Effect of calcination temperature on structural, morphological and electrochemical properties of Sn doped Co3O4 nanorods

Tremendous attention has been devoted for the development of highly efficient and stable electrode materials for supercapacitor applications. In this study, Sn-doped Co3O4 nanorods were prepared via solvothermal process using PVP and oxalic acid as surfactants. The phase, morphology and composition of Sn-doped Co3O4 nanorods were examined by XRD and SEM/EDX techniques. The electrochemical properties were studied via cyclic voltammetry (CV), galvanostatic charging-discharging (GCD), electrochemical impedance spectroscopy (EIS) measurements. The CV results show that electrode based on 5 at. % Sn-doped Co3O4 (5Sn-doped Co3O4) nanorods delivered the highest specific capacitance (842.44 F/g) at 5 mV/s than that of the electrode based on pure Co3O4 (729.39 F/g). In order to further tune the performance of this electrode, the structure, morphology and electrochemical behavior of 5Sn-doped Co3O4 sample were optimized via variety of calcination temperatures ranging from 250 to 400 °C. Notably, the 5Sn-doped Co3O4 sample calcined at 350 °C exhibited higher electrochemical performance (specific capacitance ~913.10 F/g) than other samples calcined at low or high calcination temperatures. The CV curves of 5Sn-doped Co3O4/T-350 °C at scan rates of 5–35 mV/s also showed pseudocapacitor behavior and good electrochemical reversibility. Moreover, the prepared novel electrode material has also displayed good rate capability (71.77%) at current density of 1–10 A/g and long-term stability of 92.23% after 3000 cycles. These excellent electrochemical characteristics of 5Sn–Co3O4/T-350 °C nanorods verified that it will be highly suitable electrode material for supercapacitor applications.