Enhanced electrochemical properties for better stability of supercapacitance and electronic structure characteristics of Ag-doped CeO2 nanoparticles

Abstract

The structure and functional properties of materials can be significantly influenced by the synthesis of nanoparticles. This manuscript presents undoped CeO₂ and Ag doped CeO₂ nanoparticles (NPs) with different concentration of Ag (x = 0.03, 0.05 and 0.07), prepared using a simple coprecipitation route of synthesis. The prepared NPs have been characterized via X-ray diffraction (XRD), UV-Vis NIR spectroscopy, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS) and electrochemical analysis. The XRD measurement infers the improvement in the crystalline nature with Ag-doping and crystallite size between 13 and 9 nm. The absorption spectra reflect the red shifting of the absorption peaks along with the narrowing of band gap with rise in the Ag concentration. To ascertain the defects and excitation wavelength, PL measurement has been performed. High color rendering index (CRI) of the prepared samples showed good luminescence with white light emission. The development of oxygen vacancies (V_o) upon Ag doping is further confirmed by XPS measurement. In addition, the XPS measurements revealed the charged oxygen vacancies as well as the valence states of Ce with 3+ and 4+ , Ag with 1+ , and O with 2–. The CV test verified that in 2 M KOH electrolyte solution, the 5 % Ag-doped CeO₂ NPs had the maximum specific capacitance (C_SP) value of 363.44 F/g at scan rate of 10 mV/s the best cycle stability (retaining 93.90 % after 2100 cycles). It was discovered that the 5 % Ag-doped CeO₂ NPs had an energy density of 125.08 Wh/kg and a power density of 652.48 W/kg. An excellent super capacitive performance of Ag doping in CeO₂ could be used as a unique electrode material to develop high-efficiency and durable energy storage devices and resulted in the enrichment of electrochemical properties of these nanomaterials. Cyclic voltammetry (CV) results are consistent with electrochemical impedance spectroscopy, indicating good voltammetry and impedance spectroscopy performance of Ag-doped CeO₂ NPs. These nano-materials are also better alternatives for solid state electrolyte for fuel cells, UV blockers, photo-catalyst and many other applications.