6TH International Congress on Technology - Engineering - Kuala Lumpur3 - Malaysia (2018-07-19)

Synthesis Of Fe2o3@tio2 Core-shell Nanocomposite By Microwave Irradiation With Enhanced Photocatalytic Activity Under Visible Light

TiO2@Fe2O3 core-shell nanocomposites (NCs) were prepared by microwave (MW) irradiation method within short reaction time. The presence of Ti 2p peak in XPS analysis and the peak at 2? = 25.3 obtained by XRD confirmed the successful synthesis of the Fe2O3@TiO2 nanocomposite. TEM analysis corroborated the formation of the TiO2 shell. Photodegradation of methylene blue was performed to verify the visible light driven photocatalytic efficiency of the Fe2O3@TiO2 core-shell nanocomposites. Keywords: Heterostructure, Microwave, Photocatalysis. Introduction: TiO2 is being used as promising photocatalyst for its non-toxicity, high oxidizing power, chemical stability, as well as low cost [1]. Commercial TiO2 shows lower catalytic performance in the visible region due to its wide band-gap energy, though it acts as an efficient photocatalyst under UV irradiation [2]. The Fe2O3 has been chosen, as a sensitizer, to modify the optical activity of TiO2 in the visible region. Experimental section: 0.2 g Fe2O3 nanoparticles were dispersed in 20 mL ethanol and sonicated for 10 minutes. 10 mL water and 10 mL NH4OH (pH=12.7) were added into the Fe2O3 dispersed solution and assigned as solution A. Solution B was prepared by dissolving 0.132 mL, 0.265 mL, 0.520 mL of Ti(OBu)4 in 60 mL ethanol. Solution B was added to solution A followed by microwave irradiation at 50 °C for 5 min. The resulting TiO2@Fe2O3 NCs were centrifuged and dried in vacuum oven. Results: XRD was used to reveal the crystallinity of the synthesized nanocomposites. Fig. 1 represents the XRD patterns of Fe2O3, TiO2, and Fe2O3@TiO2 nanocomposites. Fig. 1(b) is the XRD pattern of Fe2O3@TiO2?0.520 before calcination, and no characteristic peak of TiO2 exist, but the peak intensities of Fe2O3 decreases. It indicates that the as-formed TiO2 shell is amorphous. Figure. 1: XRD patterns of (a) uncoated Fe2O3, (b) amorphous Fe2O3@TiO2?0.520, (c)?(d) Fe2O3@TiO2?0.520 calcined at 450 °C, and 500 °C, (e)?(g) Fe2O3@TiO2?0.520, uncoated Fe2O3, prepared TiO2, respectively which were calcined at 600 °C. Figure. 2: XPS spectrum of (a) uncoated Fe2O3, (b) prepared TiO2, (c) Fe2O3@TiO2?0.132, (d) Fe2O3@TiO2?0.265, and (e) Fe2O3@TiO2?0.520 NCs. Fig. 2 is the XPS survey spectra and it shows that the intensity of Fe 2p decreases and Ti 2p peak increases with the escalation of TiO2 precursor concentration, predicting the gradual increasing of TiO2 shell thickness. Fig. 3 exhibits the TEM images of the bare Fe2O3 and synthesized Fe2O3@TiO2 nanocomposites in different magnification. The original size of pure Fe2O3 was 12~75 nm, and size increases after the formation of 2.2~6.4 nm TiO2 layer. Figure. 3: TEM images of (a) uncoated Fe2O3, (b) Fe2O3@TiO2?0.132, (c) Fe2O3@TiO2?0.265, and (d) Fe2O3@TiO2?0.520 nanocomposites. Figure. 4: Investigation of photocatalytic activity under visible light; (a) uncoated Fe2O3, (b) prepared TiO2, (c) Fe2O3@TiO2?0.132, (d) Fe2O3@TiO2?0.265, and (e) Fe2O3@TiO2?0.520 nanocomposites. The heterogeneous Fe2O3@TiO2 NC inhibits electron-hole recombination, and induces greater photochemical quantum yield. As a result, it shows better photocatalytic activity under the visible light illumination compared to uncoated Fe2O3, which is shown in Fig. 4. References: [1] Zhiqiao H, Qiaolan C, Huiying F, Gaohua S, Jianping Q, Shuang S, Jianmeng C. Photocatalytic activity of TiO2 containing anatase nanoparticles and rutile nanoflower structure consisting of nanorods. J. Environ. Sci. 2013 Apr 11; 25(12):2460–2468. [2] Xiao Z, Yaping X, Haoxin C, Jinxue G, Alan M, Chunfang L. One-dimensional mesoporous Fe2O3@TiO2 core-shell nanocomposites: Rational design, synthesis and application as high-performance photocatalyst in visible and UV light region. Appl. Surf. Sci. 2014 Aug 17; 317:43–48.
Md. Obaidullah, Takeshi Furusawa, Masahide Sato, Noboru Suzuki