1. Preparation of Pt-loaded WO3 with different types of morphology and photocatalytic degradation of methylene blue
- Author
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Aya Fujii, Takeshi Hashishin, Zhicong Meng, Kazuo Kojima, Chihiro Yogi, and Tomoe Sanada
- Subjects
Aqueous solution ,Materials science ,Hexagonal phase ,Mineralogy ,Surfaces and Interfaces ,General Chemistry ,Triclinic crystal system ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Phase (matter) ,Reagent ,Specific surface area ,Materials Chemistry ,Photocatalysis ,Nuclear chemistry ,Monoclinic crystal system - Abstract
Four types of shape and crystal structure-controlled WO 3 (normal: N-WO 3 , disk: D-WO 3 , cuboid: C-WO 3 , hexagonal plate: H-WO 3 ) were synthesized from starting reagent of (NH 4 ) 10 W 12 O 41 ·5H 2 O by pyrolysis (N-WO 3 ), precipitation (D-WO 3 ) and hydrothermal (C-WO 3 and H-WO 3 ) methods. N-WO 3 and D-WO 3 have monoclinic and triclinic mixed phases each. C-WO 3 has monoclinic phase, and H-WO 3 has hexagonal phase mixed with monoclinic phase. Pt particles-loaded WO 3 (Pt/WO 3 ) was prepared to improve photocatalytic activity. Among four types of Pt/WO 3 , Pt/C-WO 3 shows the highest photocatalytic activity for the degradation of methylene blue (MB) under visible-light irradiation, and photocatalytic activity decreases in the order Pt/C-WO 3 ≈ Pt/H-WO 3 > Pt/D-WO 3 ≫ Pt/N-WO 3 . The MB degradation ability per unit specific surface area after visible-light irradiation for 6 h decreases in the order Pt/H-WO 3 ≫ Pt/C-WO 3 > Pt/D-WO 3 > Pt/N-WO 3 , suggesting that with similar specific surface area of WO 3 , the hexagonal phase is more favorable for MB degradation than the monoclinic phase. This is believed to be due to the high MB adsorption ability of the hexagonal phase. Scavengers for OH radicals, holes and excited electrons were added to MB aqueous solution to investigate the degradation mechanism of MB on each Pt/WO 3 . In the case of Pt/C-WO 3 and Pt/H-WO 3 , OH radicals and holes were the main oxidants in the degradation process of MB, where OH radical ( OH) generation could be attributed to oxidation of H 2 O by holes.
- Published
- 2015