Visible-light detoxification and charge generation by transition metal chloride modified titania

Amorphous microporous metal oxides of titanium (AMM-Ti) modified with chlor ides of Pt-IV, Ir-IV, Rh-III, AU(III), Pd-II, Co-II, and Ni-II have been pr epared by the sol-gel method and characterized by various surface analytica l methods. These hybrid AMM-Ti powders are catalysts for the photodegradati on of 4-chlorophenol (4-CP) in aqueous solution when illuminated with visib le (lambda greater than or equal to 400 or 455 nm) or UV (lambda greater th an or equal to 335 nm) light. The initial rate depends on the dopant level and is highest at 3.0% Pt in the case of Pt-IV/AMM-Ti. When employed in a p hotoelectrochemical cell, the activity spectrum of the photocurrent extends downward to about 600 nm, as does the photodegradation of 4-CP. It is sugg ested that the metal salt acts as a redox-active chromophore, transmitting the photogenerated charges to the amorphous matrix.