Synergistic Photocatalytic Degradation of Phenol Using Precious Metal Supported Titanium Dioxide with Hydrogen Peroxide

A series of precious metal catalysts (M/titanium dioxide [TiO 2 ], M = Ru, Rh, Pd, Ag, Ir, Pt, or Au) were prepared by a light deposition method, and for the first time, synergistic effects of photocatalytic degradation of phenol (20 mg/L) under UV irradiation (365 nm) by M/TiO 2 with electron capture agent hydrogen peroxide (H 2 O 2) have been investigated. Results showed that H 2 O 2 plays a great synergistic role on M/TiO 2, and the photocatalytic activity of M/TiO 2 is closely related to its work function. Ag loading greatly enhanced activity of TiO 2 due to the normal reduction mechanism and the " activated" mechanism between H 2 O 2 and Ag nanoparticles. Under the optimum conditions of Ag loading at 0.5 wt.%, Ag/TiO 2 concentration at 0.1 g/L, H 2 O 2 concentration at 50 mmol/L, and pH value of the reaction solution at 5, the phenol can be degraded by 65% within 3 h, which is 45% more than that in the TiO 2 photocatalytic system. Kinetics of the degradation of phenol can be characterized as pseudo-first order. Such synergistic photocatalytic degradation by precious metal supported TiO 2 with H 2 O 2 provides a new approach for the degradation of refractory pollutants in waste water.