Photodissolution of iron oxides II: The lack of efficiency of thiocyanate

Abstract

Thiocyanate does not enhance, and even inhibits, the photochemical dissolution of iron oxides at 254 nm. At low SCN− concentrations, surface complexes [Formula: see text] are formed only to a small extent due to the low affinity for the surface by the monovalent anion, and electron-hole pairs essentially recombine. At higher ligand concentrations, only the homogeneous photolysis of SCN− is observed. At 450 nm, there is no appreciable light absorption by the oxide but homogeneous photolysis of FeIII—SCN− complexes produces FeII, which dissolves the oxide by a reductive mechanism. Keywords: iron oxides photodissolution, thiocyanate heterogeneous photochemistry, metal oxides surface complexation.