Cyclic voltammetry passivation

Cyclic voltammetry (adsorption, monolayers) Potentiodynamic polarisation (passivation, activation) Cathodic reduction (thickness) Frequency response analysis (electrical properties, heterogeneity) Chronopotentiometry (kinetics)... 

A comparison of the products of AP hydrolysis of HQDP (HQ), PP, and 1-NP using cyclic voltammetry revealed that HQ produced well-defined peaks, and that the oxidation of HQ is reversible. More importantly, no apparent passivation of the electrode surface was observed even at high millimolar concentrations after 50 scans. Following a series of investigations, this non-fouling nature of HQ was attributed to the non-accumulation of its oxidation products on the electrode surface and the good diffusional properties of HQ at the electrode-solution interface. Another positive feature of HQDP as a substrate for AP is a tenfold greater oxidation current response of HQ compared to those obtained in the presence of PP or 1-NP. Overall, HQDP provides a suitable and attractive alternative substrate system for AP in the development of amperometric immunosensors. 

The electrochemical reduction of 02 in aptotic media is dramatically changed by the presence of electroinactive metal cations.2 Figure 9.5 illustrates the effect of a fivefold excess of [Znu(0H2)6](C104)2, [Znn(dimethylurea)6] (C104)2, and [Znu(bpy)3](C104)2 on the cyclic voltammetry of 02 in DMF at a platinum electrode. Prior to each reductive scan the electrode has been repolished a second scan yields a much reduced peak current. In the presence of an excess concentration of Zn(II) cations the reduction of 02 is a totally irreversible process, and the electrodes (Pt, Au, and C) are passivated after the initial negative scan. 

In general the electrochemical stability of an electrolyte is experimentally evaluated by means of cyclic voltammetry. However, the determination of the electrochemical windows exhibits several problems. First, the electrochemical degradation or breakdown of an electrolyte is an irreversible reaction, thus there is no theoretical redox potential [40, 41], Passivation of the electrodes often makes it difficult to identify the onset of the reaction due to inhibition of further reactions [40, 42],... 

Oxidizing Virus Electrode with Cyclic Voltammetry to Test Surface Passivation... 

PPy has also been used in combination with CNTs to obtain an anticorrosion coating. Hermas [69] studied PPy-CNTs coating applied on stainless steel by in situ EP of PPy-oxidised multi-walled carbon nanotubes (MWCNTs) and PPy-oxidised SWCNTs composites from 0.1 M oxalic acid by using cyclic voltammetry. The results show that the addition of the oxidised carbon nanotubes greatly enhances the EP process, especially in the case of oxidised SWCNTs. Similar results are reported in Ref. [70], referring to electrodeposition of a nanocomposite coating made of oxidised CNTs and poly(o-phenylenediamine) (PoPD) on a stainless steel. Also in this case the presence of the CNTs enhances the deposition of the PoPD and this enhancement is more evident with SWCNT than with MWCNTs. The nanocomposite coating keeps the stainless steel in a passive state in an acidic solution. 

Many useful synthetic reactions cannot be carried out electrochemically because of the passivation of the electrode by the starting materials, reaction intermediates, or products [8, 11]. One possible solution is the ultrasound-induced formation of emulsions from biphasic systems so that the electrode process of interest occurs in the aqueous phase but the organic component constantly dissolves and removes the electrode passivating species. An example is the electroreduction of MG (see Fig. 8). MG is soluble in water, but the product of its two-electron reduction, 1-MG, is not (19, 35]. Silent cyclic voltammetry of a 0.2 mM solution of MG in... 

Several ring-substituted anilines (o-toluidine, m-toluidine, o-anisidine, and o-chloroaniline) were electrodeposited on passivated Fe surfaces by cyclic voltammetry, potentiostatic, or galvanostatic techniques from aqueous oxalic acid solutions [180]. With the exception of o-chloroaniline, the films exhibited protective properties against corrosion of Fe in sulfuric acid solution by stabilizing the Fe passive state, though performance was slightly poorer than that of polyaniline. 

---