Effect of Dissolved Sulfide on Photoelectrochemical Characteristics of CdS Electrode

Abstract

The polarization characteristics of a sintered CdS electrode in aqueous Na2SO4 solution (basic solution) under illumination were studied. The anodic photocurrent began to flow at ca. -1.45 V vs. SCE in a solution containing S^2- ion, but it began to flow at ca. -0.7 V in a solution without S^2- ion. The oxidation of S^2- ion in a solution by a hole to change it into an elemental sulfur at the anode occurred in preference to the photodecomposition of a CdS electrode itself. In a solution containing sufficiently concentrated S^2- ion, the deposited sulfur at the anode by the photoelectrochemical reaction dissolved in S^2- ion to form polysulfide ion (Sx2-). Due to the above reaction, the photocurrent during the photoelectrolysis of the cell showed a steady value. On the basis of these results, an electrochemical photocell using undissolved CdS anode could be realized.