Loading...

Polysulfide poisoning of Ag electrocatalyst during L-ascorbate ion electro-oxidation in alkaline solution

Gobal, F ; Sharif University of Technology

939 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/S1872-2067(11)60331-8
  3. Abstract:
  4. L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10 -5 to 4.5 × 10 -4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy. Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation, with the poisoning effect of polysulfide ion being more pronounced in the potential range of -0.3 to -0.2 V/SCE. The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were, 10 -3 to 1 × 10 -2 s and 1 × 10 -4 to 1 × 10 -2 s, respectively depending on the potential used for the impedance analysis. Based on the cyclic voltammetry findings, a mechanism for L-ascorbate oxidation in the presence of polysulfide ions was proposed. Impedance calculations based on the kinetic analysis can account for the occurrence of a negative impedance in a potential region around -0.2 V/SCE in the Nyquist polts
  5. Keywords:
  6. Electro-oxidation ; Electrode poisoning ; L-ascorbic acid ; Polysulfide ; Silver ; Alkaline solutions ; Hydroxide solutions ; Impedance analysis ; Impedance calculations ; Ion oxidation ; Kinetic analysis ; L-Ascorbate ; Nyquist ; Poisoning effects ; Polysulfide ions ; Potential range ; Potential region ; Silver electrode ; Time constants ; Cyclic voltammetry ; Electrocatalysts ; Electrochemical impedance spectroscopy ; Ions ; Oxidation ; Polysulfides
  7. Source: Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 33, Issue 2 , 2012 , Pages 267-274 ; 02539837 (ISSN)
  8. URL: http://www.sciencedirect.com/science/article/pii/S1872206711603318