The Electrochemical Oxidation of Aqueous Sulfur Dioxide I. Experimental Parameter Influences on Electrode Behavior

作者：O'Brien J A^*; Hinkley J T; Donne S W

来源：Journal of the Electrochemical Society, 2010, 157(9): F111-F115.

DOI：10.1149/1.3458860

The oxidative behavior of aqueous sulfur dioxide has been assessed on a polycrystalline platinum electrode using cyclic voltammetry with variation in applied experimental parameters. Parameters varied include the acid concentration, reaction temperature, and lower potential limit (E(low)). Three distinctly different oxidation scenarios were identified. These are defined by E(low) and, at E(low) < 0.2 V, acid concentration as well. Observed oxidation scenarios include a limited response (scenario 1), catalytic oxidation (scenario 2), and reaction inhibition (scenario 3). Scenario 1 required an activation energy of E(A) = 83 kJ mol(-1) with a Tafel slope of b = 114 mV and transfer coefficient of alpha(A) = 0.49. Scenario 2 was found to have a different reaction mechanism to scenario 1 (alpha(A) = 0.21), displaying faster reaction kinetics (b = 74 mV) and catalytically improved oxidation onset (E(A) = 51 kJ mol(-1)). The onset of scenario 2 oxidation was dependent on oxidation kinetics, not thermodynamics, with dE(onset)/dT = -2.132 mV K(-1). The variable response of the electrode is discussed in terms of sulfur species adsorption, including the reductive formation of adsorbed sulfur at potentials less than 0.5 V, and the adsorption of sulfur dioxide with varying adsorption strength.

• 出版日期2010