Preparation and characterization of mesoporous TiO 2–CeO 2 nanopowders respond to visible wavelength

Abstract

Mesoporous TiO 2–CeO 2 nanopowders responding to visible wavelength were synthesized by using a surfactant assisted sol–gel technique. They were obtained using metal alkoxide precursors modified with acetylacetone (ACA) and laurylamine hydrochloride (LAHC) as surfactant. The samples were characterized by XRD, nitrogen adsorption isotherm, SEM, TEM, and selected area electron diffraction (SAED), respectively. The 95 mol% TiO 2–5 mol% CeO 2 system yielded single anatase phase, however, further addition of the CeO 2 formed cubic CeO 2 structure while anatase TiO 2 decreased. Additions of 5 and 10 mol% CeO 2 increased the surface area, but those of 25, 50, and 75 mol% CeO 2 did not affect it very much. By using this mixed metal oxides system, TiO 2 can be modified to respond to the visible wavelength. The mixed metal oxides had catalytic activity (evaluating the formation rate of I 3 −) about 2–3 times higher than pure CeO 2, while nanosize anatase type TiO 2 materials had no catalytic activity under visible light. The catalytic activity was almost proportional to the specific surface area. The formation rate of I 3 − was much improved by changing the calcination temperature and calcination period. Highest catalytic activity in this study was obtained for the 50 mol% TiO 2–50 mol% CeO 2 nanopowders calcined at 250 °C for 24 h.