Structure and photocatalytic properties of Bi 25 FeO 40 crystallites derived from the PEG assisted sol-gel methods
- PDF / 317,139 Bytes
- 7 Pages / 432 x 648 pts Page_size
- 16 Downloads / 132 Views
Structure and photocatalytic properties of Bi25FeO40 crystallites derived from the PEG assisted sol-gel methods Shundong Bu, Dengrong Cai, Jianmin Li, Shengwen Yu, Dengren Jin and Jinrong Cheng School of Material Science and Engineering, Shanghai University, Shanghai, China ABSTRACT Sillenite Bi 25 FeO 40 crystallites have been fabricated via a sol-gel approach. X-ray diffraction results show that single-phase Bi 25 FeO 40 can be synthesized at the annealing temperature of 600 o C with the help of PEG additive. The amount of additives and the annealing temperature has great effects on the formation of phase pure Bi 25 FeO 40 crystallites. The morphologies of Bi 25 FeO 40 crystallites were observed by SEM techniques. UV-vis diffuse reflectance spectroscopy indicated the good visible light absorption of Bi 25 FeO 40 crystallites. The photo-catalytic activity of Bi 25 FeO 40 powders was evaluated by the degradation of methyl orange solution assisted by H 2 O 2 under UV-Vis light and Vis-only light irradiation, which suggested that Bi 25 FeO 40 crystallites are potential photocatalytic materials. INTRODUCTION Akira Fujishima discovered that water was photocatalytic decomposed at a TiO 2 electrode in 1972 [1]. Since then, semiconductor photocatalyst like TiO2 is widely used to degrade organic pollutant and produce hydrogen as clean energies. Nowadays, TiO 2 is the most interesting catalytic materials due to its high activity , chemical stability and nontoxic. However, the band gap of TiO 2 is 3.2 eV so that it can only respond under ultraviolet irradiation, which means plenty of sunlight including visible light and infrared ray was useless for it. Therefore, many new semiconductor photocatalytic materials with low energy gap appears. Sillenite material is one of the novel photocatalysts. Due to its unique BiO heptacoordination in the crystal structure [2], sillenite compounds , with the general formula Bi 12 MO 20 (M=Ge, Ti, Ga, Fe, Bi, V, etc.), has been reported the high photocatalytic property and photo-conductivity, such as Bi 12 SiO 20 [3], Bi 12 GeO 20 [4], Bi 12 TiO 20 [5] and Bi 24 Ga 2 O 39 [6] . It is reported [7] that Bi 25 FeO 40 also has the structure of sillentite with M=Bi 0.5 Fe 0.5 . The umbrella-like Bi 3+ O 3 groups [8] in Bi 25 FeO 40 crystal is also considered to eliminate the recombination of electron–hole pairs and its photocatalyst behavior is worth looking forward to. In this paper, single-phase Bi 25 FeO 40 crystallites were fabricated by PEG-assisted sol-gel method. The morphology and the photocatalytic activity of Bi25 FeO 40 powder is also reported.
149
EXPERIMENT The sillenite Bi 25 FeO 40 were synthesized by sol-gel method. The chemicals used in the experiment is bismuth nitrate [Bi(NO 3 ) 3 ·5H 2 O], ferric nitrate [Fe(NO 3 ) 3 ·9H2O], glycol [(HOCH 2 ) 2 ] as solvent and polyethylene glycol (PEG) [HO(CH 2 CH 2 O) n H] as additive. All the chemicals above were analytical grade purity. Firstly, 0.005 mol Bi(NO 3 ) 3 ·5H 2 O and 0.0002 mol Fe(NO 3 ) 3 ·9H 2 O were dissolved in glycol o
Data Loading...
