Rotating disk electrode modified electrodes

Figure 3 Plots of the total number of electrons Ut (a), of the Tafel slope b (b), of the limiting current density IjA,-, (c) and of the exchange current density I/A (d), versus the platinum loading for the reduction of oxygen on a platinum-modified polyaniline-glassy carbon rotating disk electrode (O2 saturated 0.5 M H2SO4 2mVs 25 °C A, is the true surface...

UTCFC has modified the carbothermal synthesis process (U.S. Patent 4,677,092, US 4,806,515, US 5,013,618, US 4,880,711, US 4,373,014, etc.) to prepare 40 wt% ternary Pt alloy catalysts. Various high-concentration Pt catalyst systems were synthesized and the electrochemical surface area (EGA) and electrochemical activity values compared to commercially available catalysts (see Table 3). The UTCFC catalysts showed EGA and activity values comparable to the commercial catalysts. A rotating disk electrode technique for catalyst activity measurements has been developed and is currently being debugged at UTCFC. 

Figure 8.4 shows the importance of the coordination mode around the metal ion for the electrochemical properties of the layer. In Fig. 8.4 the mediation of the Fe(II)/(III) oxidation is studied by using a rotating disk electrode. Initially a thin film of [Ru(bipy)2(PVP)5Cl] is used and with this coating the current potential curve I is obtained (see Fig. 8.4b). On photolysis of the coating and formation of the aquocomplex (according to Reaction 5) curve II is obtained. Rotating disk behavior very clearly shows that the redox potential of the modifying layer is of prime importance to the electrochemical properties of the modified electrode.

Figure 8.28. (a) Cyclic voltammograms (scan rate = 100 mV s ) and (b) hydrodynamic voltammograms (scan rate = 10 mV s electrode rotation rate = 400 rpm) of a vitreous carbon disk electrode modified with a film of poly[Mn(III)-32] in DCM + 0.1 mol BU4NBF4 under argon (curve 1), in the presence of dissolved oxygen (curve 2) and in the presence of dissolved oxygen and 0.1 M benzoic anhydride (curve 3). Adapted from ref. [241]... 

Chronoamperometry (55) and rotating disk electrode (56) studies are primarily used to obtain information on the electrode process of interest, in particular the effective diffusion coefficient which is important in optimizing sensor performance. The effective diffusion coefficient accounts for the diffusion of charge which may occui in the modifier. This information is... 

Masa J, Batchelor-McAuley C, Schuhmann W, Compton RG (2014) Koutecky-Levich analysis applied to nanoparticle modified rotating disk electrodes electrocatalysis or misinterpretation. Nano Res 7(l) 71-78... 

For the in situ characterization of modified electrodes, the method of choice is electrochemical analysis by cyclic voltammetry, ac voltammetry, chronoamperometry or chronocoulometry, or rotating disk voltametry. Cyclic voltammograms are easy to interpret from a qualitative point of view (Fig, 1). The other methods are less direct but they can yield quantitative data more readily. 

Fig. 3. Steady state concentration profiles of catalyst and substrate species in the film and diffusion layer for for various cases of redox catalysis at polymer-modified electrodes. Explanation of layers see bottom case (S + E) f film d diffusion layer b bulk solution i, limiting current at the rotating disk electrode other symbols have the same meaning as in Fig. 2 (from ref.

Fig. 8 Catalysis of O2 reduction at a ring-disk electrode in contact with an aqueous 0.5 M H2SO4 solution, the graphite disk (EPGE) being modified by adsorption of a biscobalt diporphyrin, C02ETE4. (a) Disk current, solution saturated with oxygen, p02 = 1 atm rotation rate 100 r min scan rate ...

Figure 5.71 Rotating-disk voltammograms showing the reduction of a 0.2 m/mM [Fe(H20)6]3+ solution in 0.1 M H2SO4 at an electrode modified with [Os(bpy)2(PVP)ioCl]+. The rotation rates, from top to bottom, are 500,1000,1500,2000,2500 and 3000 rpm, respectively the surface coverage is 5 x 10-9 mol cm 2. From R. J. Forster and J. G. Vos,. Chem. Soc., Faraday Trans., 87,1863-1867 (1991). Reproduced by permission of The Royal Society of Chemistry...

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