Thermal and Photochemical Reactions of Sulfhydryl Radicals. Implications for Colloid Photocorrosion

Article abstract of DOI:10.1021/j100290a060

Several thermal and photochemical reactions of sulfhydryl raducals, either in their monomeric (S radical/HS radical) or dimeric (H2S2(1-) radical) form, have been studied by using the pulse radiolysis technique.The dimer form is shown to react with O2 and methylviologen (MV(2+)).The tautomer reacts with O2 to produce a transient addition product, SO2(1-) radical, which further proceeds to give superoxide radicals.The dimer reacts slower with O2 by elecron transfer.The reaction of S(1-) radical/SH radical with MV(2+) yields several addition products which strongly absorb at λ_max = 485 nm.These are partially converted to MV(1+) radical, either through a unimolecular process or by reaction with another MV(2+) molecule.Implications of these observation for the photocorrosion of semiconductor colloidal sulfides are discussed.In particular, the possibility of reduction processes by surface-adsorbed sulfydryl radicals, produced by hole trapping at the colloid surface, is considered.