Plasma Electrolytic Formation and Photoelectrochemical Properties of Zr- and/or Ce-Containing Oxide Layers on Titanium

Ti/TiO2-ZrTiO4-ZrO2, Ti/TiO2-CeO2, and Ti/TiO2-ZrTiO4 composites have been fabricated by the one-stage plasma electrolytic oxidation (PEO) in aqueous electrolytes containing 0.05 mol/L Zr(SO4)(2), 0.05 mol/L Ce(SO4)(2), or their mixtures, respectively. The surface morphology and composite composition have been studied by scanning electron microscopy, X-ray powder diffraction, and energy dispersive analysis. The photoelectrochemical properties of the composites have been studied under UV light in the potential range of 0.0-1.2 V. The Ti/TiO2-ZrTiO4-ZrO2 composites exhibit high photoelectrochemical activity: they generate photocurrents of 73 mu A without potential and 230 mu A in the potential range from 0.2 to 1.2 V. Such composites are promising as active photoanodes for water splitting. The introduction of cerium into the PEO coatings leads to a sharp decrease in photocurrents (0.1-10 mu A).