Novel Cr and Sn co-doped Co3O4 polygon-based electrode material for supercapacitor application

Use of co-doped metal oxide-based materials for supercapacitor application is a novel approach to attain significantly enhanced capacitive properties. In this context, we are reporting here, the synthesis of Cr and Sn co-doped Co3O4 polygon-based material and its application in supercapacitor. The co-doped Co3O4 material was synthesized by varying the doping ratios of Cr and Sn as 3:7, 5:5 and 7:3 at.% respectively through hydrothermal synthesis route. Material and capacitive properties were studied for pristine and co-doped Co3O4 material. The crystalline structure, morphology and chemical composition were investigated by using XRD, SEM and EDX techniques, respectively. The XRD results revealed the formation of single cubic phase Co3O4 nanostructures with average crystallite size 40 nm. The SEM results explored the development of polygon-based nanostructures having sizes in the range of 40-50 nm. The EDX results exhibited the presence of only Co, Cr, Sn and O elements in the material thus proved the highly pure nature of this material. The electrochemical measurements were done with the help of CV, GCD and EIS techniques performed in a 3 M KOH electrolyte solution. The CV test revealed that, among the samples with doping ratios 3:7, 5:5 and 7:3 at.% of Cr and Sn in Co3O4 crystal lattice labeled as CrSnCo-1, CrSnCo-2 and CrSnCo-3, respectively, the CrSnCo-2 sample exhibited highest specific capacitance, i.e. 1413.56 Fg(-1) at 5 mVs(-1) and also showed excellent capacitance retention, i.e. 89.41% after 3000 CV cycles performed at a scan rate 5 mVs(-1). The GCD test showed the pseudocapacitive nature of the material with good stability, i.e. 77.38% (capacitance retention) at higher scan rate, i.e. 10 Ag-1. Moreover, the EIS spectroscopy revealed the excellent conductive nature of CrSnCo-2 material. These results suggest its potential application in energy storage devices like supercapacitors.