Lead oxide cyclic voltammogram

If the voltammetric scan is not reversed after the first oxidation, a second oxidation (Epa = 0.2-0.3 V) is observed (Figure 6c). This oxidation renders the lower potential oxidation irreversible (Epa = 0-0.1 V) and also leads to the observation of an irreversible reduction at negative potentials (Epc = —0.8 to —0.9 V). It has not been possible to measure accurately the number of electrons involved in either the second oxidation or in the coupled reduction process by coulometry due to the formation of films on the electrode surfaces. However, in comparison with that observed for the first oxidation, the peak currents are consistent with one- and two-electron processes, respectively. In spite of the irreversible nature of the cyclic voltammogram, continuous cycling be-... 

Half-sandwich complexes [Rh (Cp)(CO)(L)] with L = CO, PPha, PMes, and P(OPh>3 all reveal irreversible oxidation waves in cyclic voltammograms. In all cases, the intermediate 17 VE electron monocationic species couple to give dinuclear species. For L = CO and PPh3, the oxidation leads to formation of fulvalene complexes (87-89). This reaction could proceed via C—C coupling of two Cp ligands with a net loss of H2, followed by Rlu Rh bond formation [path (a) in Fig. 24]. 

Electrochemical studies have revealed that indeed 6-hydroxydopamine is very easily oxidized. A cyclic voltammogram of 6-hydroxydopamine at a carbon paste electrode at pH 7 is shown in Figure 4. The evidence leads to the conclusion that peak la is a 2e-2H electrooxidation of 6-hydroxydopamine... 

Figure 1. A continuous scan cyclic voltammogram of nickel(II) tetrakis(3-methoxy-4-hydroxyphenyl)porphyrin [(TMHPP)Ni] indicating film formation (a), reaction pathway for the electrochemical oxidation of MHPP)Ni in basic aqueous media (l-ll) and the reaction leading to polymerization of fully oxidized (TMHPP)Ni (lll-V)...

Fig. II.1.25 (a) Schematic representation of the transfer of anion from the aqueous into the organic phase upon oxidation of Mn(II)TPP to Mn(III)TPP . (b) In the presence of the boronic acid B as a facilitator the tiansfer of the anion A leads to the formation of the complex AB in the oiganic phase, (c) Cyclic voltammograms [120] (scan rate 10 mVs ) for the oxidation and le-ieduction of 75 mM Mn(II)TPP dissolved in PPP (4-(3-phenylpropyl)-pyridine, 75 nL) and immobilised in the form of microdroplets onto a 4.9-mm diameter graphite electrode immersed in aqueous 0.1 M sodium lactate pH = 7.34. The presence of (i) 0 and (ii) 973 mM naphthyl-2-borDnic add is shown to cause a negative shift in the voltammetric response, (d) Plot of the midpoint potential versus the natural logarithm of the naphthyl-2-boronic add concentration in the microdroplets. Lines indicate calculated data [120] for reversible lactate-4)oronic add complex formation for three equilibrium constants...

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