Ag doped Co3O4 nanoparticles for high-performance supercapacitor application

Abstract

Ag doped Co3O4 nanoparticles (NPs) were synthesized via a co-precipitation method changing the concentration of Ag. The crystal structure, morphology, surface area, functional group, optical band gap, and thermal property were investigated by XRD, SEM, BET, FTIR, UV–Vis, and TGA/DTA techniques. The XRD results showed the formation of single-cubic Co3O4 nanostructured materials with an average crystal size of 19.37 nm and 12.98 nm for pristine Co3O4 and 0.25 M Ag-doped Co3O4 NPs. Morphological studies showed that pristine Co3O4 and 0.25 M Ag-doped Co3O4 NPs having a porous structure with small spherical grains, porous structures with sponge-like structures, and loosely packed porous structures, respectively. The pristine and 0.25 M Ag-doped Co3O4 NPs showed BET surface areas of 53.06 m2/g, and 407.33 m2/g, respectively. The band gap energy of Co3O4 NPs were 2.96 eV, with additional sub-bandgap energy of 1.95 eV. Additionally, it was discovered that the band gap energies of 0.25 M Ag-doped Co3O4 NPs ranged from 2.2 to 2.75 eV, with an extra sub-band with energies ranging from 1.43 to 1.94 eV for all as-prepared samples. The Ag-doped Co3O4 as prepared samples show improved thermal properties due to the doping effect of silver. The CV test confirmed that the 0.25 M Ag-doped Co3O4 NPs exhibited the highest specific capacitance value of 992.7 F/g at 5 mV/s in a 0.1 M KOH electrolyte solution. The energy density and power density of 0.25 M Ag-doped Co3O4 NPs were 27.9 W h/kg and 3816.1 W/kg, respectively.

Keywords

• Doping
• Cobalt oxide
• Nanoparticles
• Co-precipitation method
• Supercapacitor