Most of the work has been done on the optical properties of the rare earth doped CePO4, so there are few studies on the effect of metal ion doping on CePO4. The doping improves the properties of the compounds and can lead to new properties. It is the first time, that multi- ionic doping process is used in the CePO4matrix, in order to improve the ionic conductivity and the electrochemical stability. The low percentage of (Cd2+, Li+), Cr3+, Bi3+ dopant affect the structure showing a weak decrease in the lattice parameters compared to the CePO4. Impedance spectroscopy analysis was used to analyze the electrical behavior of samples as a function of frequency at different temperatures. The total electrical conductivity plots obtained from impedance spectra shows an increase of the total conductivity as Li, Cr-content increases. The determined energy gap values decrease with increasingly Li+, Cr3+ and Bi3+ doping content. Electrochemical tests showed an improved capacity when increasing the Li+, Cr3+ and Bi3+ content and a stable cycling performance.
Part of the book: Electrochemical Impedance Spectroscopy
The Fe2O3/TiO2 nanocomposite was synthesized on FTO subtract via hydrothermal method. The crystal structure, morphology, band structure of the heterojunction, behaviors of charge carriers and the redox ability were characterized by XRD, HR-TEM, absorption spectra, PL, cyclic voltammetry and transient photocurrent spectra. The as-prepared Fe2O3/TiO2 photocatalysts with distinctive structure and great stability was characterized and investigated for the degradation of methylene blue (MB) dye in aqueous solution. The ability of the photocatalyst for generating reactive oxygen species, including O2− and.OH was investigated. It was revealed that the combination of the two oxides (Fe2O3 and TiO2) nano-heterojunction could enhance the visible response and separate photogenerated charge carriers effectively. Therefore, the remarkable photocatalytic activity of Fe2O3/TiO2 nanostructures for MB degradation was ascribed to the enhanced visible light absorption and efficient interfacial transfer of photogenerated electrons from to Fe2O3 to TiO2 due to the lower energy gap level of Fe2O3/TiO2 hybrid heterojunctions as evidenced by the UV–Vis and photoluminescence studies. The decrease of the energy gap level of Fe2O3/TiO2 resulted in the inhibition of electron–hole pair recombination for effective spatial charge separation, thus enhancing the photocatalytic reactions. Based on the obtained results, a possible mechanism for the improved photocatalytic performance associated with Fe2O3/TiO2 was proposed. The Fe2O3/TiO2 nanocomposite has a specific capacity of 82 F.g−1 and shows a higher capacitance than Fe2O3.
Part of the book: Electrocatalysis and Electrocatalysts for a Cleaner Environment