The Electrochemical Properties Of Pd/LaNiO₃Oxide Composite Thin Films In Alkaline Solution

ABO3perovskite-type oxide has great potential applications value due to the presence of low cost and high capacity. However, the current research about ABO3oxides as hydrogen storage materials is still in its infancy because of this type of oxide electrochemical kinetics of poor performance. There are still many critical and unresolved problems about perovskite-type oxide electrochemical reaction of hydrogen:the hydrogen storage and electrochemical reaction mechanism is still not clear in an alkaline aqueous solution, the electrochemical catalytic activity is poor, the electrochemical capacity contribution is unknown. Metal Pd not only has excellent electro-catalytic for activity hydrogen in the electrochemical deposition but also has a good hydrogen absorption properties in aqueous. Thin-film electrode has many characteristics. Studying ABO3oxide thin-film electrode in an alkaline aqueous solution has an electrode electrochemical behavior of large surface area, the electrode geometry and electrode structure controlled and thin film surface modification much easy.Therefore, this paper proposes using RF magnetron sputtering apparatus respectively Si(111) and Ni substrate preparation Pd film,LaNiO3film and Pd/LaNiO3composite films to improve LaNiO3film electrode in the electrochemical activity of alkaline aqueous solution. The influences of annealing and surface coating Pd on the phase structure, morphology, resistivity and electrochemical properties were investigated by XRD, SEM, EDS, four probe and electrochemical method. The results showed that after annealed at700＞for1h, LaNiO3films had better crystallinity with rhombohedral perovskite structure and the minimum resistivity of0.79m Ω·cm. LaNiO3perovskite structure was changed and the resistivity increased when the annealing temperature was higher than800℃. Pd film, LaNiO3film and Pd/LaNiO3composite film electrodes by testing electrode in an alkaline aqueous solution of the charge and discharge curve, circulation capacity curve and linear polarization curve, studied the annealing treatment and Pd capping on the electrochemical behavior of LaNiO3thin film electrode and the electrochemical properties of the single Pd film. The results of electrochemical measurement found that in alkaline metal Pd film had good electro-catalytic activity for hydrogen evolution and good electrochemical hydrogen storage properties, the maximum discharge capacity of130mAh/g. The discharge capacity of LaNiO3film was low, and the discharge capacity of Pd/LaNiO3composite film after annealing was200mAh/g. But by calculating the discharge capacity of Pd/LaNiO3film electrode after removing the capacity contribution of Pd was401.8mAh/g. Charge and discharge platform were-0.85V and-0.81V respectively. LaNiO3film electrodes and annealed Pd/LaNiO3composite film electrode exchange current densities were Io=3.17mA/g and I0=654.7mA/g.The electro-catalytic activity and electrochemical maximum capacity of Pd-capped LaNiO3composite film electrode were significantly improved.