Ag 2 WO 4 Polymorphs: Easily Synthetized and Highly Efficient for Antibiotics Degradation

The transition metal tungstates is an inorganic oxides family are widely used in many applications such as environmental purification, clear fuel production, etc. [1,2] Among the metal tungstates, the Silver tungstate (Ag2WO4) is applied in various fields like photocatalysts, sensors, antibacterial agents, etc [2,3]. In this work, different Ag2WO4 polymorphs; alfa- (stable); and beta- and gamma- (metastables); were synthesized by a facile and low cost effective co-precipitation method. The synthesized materials were characterized by XRD, FT-IR spectroscopy, and SEM analysis. The XRD pattern reveals the formation of each Ag2WO4 structure. The FT-IR and Raman analysis confirms the presence of Ag-O and W-O bonds in Ag2WO4 crystals. The morphologies of the as-synthesized Ag2WO4 were analyzed by SEM. Other than that, to the best of our knowledge, the reports on the photocatalytic properties of all Ag2WO4 polymorphs are obtained rarely. Under UV-Vis irradiation, the photocatalytic action of each polymorph was tested for the degradation of amiloride and the photoactivity performances and degradation reactions were evaluated. Beta- Ag2WO4 showed the best photocatalytic activity among the three kinds of samples, 100 % degradation within 35 min. In particular, the metastable polymorphs exhibit the highest photocatalytic activity when compared to more stable polymorphs, due to more active surfaces. All polymorphs were a durable and stable photocatalyst during recycling experiments. The present work contributes to a deeper understanding of metastable photocatalysts with high photocatalytic activity, in order to address future demands on environmental remediation.