Electrochemistry for the Environment
Wastewater treatment technology is undergoing a profound transformation due to far-reaching changes in regulations governing the discharge and disposal of hazardous pollutants. Electrochemistry for the Environment first lays down the fundamentals of envir
- PDF / 1,452,611 Bytes
- 44 Pages / 439.37 x 666.142 pts Page_size
- 0 Downloads / 231 Views
Techniques of Electrode Fabrication Liang Guo, Xinyong Li, and Guohua Chen
3.1 Thermal Decomposition Method Metal oxides belong to a class of widely used catalysts. Application of the metal oxide electrodes expands into several areas, including environmental decontamination, analytical chemistry, fuel cells, materials science and catalysis, microelectronics, etc. (Fierro 2006). In this part, the fabrication of these electrodes applied in environmental decontamination field, mainly for pollutant mineralization and gas evolution, will be discussed. Dimensional stable anodes (DSAs) are such kind of catalytic electrodes, which consist of a mixture of metal oxides coated on metal, mainly titanium, substrate. Large-scale use of DSAs in chlor-alkali electrolysis industry came in the 1960s when Henri Beer invented this type of electrodes (Beer 1968, 1969, 1972, 1973). In the Journal of Electrochemical Society in 1980, Henri Beer reviewed his research and development on DSAs and the further industrial applications of the electrodes (Beer 1980). Due to the high stability under high current density loading and high electrical efficiency for chlorine gas production, mixed oxide of ruthenium and titanium on titanium substrate has become the most useful electrode in industrial application (Beer 1980). High stability means long working life time with stable working performance and little contamination to the environment from the dissolving of the metal oxides. High electrical efficiency is closely related with the electrocatalysis performance. Oxygen and chlorine gas evolution reactions are two competitive steps in chlor-alkali process. High-quality electrodes can improve the electrocatalytic activity of the desired reactions, such as chlorine gas evolution, but depress the electrocatalytic activity of the side reactions, such as oxygen gas evolution. Even for very low chloride concentrations, chlorine formation occurs on Ir–Ru oxide electrode and side reactions show significantly lower efficiency in this case (Bergmann and Koparal 2005). Bergmann and coworkers demonstrated that Ir–Ru
G. Chen () Chemical and Biomolecular Engineering Department, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong e-mail: [email protected] C. Comninellis and G. Chen (eds.), Electrochemistry for the Environment, c Springer Science+Business Media, LLC 2010 DOI 10.1007/978-0-387-68318-8 3,
55
56
L. Guo et al.
oxide have a higher chlorine production efficiency than IrO2 anodes (Bergmann et al. 2002). High stability and high electrocatalysis performance are the two most important research topics for studying or developing electrodes. Modified DSA-type electrodes have been developed recently. For example, iridium oxides have been investigated as electroactive component for the oxygen evolution reaction (Kotz and Stucki 1986; Rolewicz et al. 1988; Duby 1993; Ferrer and Victori 1994). Tantalum is the most suitable anode material owing to its high conductivity and excellent corrosion resistance in aggressive media
Data Loading...
