Electrochemical Cell, Instrumentation, and Pretreatment

The electrochemical setup should be a three-electrode cell consisting of a SERS-active working electrode, an inert counter electrode, and a reference electrode. In most cases for aqueous electrolyte solutions, the counter electrode is a platinum wire and the reference electrode is a saturated calomel reference (SCE). If a deleterious species is produced at the counter electrode, it could be separated from the working and reference electrodes by a separate compartment with a ground glass frit separator. In most of the commonly used electrochemical SERS cells, such a separation has not been found to be necessary however, if SERS is to be used for the study of electrode processes, the use of a two-compartment cell might be a good precaution. 

FIGURE 8. Electrochemical cell for SERS with 90° collection geometry. 

The electrochemical instrumentation necessary for a SERS setup includes a potentiostat and a waveform generator. The latter should be capable of generating a potential pulse and a triangular waveform on top of an initial potential. For an Ag SERS electrode, two types of oxidation-reduction cycle (ORC) pretreatment techniques have been used, i.e., either a double potential 

FIGURE 10. Voltammograms of Ag electrodes in different electrolytes (a) 1 M KCl, (b) 0.1 M KCl, (c) 1 M KBr, and (d) 1 M KI. The corresponding voltammograms in the various electrolytes in the presence of 0.05 M pyridine are identical. The dotted vertical line indicates the starting potential for SERS scans. Adapted from Ref. 8 with permission. 

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