Effect of Microstructure on Electrochemical Activity of Ru-La Oxide Coatings on Ti Substrate

Abstract:

Ru-La oxide coatings were prepared by thermal decomposition of the metal chlorides in the precursor solution of RuCl3×3H2O and LaCl3×7H2O. The electrochemical activity, structure and morphology of the coatings were characterized by cyclic voltammetry (CV), DSC-TG, XRD and atomic force microscope (AFM). The results show that the Ru-La oxide coatings exhibit a large electrochemical activity because of the smaller crystallite size and the larger surface active areas caused by the addition of La. The La addition increases the heat decomposing temperature of RuCl3 and restrains the crystallization and growth of RuO2 and RuOx (x>2). The mixed oxides mainly exist in the form of amorphous phase. The average crystallite size reaches a minimum value at the nominal La content of 30 mol%, while the oxide coating shows the highest electrochemical activity.

Key words:amorphous phase; oxide coating; lanthanum; RuO2; electrochemical activity