Acid-treated Fe-doped TiO2 as a high performance photocatalyst used for degradation of phenol under visible light irradiation.

The photocatalytic activity of Fe-doped TiO2 nanoparticles is significantly increased by an acid-treatment process. The photocatalyst nanoparticles were prepared using sol-gel method with 0.5 mol% ratio of Fe:Ti in acidic pH of 3. The nanoparticles were structurally characterized by means of X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). It was observed that the photocatalytic activity suffered from an iron oxide contaminating layer deposited on the surface of the nanoparticles. This contamination layer was removed using an HCl acid-treatment process. The photocatalytic activity using 500 mg/L of Fe0.5-TiO2 in a 10 mg/L of phenol solution increased significantly from 33% to 57% (about 73% increase in the performance), within 90 min of reaction time under visible light irradiation. This significant improvement was achieved by removing the iron oxide contamination layer from the surface of the nanoparticles and adjusting pH to mild acidic and basic pHs.