Electronic structure of TiO2:Ru

Selectivity between Oxygen and Chlorine Evolution in the Chlor-Alkali and Chlorate Processes

Chlorine gas and sodium chlorate are two base chemicals produced through electrolysis of sodium chloride brine which find uses in many areas of industrial chemistry. Although the industrial production of these chemicals started over 100 years ago, there are still factors that limit the energy efficiencies of the processes. This review focuses on the unwanted production of oxygen gas, which decreases the charge yield by up to 5%. Understanding the factors that control the rate of oxygen production requires understanding of both chemical reactions occurring in the electrolyte, as well as surface reactions occurring on the anodes. The dominant anode material used in chlorate and chlor-alkali production is the dimensionally stable anode (DSA), Ti coated by a mixed oxide of RuO2 and TiO2. Although the selectivity for chlorine evolution on DSA is high, the fundamental reasons for this high selectivity are just now becoming elucidated. This review summarizes the research, since the early 1900s until today, concerning the selectivity between chlorine and oxygen evolution in chlorate and chlor-alkali production. It covers experimental as well as theoretical studies and highlights the relationships between process conditions, electrolyte composition, the material properties of the anode, and the selectivity for oxygen formation.

Unprecedented coloration of rutile titanium dioxide nanocrystalline thin films

In this communication, TiO2 nanocrystalline thin films synthesized by a room temperature (27 degrees C) chemical dip process. To our knowledge, this is first report of the preparation of nanoscale rutile TiO2 particles from common inorganic salt at such low temperature. Interestingly, unprecedented dynamic color change accompanies with titanium dioxide grain size, which can be seen with the naked eye that generated curiosity in our mind to check UV-vis absorption, where significant changes were observed. The room temperature synthesized thin films of rutile titanium dioxide make it a potential candidate for high-compatibility material, which can be used in artificial heart valves.

Oxidation behavior of Ru/TiO2 and metallic Ru fine particles on heating in air

Thermogravimetry (TG) and differential thermal analysis (DTA) were used to investigate the oxidation behavior of Ru/TiO2 and metallic Ru fine particles during heating in air in the range 20-1000 degrees C. Temperature ranges of the oxidation for two samples of Ru/TiO2 with the compositions (92 wt% Ru, 8 wt% TiO2) and (75 wt% Ru, 25 wt% TiO2) and for pure metallic Ru fine particle agglomerates were determined. It was assumed that after the partial oxidation of Ru in the sample containing 75 wt% Ru and 25 wt% TiO2 and in the pure metallic Ru a diffusion barrier was formed, preventing further oxidation of Ru in Ru/RuO2 and Ru/RuO2/TiO2 matrices. XRD and TEM were used for the sample characterization.