Dimensionally Stable Anodes (DSA) were invented by Henri Beer in 1965 under the brand name DSA. These electrodes are characterized by their shape and structural integrity and included a catalytic coating with corrosion resistance properties [1-2]. These materials are very appealing for many applications because of their high chemical and electrochemical stability, low cost and exceptional ability to catalyze electrochemical reactions [3]. Also, DSA electrodes are able to produce hydroxyl radicals (^·OH) at the interface level, which may have a large number of applications [4-5]. DSA electrodes usually employ titanium as a support material and can be coated with oxides of transition metals. For this investigation, the electrodes were coated with IrO₂ and Ta₂O₅ due to their excellent performance.

There are many investigations focused on the applications of these types of electrodes, but it is necessary to increase the information related to titanium pretreatment and the mechanism of iridium and tantalum deposition in order to thoroughly understand the structure of such electrodes [6-9]. Studies focused on coating quality enhancement are important in order to increase their performance, catalytic properties and stability against corrosion.

A crucial factor for DSA synthesis is the titanium pretreatment, which aims to increase the electrode area and clean it in order to facilitate the deposition of transition metals. For this investigation, titanium electrodes were sandblasted and etched with oxalic acid [1-2]. Also, there are factors related to the deposition, such as the concentration of salts in the precursor solution and its subsequent thermal treatment.

The main goal of this research is to modify titanium electrodes with IrO₂ and Ta₂O₅ by electrochemical deposition and study the changes in the electrode surface during the different stages of pretreatment and modification, in order understand the deposition mechanism and to improve their catalytic activity in the generation of hydroxyl radicals at the interface level [3].

The modified surfaces were characterized by Cyclic Voltammetry (CV), Diffraction X-Ray (DRX), perfilometry, Scanning Emission Microscopy (SEM) and Energy Dispersive X-Ray spectroscopy (EDX). Additionally, the production of ^·OH was monitored by UV-Vis spectrophotometry.

References

1. P. Duby, The history of progress in dimensionally stable anodes, JOM 45 (1993) 41–43.

2. H.B. Beer, The invention and industrial development of metal anodes, J. Electrochem. Soc. 127 (1980) 303C-307C.

3. C. Comninellis, G.P. Vercesi, Characterization of DSA®-type oxygen evolving electrodes: Choice of a coating, J. Appl. Electrochem. 21 (1991) 335–345.

4. S. Fierro, A. Kapa³ka, C. Comninellis, Electrochemical comparison between IrO₂ prepared by thermal treatment of iridium metal and IrO₂ prepared by thermal decomposition of H₂IrCl₆ solution, Electrochem. Commun. 12 (2010) 172–174.

5. M.P. Groover, Fundamentos de manufactura moderna: materiales, procesos y sistemas. Prentice-Hall Hispanoamericana SA, Mexico, 1997.

6. M. Pérez-Corona, A. Corona, E.D. Beltrán, J. Cárdenas, E. Bustos, Evaluation of IrO₂-Ta₂O₅|Ti electrodes employed during the electroremediation of hydrocarbon-contaminated soil. Sustain. Environ. Res. 23 (2013) 279–284.

7. J.-Y. Lee, An investigation on the electrochemical characteristics of Ta₂O₅- IrO₂ anodes for the application of electrolysis process. Mater. Sci. Appl. 02 (2011) 237–243.

8. A.M.Z. Ramalho, C.A. Martínez-Huitle, D.R. da Silva, Application of electrochemical technology for removing petroleum hydrocarbons from produced water using a DSA type anode at different flow rates, Fuel 89 (2010) 531–534.

9. A. Yaqub, M.H. Isa, H. Ajab, Electrochemical degradation of polycyclic aromatic hydrocarbons in synthetic solution and produced water using a Ti/SnO₂-Sb₂O₅-RuO₂ anode. J. Environ. Eng. 141 (1) (2015) 1-8.