Electrodes catalyst-derivatized

Figure 27.18 Common configuration for postcolumn reactors with electrochemical analysis. (A) LC-chemical reaction-EC. Postcolumn addition of a chemical reagent (for example, Cu2+ or an enzyme). (B) LC-enzyme-LC. Electrochemical detection following postcolumn reaction with an immobilized enzyme or other catalyst (for example, dehydrogenase or choline esterase). (C) LC-EC-EC. Electrochemical generation of a derivatizing reagent. The response at the second electrode is proportional to analyte concentration (for example, production of Br2 for detection of thioethers). (D) LC-EC-EC. Electrochemical derivatization of an analyte. In this case a compound of a more favorable redox potential is produced and detected at the second electrode (for example, detection of reduced disulfides by the catalytic oxidation of Hg). (E) LC-hv-EC. Photochemical reaction of an analyte to produce a species that is electrochemically active (for example, detection of nitro compounds and phenylalanine). Various combinations of these five arrangements have also been used. [Reprinted with permission from Bioanalytical Systems, Inc.]...

The catalytic activity of these oxometalates is well documented [360, 361]. An inactive surface of Ti02 becomes an efficient catalyst for H2 evolution as it is derivatized with silicotungstic acid [362, 363]. However, while real electrocatalytic effects seem likely for a pigmented Ni surface in view of the lower Tafel slope observed (which can also be due to some activation of the Ni itself), these are not completely established for the surface of pure oxometalates surface area effects could be entirely responsible for the apparent activation. The real surface state of these electrodes deserves to be further investigated since these materials might fall into the category of amorphous phases. 

Figure 2.21 Chronoamperometry reveals the potential and time dependence of the catalytic effect of SPS derivatization. (a) At smaller overpotentials, pre-adsorbed catalyst on the electrode is rapidly deactivated, (b) In contrast, the catalytic effect is sustained for thousands of seconds at higher overpotentials. Practical plating is performed under the latter conditions [136].

Figure 2.35 Sequential feature filling images for trenches that were pre-treated with SPS/M PS catalyst prior to copper plating for indicated times in a PEG-CI electrolyte at — 0.25 V. The conditions used for electrode derivatization are indicated (source Ref. [343]).

Figure 2.36 Simulations of feature filling of correspond to those anticipated for the catalyst pre-treated electrodes. Interface motion derivatization treatments specified in is displayed using colorized contour lines to Figure 2.35. The feature filling times reflect the local catalyst coverage. Each corresponding to the last growth contour are ...

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