A facile synthesis of ZnWO4 nanoparticles by microwave assisted technique and its application in photocatalysis

Characterization and photoactivity of coupled ZnO–ZnWO4 catalysts prepared by a sol–gel method

“…Zinc tungstate (ZnWO 4 ) is a promising material for applications in heterogeneous photocatalysis due to its interesting physical and chemical properties [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Zhu and coworkers reported that ZnWO 4 exhibited relatively high photocatalytic activity for the degradation of aqueous solutions of rhodamine B [25][26][27][28][29][30][31] and methylene blue [30,37] and also for gaseous formaldehyde [26][27][28].…”

“…ZnWO 4 was efficient for the decomposition of salicylic acid [35] and the decoloration of methyl orange [37], malachite green [36,38] and rhodamine 6G [33]. Up to now ZnWO 4 photocatalysts have been synthesized by a variety of different processes including co-precipitation [26], hydrothermal methods [28][29][30][31][32][33], microwave assisted techniques [35,39] and mechanochemical synthesis at room temperature [38]. In the present paper we report the synthesis of ZnWO 4 and ZnO-ZnWO 4 photocatalysts obtained by a novel sol-gel method.…”

Cubic ZnWO4 nano-photocatalysts synthesized by the microwave-assisted precipitation technique

“…However, the blue-shift phenomenon was reported for microwave -assisted synthesized ZnWO 4 [11,24,36].This unsimilar results might be due to difference in the concentration of hydrogenrelated defects in different reports. Although the exact nature of these defects is not yet clear, they may exist in many catalysts that are synthesized by wet-chemical methods, and they can be detected and quantitatively estimated by peaks located at approximately 1385 cm À 1 in the IR spectra [36,37]. High concentrations of hydrogen-related defects propel the mechanism of degradation from chromophore cleavage to deethylation process due to formation of cation vacancy level (to compensate excess positive charge) on the valence band and consequently lowering conduction band level [37,38].…”

“…Furthermore, no shift of the major absorption band during the photocatalytic process, suggested the dominance of conjugated chromophore decomposition instead of the deethylation process [35]. However, the blue-shift phenomenon was reported for microwave -assisted synthesized ZnWO 4 [11,24,36].This unsimilar results might be due to difference in the concentration of hydrogenrelated defects in different reports. Although the exact nature of these defects is not yet clear, they may exist in many catalysts that are synthesized by wet-chemical methods, and they can be detected and quantitatively estimated by peaks located at approximately 1385 cm À 1 in the IR spectra [36,37].…”

Photoluminescence and Photocatalytic Activity in Ca2+ and Dy3+ Co-doped ZnWO4 System

“…However, further research on the ZnWO 4 photocatalytic activities is still indispensable. There are many ways to improve the photocatalytic activity of ZnWO 4 , such as doping ions and coupling with other semiconductors (WO 3 -ZnWO 4 , ZnO-ZnWO 4 , TiO 2 -ZnWO 4 ), but in general, photocatalytic activity depends strongly on the separation efficiency of photo-generated electron-hole pairs [11]. Over the years, a great amount of work has been made to facilitate the electron-hole separation and enhance the photocatalytic activity of ZnWO 4 [12].…”