Enhanced photocatalytic degradation rates at rutile TiO₂ photocatalysts modified with redox co-catalysts

Nanocrystalline rutile TiO₂ powders were modified with small amounts of CuO_x and FeO_x clusters by impregnation and drying. The modified rutile samples exhibited drastically enhanced photocatalytic degradation of 4-chlorophenol under UV + vis (λ > 320 nm) irradiation. The reaction rates were increased by the factor of 7 and 4 for the optimized TiO₂(R)-CuO_x and TiO₂(R)-FeO _x samples containing 0.12 wt.% Cu and 0.13 wt.% Fe, respectively. The visible light (λ > 455 nm) activity in 4-CP degradation was negligible. Photopotential transient measurements have confirmed that amorphous CuO_x and FeO_x clusters deposited at the surface of rutile TiO₂ act as efficient co-catalysts for oxygen reduction by photogenerated electrons, which leads to improved charge separation and diminished recombination. This study shows that simple modification of TiO ₂ photocatalysts with redox co-catalysts based on metal oxides is a promising strategy for enhancing the photocatalytic activity in degradation of aqueous pollutants.