Orientation and Electrochemical Oxidation of Hydroquinone Chemisorbed on Platinum Electrodes in Various Weakly Surface-Active Supporting Electrolytes.

摘要

Studies on the adsorption, orientation and electrochemical oxidation of hydroquinone at smooth polycrystalline Pt electrodes in aqueous solutions of weakly surface-active electrolytes are reported. The electrolytes were compared with respect to how they influenced (i) the packing density vs. concentration curves, (ii) the oxidation n-values (n sub ox), and (iii) the packing density vs. electrode potential plots. Analytical measurements were based on thin-layer electrochemical methods. Six electrolytes were studied: HClO4(and NaClO4), H2SO4, H3PO4, NaF, NaPF6, and CsClO4. No significant electrolyte or pH-dependences were found for the T vs. c adsorption profiles. The n sub ox data for n superscript 6 and n superscript 2 orientations likewise were unaffected by changes in supporting electrolyte, although n sub ox was slightly lower at pH=7 than in 1 M H+. Changes in packing density with electrode potential correlate closely with adsorption of hydrogen (at E <0.00 V vs. AgCl reference) and oxygen (at E greater than 0.40 V); weak but noticeable features at E greater than 0.20 V are consistent wtih the expected variation in specific adsorption of anions of supporting electrolyte.