Why mostly GC disc and Pt ring RRDE is preferred for the detection of peroxide during ORR reaction? What will be the effect if the other ring electrode is used instead of Pt.
please take a look at this attached figure.
(Taken from "Fundamental Electrochemistry" course by Prof. David Eisenberg, Technion) .
H2O2 generated as an intermediate in O2 reduction can only reliably be detected by oxidation, since H2O2 reduction typically overlaps O2 reduction on most materials. H2O2 oxidation is very sensitive to electrode material e.g. barely happens on gold. Even on Pt, the current can also depend strongly on electrode history. This has resulted in an overestimate of the putative four electron pathway, due to misinterpretation of the low ring electrode current. This whole business is addressed in an ancient paper by Vilambi and Taylor: J. Electroanal. Chem., 270 (1989) 61-77, where the ring potential is continuously cycled to maintain its electrocatalytic performance.
For GC (strongly dependent on pre-treatment), the O2 reduction reaction in most aqueous electrolytes and pH values is the 2e- reduction with little evidence of further reduction of H2O2 to water.
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