Characterization of microwave effects on metal-oxide materials: Zinc oxide and titanium dioxide

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• 作者：Satoshi Horikoshi ; Akihiro Matsubara ; Sadatsugu Takayama ; Motoyasu Sato ; Futoshi Sakai ; Masatsugu Kajitani ; Masahiko Abe ; Nick Serpone
• 关键词：Microwaves ; Photocatalyst ; Magnetic field ; Electric field ; 4-Chlorophenol ; ZnO ; TiO₂
• 刊名：Applied Catalysis B: Environmental
• 出版年：2010
• 出版时间：9 September 2010
• 年：2010
• 卷：99
• 期：3-4
• 页码：490-495
• 全文大小：481 K

文摘

The microwave specific effect(s) that can impact a microwave-assisted and photo-assisted reaction occurring on the surface of ZnO or TiO₂ (P-25) particles was (were) examined by comparing the process occurring under rich magnetic field conditions and under magnetic/electric field conditions. The features of the photo-assisted process in the presence of microwaves rich in a magnetic field (H) and an electric field (E) are described on the basis of (i) the degradation dynamics of 4-chlorophenol (4-CP) at ambient temperatures, (ii) the number of OH radicals produced, and (iii) the dielectric properties of the metal oxides (in pellet form). For ZnO, the photoactivity is enhanced by a microwave specific non-thermal (i.e. non-caloric) effect originating from the microwaves’ magnetic field, but decreased by the thermal (i.e. caloric) factor originating from the microwaves’ electric field. Contrary to ZnO, the photoactivity of TiO₂ (P-25) was enhanced by the synergistic effect between the magnetic and electric fields of the microwave radiation. Photocorrosion of ZnO in the aqueous dispersions was negligibly small (<0.05 % ) under UV, MW-EH, and UV/MW-EH irradiation conditions.