Steady state ring-disk polarization curve

Figure 3.70 Steady state ring-disk polarization in 0.1 M NaOH before (A) and after pyrolysis curves for O2 reduction on a thin porous coating 800 °C, 2 h in Ar (B). Electrode cross-sectional electrode containing 4.7% w/w CoTMPP XC-72 area, 0.196cm2, co = 2500rpm, room (solid triangles), 4.8% w/w (FeTMPP)20 XC-72 temperature, Au Ering = +0.1 V versus SCE, (solid circles), 4.4% w/w H2TMPP XC-72 (solid N = 0.38. squares) and Vulcan XC-72 carbon (open circles)...

Figure 3.47 Upper panels steady state polarization curves recorded with a Pt OPG RRDE (co=100rpm) for coatings (6 x 10-8 mol citT2) of FeTPP (A), FePPIX (B) and FeTPyP (C) (see solid circles) deposited on the OPG disk in aqueous 02-saturated 0.1 M HCIO4 + 0.1 M NaCI04, where each ofthe points was collected for a freshly prepared coating. The data in empty circles are ring currents recorded...

A regime of simultaneous dissolution has also been found for Cu—Ni alloys in acidic chloride solutions. Rotating ring-disk electrode studies revealed an apparent Tafel region of the alloy and component polarization curves with mixed mass transfer and kinetic rate control [44, 45]. For a CugoNiio alloy, the kinetic parameters again indicate a coupling of the copper and nickel partial currents under steady state conditions [44]. 

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