Synthesis, processing and characterization of nanostructured metal oxides as electrode materials

The performance of electrodes is of major importance to battery and electrolysis systems. The main functions of electrodes are to provide reaction sites for the electrochemical reactions to take place and to supply pathways for electrical conduction and mass transportation. Therefore, electrode materials must be very stable and have sufficient electrical conductivity, electrocatalytic activity and surface area at operating conditions. In the oxidative anode (electrolysis) or cathode (fuel cells) environment, only certain metal oxides could meet these requirements.; Nanostructured materials, such as mesostructured and nanosized particles can provide very high surface area. Mesostructured nickel oxide was formed in NiSO₄ and cetyltrimethylammonium bromide (CTAB) aqueous solution. Addition of sodium silicate in the solution stabilized the mesostructure. Mesostructured nickel silicate with specific surface area as high as 530 m 2/g was achieved. For improving the conductivity of electrodes, nanosized powders of Electrically conductive perovskite-type oxides such as LaNiO ₃ and La_1-x Sr_xMnNi_yO₃ were synthesized by a sol-gel co-precipitation method. By changing the amount x of A-site strontium substitution and y of nickel nonstoichiometry addition in La_{1- x}Sr_xMnNi_yO₃, the electrical conductivity of La_1-xSr_xMnNi_yO₃ at elevated temperatures in air could be improved.; Electrochemical properties of mesostructured NiO and perovskite-type oxides were investigated by cyclic voltammetry, steady-state polarization and AC-impedance techniques in strong basic solution at room temperature or in air at 800°C. The hybrid electrode of a mixture of mesostructured nickel silicate with nanosized powders of LaNiO3 shows remarkable specific capacitance of ∼83 F/g. Cathode of solid oxide fuel cell (SOFC) made of La 1-xSrxMnNiyO3 has lower (∼ factor of 2) interfacial resistance and overpotential than that of the most popular cathode material La_1-xSr_xMnO ₃. It indicates that La_1-x Sr_xMnNi_yO ₃ is a promising cathode material for SOFC application.