Working electrodes preparation

All SERS experiments were conducted with a polycrystalline silver working electrode prepared by press-fitting a 6 mm diameter cylinder of silver into one end of a 0.375 inch diameter Teflon rod through which a 6 nm diameter concentric hole had been drilled. Electrical contact was made via a copper wire soldered to the silver. The geometric area of the silver disk was 0.28 cm2. 

The Working Electrode Preparation and Thermal Diffusion Properties 148 Preparation of Self-Assembled Monolayers 150... 

Fig. 16. Small-scalo laboratory cell for preparative electrolysis. A, Pt gauze working electrode. B, Pt sheet secondary electrode. C, Reference electrode. D, Luggin capillary on a syringe barrel so that the position of the tip of the Luggin probe relative to the working electrode is readily adjustable. E, Glass sinter to separate anode and cathode compartments. F, Gas inlet to allow stirring with inert gas or the continuous introduction of reactant. G, Three-way tap where a boundary between the reference electrode and the working solutions may be formed.

After the electrolysis for 5 h at —0.15 V with the bubbling of O2 into W, the amount of CO2 produced was found to be 1.6 x 10 moles. A photoabsorption spectrum of the NB after electrolysis gave a peak at 780 nm. The peak was identical with that of the one electron oxidation product of DMFC, DMFC, which had been prepared coulometrically by using a column electrode with glassy carbon fiber working electrode [40]. This fact indicates that the electrolysis product was DMFC. The DMFC produced by the electrolysis was estimated to be 3.08 x 10 moles. 

The oxidation product in DCE, CQ, has a charge, and hence it may be liable to transfer to W. The transfer of CQ at the W/DCE interface was investigated by current-scan polarography. Here, CQ in DCE had been prepared by reducing CQ in DCE at a column electrode with carbon fiber working electrode [40]. The polarogram (curve 2 in Fig. 8) indicates that CQ transfers from DCE to W in the potential range more positive than -0.7 V. 

The interpretation of XPS data is not always straightforward as is exemplified by different conclusions drawn by different investigators for the same electrode reaction. These discrepancies can be overcome if certain standards for electrode preparation, emersion and transfer processes are developed. The effects of the relative complexity of the emersed electrochemical interface on XPS and UPS data analysis in terms of (electro)chemical shifts and work function changes have to be considered. 

Finally, we can also find in the literature arrangements where the working electrode is also the emitter part of the transducer, normally named as sonotrode [22] or sonoelectrode [41]. Some authors have used only the main emitter surface as electrode [42], see Fig. 4.2b, and other authors have used the fully surface tip as working electrode [43], see Fig. 4.2c. In theory, this arrangement assures that all the specific effects derived from the ultrasound field propagation are directly focused on the surface electrode. Not only the shorted-lived bubbles non-uniformly collapse on the electrode surface but also the electrode surface itself oscillates. This provides additional effects which have been specifically used in the nanoparticles preparation. 

Favaro and Fiorani [34] used an electrode, prepared by doping conductive C cement with 5% cobalt phthalocyanine, in LC systems to detect the pharmaceutical thiols, captopril, thiopronine, and penicillamine. FIA determinations were performed with pH 2 phosphate buffer as the carrier stream (1 mL/min), an injection volume of 20 pL, and an applied potential of 0.6 V versus Ag/AgCl (stainless steel counter electrode). Calibration curves were developed for 5-100 pM of each analyte, and the dynamic linear range was up to approximately 20 pM. The detection limits were 76, 73, and 88 nM for captopril, thiopronine, and penicillamine, respectively. LC determinations were performed using a 5-pm Bio-Sil C18 HL 90-5S column (15 cm x 4.6 mm i.d.) with 1 mM sodium 1-octanesulfonate in 0.01 M phosphate buffer/acetonitrile as the mobile phase (1 mL/min) and gradient elution from 9 1 (held for 5 min) to 7 3 (held for 10 min) in 5 min. The working electrode was maintained at 0.6 V versus Ag/AgCl, and the injection volume was 20 pL. For thiopronine, penicillamine, and captopril, the retention times were 3.1, 5.0, and 11.3 min, and the detection limits were 0.71, 1.0, and 2.5 pM, respectively. 

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