Ag doped Co3O4 nanoparticles for high-performance supercapacitor application

Ag doped Co 3 O 4 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 Co 3 O 4 nanostructured materials with an average crystal size of 19.37 nm and 12.98 nm for pristine Co 3 O 4 and 0.25 M Ag-doped Co 3 O 4 NPs. Morphological studies showed that pristine Co 3 O 4 and 0.25 M Ag-doped Co 3 O 4 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 Co 3 O 4 NPs showed BET surface areas of 53.06 m 2 /g, and 407.33 m 2 /g, respectively. The band gap energy of Co 3 O 4 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 Co 3 O 4 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 Co 3 O 4 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 Co 3 O 4 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 Co 3 O 4 NPs were 27.9 W h/kg and 3816.1 W/kg, respectively.