Comparison of photocatalytic activities of 3d transition metal ions for hydrogen peroxide photolysis and photoinitiated hydroxylation of 2-hydroxybenzoic acid

Abstract

Quantum yields of hydrogen peroxide photolysis and photoinitiated hydroxylation of 2-hydroxybenzoic acid in the presence of 3 d transition metal ions have been measured. Marked photocatalytic effects were only observed for Cu(II) in hydrogen peroxide photolysis, and for Fe(III) in photoinitiated hydroxylation of 2-hydroxybenzoic acid. No photocatalytic activity was detected for the other 3 d transition metal ions investigated. Fe(III) and Cu(II) differ in their photocatalytic activities, suggesting that the simple concept of free OH . radical formation cannot explain the mechanisms of their action.