Improved Visible Photocatalytic Activity on Titania Modified with −O–Pd–Cl Species Assisted by Oxidative Addition Reaction of Pd0

Abstract

We introduce the idea of Pd catalysis used in cross-coupling reactions into photocatalysis. The −O–Pd–Cl surface species modified on nanoscale TiO2 can remarkably enhance the photocatalytic activity under visible-light irradiation in the degradation of 4-bromophenol. It is revealed that the catalytically active Pd0 is in situ generated by the reduction of photogenerated electrons from TiO2. The −O–Pd0–Cl species can react with 4-bromophenol to form hydroxyphenyl radicals via an oxidative addition reaction. The photocatalytic mechanism assisted by the oxidative addition reaction on −O–Pd–Cl species is also demonstrated. We were hence able to rationally tailor the coordination environment of Pd on the TiO2 surface to obtain high photocatalytic activity and selectivity.