered parallel folding structure of mesoporous Co3O4 exhibited higher capacitance compared to that of the nanorods and nanowires. A maximum specific capacitance of 202.5 F g(-1) hi been obtained in 2 M KOH aqueous electrolyte at a current density of 1 A g(-1) with a voltage window from 0 to 0.40 V. Furthermore, the specific capacitance decay after 1000 continuous charge-discharge cycles was negligible, revealing the excellent stability of the electrode. These characteristics indicate that the mesoporous Co3O4 nanostructures are promising electrode materials fog supercapacitors.