Novel Composition Graded Ti/Ru-Sb-SnO2 Electrode Synthesized by Selective Electrodeposition and Its Application for Electrocatalytic Decolorization of Dyes

Compositionally continuous gradient electrode of Ru-Sb-SnO2 was fabricated successfully by the selective potential-pulse electrodeposition method in a single electrolytic solution. Cyclic voltametry was used to determine the deposition potentials, obtaining a three-step potential mode. Applying the selected three-step potential pulse, a uniform layer with controllable composition gradient was obtained and had morphology of vertically aligned sheets. The Ru content in the deposition layer displays a parabolic variation and has a maximum value of 2.4 at. % with 200 deposition cycles. Furthermore, the growth mechanism of perpendicular sheet morphology and composition gradient was investigated and is related to the diffusion layer and applied potentials. Finally, the electrocatalytic dye decolorization experiments show that first-order kinetics constants on Ti/Ru-Sb-SnO2 electrode reach 23.0 x 10(-3) min(-1) (for methylene blue), 25.1 x 10(-3) min(-1) (for orange II), and 25.2 x 10(-3) min(-1) (for methyl orange), respectively. These results demonstrate that the compositionally continuous gradient electrode possesses a good catalytic activity and wide use for dye decolorization.