Ruthenium oxide electrode modification

The use of iodate and periodic acid as oxidizers for noble metal CMP has also been attempted. Similar to W CMP, a surface oxidation or modification is required for the subsequent removal by mechanical force. For example, the potential use of ruthenium as bottom electrode capacitor for next-generation DRAM devices [40] has been explored. Owing to the fact that a dry-etch process can lead to the formation of toxic RUO4 [41], the possibility of using CMP to implement Ru has gained interest recently. The studies in this area have indicated that the formation of stable passive layers such as RUO2 [41,42] and RU2O5 [42] are important steps in the Ru CMP. 

Metal oxide electrodes have been used with or without modification [9, 15-18]. Tin oxide and indium oxide are semiconductors, while ruthenium dioxide is a metallic conductor. All of these yield direct electrochemistry of cytochrome c, while modification with amine groups produces a positively charged surface that can be used for negatively charged proteins, such as the small Fe-S proteins known as ferredoxins [18]. 

Lamy et al. [37] have done extensive research on methanol adsorption and oxidation on fuel cell through radioactive labeling study and FTIR measurements. Kinetics of formation of surface and bulk products coming from methanol and surface/bulk exchange processes were found to be significantly different on Pt compared to Pt/Ru [38,39]. Modifications of the electronic surface of platinum atoms by ruthenium were clearly seen in the electrode structure. Adsorption of carbon monoxide from methanol... 

The controlled deposition of ruthenium on well-defined surfaces, such as Pt(hkl) [95-103] and Au hkl) [38-40], has been characterized by electrochemical measurements, Fourier transform infrared reflection-absorption spectroscopy (FT-IRRAS), XPS and STM measurements. The interest in these studies is mainly concentrated on the ruthenium modification of a platinum surface because of its extreme importance in electrocatalysis. It has been demonstrated that a ruthenium-deposited Pt( 111) substrate showed an extremely high activity in methanol oxidation compared to ruthenium-deposited Pt(hkl) electrodes with other crystallographic orientations [98, 99]. 

Electrochemical oxidation catalysts with ruthenium centers are the basis of several amperometric detectors that permit determination of a variety of biochemical compounds at the sub-micromolar level in flow systems. Modification of glassy carbon electrodes with films of mvRuOx is particularly useful for peptides that contain sulfur. Oxidation to polar products that are not adsorbed on the electrode occurs by concurrent oxygen and electron transfer. These electrodes have longterm stability as long as the analytes are at concentrations below about 10 pM. 

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