Photocatalytic performance of nano-photocatalyst from TiO 2 and Fe 2O 3 by mechanochemical synthesis

Abstract

Nano-particles of homogeneous solid solution between TiO 2 and Fe 2O 3 (up to 10 mol%) have been prepared by mechanochemical milling of TiO 2 and yellow Fe 2O 3/red Fe 2O 3/precipitated Fe (OH) 3 using a planetary ball mill. Such novel solid solution cannot be prepared by conventional co-precipitation technique. A preliminary investigation of photocatalytic activity of mixed oxide (TiO 2/Fe 2O 3) on photo-oxidation of different organic dyes like Rhodamine B (RB), Methyl orange (MO), Thymol blue (TB) and Bromocresol green (BG) under visible light (300-W Xe lamp; λ > 420 nm) showed that TiO 2 having 5 mol% of Fe 2O 3 (YFT1) is 3–5 times higher photoactive than that of P25 TiO 2. The XRD result did not show the peaks assigned to the Fe components (for example Fe 2O 3, Fe 3O 4, FeO 3, and Fe metal) on the external surface of the anatase structure in the Fe 2O 3/TiO 2 attained through mechanochemical treatment. This meant that Fe components were well incorporated into the TiO 2 anatase structure. The average crystallite size and particle size of YFT1 were found to be 12 nm and 30 ± 5 nm respectively measured from XRD and TEM conforming to nanodimensions. Together with the Fe component, they absorbed wavelength of above 387 nm. The band slightly shifted to the right without tail broadness, which was the UV absorption of Fe oxide in the Fe 2O 3/TiO 2 particle attained through mechanochemical method. This meant that Fe components were well inserted into the framework of the TiO 2 anatase structure. EPR and magnetic susceptibility show that Fe 3+ is in low spin state corresponding to μ B = 1.8 BM. The temperature variation of μ B shows that Fe 3+ is well separated from each other and does not have any antiferromagnetic or ferromagnetic interaction. The evidence of Fe 3+ in TiO 2/Fe 2O 3 alloy is also proved by a new method that is redox titration which is again support by the XPS spectrum.