Synthesis of hierarchical structured rare earth metal–doped Co3O4 by polymer combustion method for high performance electrochemical supercapacitor electrode materials

In this study, hierarchical-structured Co3O4 nanocapsules and various rare earth metal (La, Nd, Gd, Sm)–doped Co3O4 materials were synthesized by a polymer-assisted combustion route. These rare earth metal–doped Co3O4 materials were tested as active electrode materials for high performance electrochemical supercapacitors. The Sm-Co3O4 electrode has shown an extraordinary electrochemical supercapacitor performance with high specific capacitance and exhibited a good cycling stability with the capacitance retention of 93.18% after 5000 cycles. The doping of rare earth metals in Co3O4 can reduce the charge transfer resistance and crystalline nature which are expected to improve the transfer of ions and electrons. Also, the large number of structural defects can promote the diffusion of electrolyte ion and electrochemical supercapacitance behavior. Furthermore, the antistructural modeling has shown that isovalent cation substitution leads to the formation of cation vacancies and interstitial defects, which enhance the electrochemical properties of doped Co3O4 materials.