Promising photocatalytic activity under visible light of ZnWO4 nanocrystals prepared via green synthesis approach

In this work, we report on the biosynthesis of zinc tungstate ZnWO4 nanocrystals using Hyphaene thebaica L. Mart, fruit extracts for visible light photocatalytic application. The structure, nanostructure, and optical properties, as well as the photocatalytic activities of for biosynthesized zinc tungstate on Methylene blue, were investigated in detail. The zinc tungstate was in a pure crystalline phase without the presence of any impurities or secondary phases. The morphological analysis indicates the presence of spherical and uniformly distributed nanoparticles with an average crystallite particle size of 24 nm, and additionally the presence of rod-like particles. The bandgap energy value has been estimated to be 2.8 eV.The photocatalytic activities of ZnWO4 were investigated by the degradation of Methylene blue (MB) under visible light irradiation. A series of reactions, with different initial MB concentrations (1.10−5mol/L, 2.10−5mol/L and 3.10−5mol/L) were implemented using 1 g/L of ZnWO4 catalyst under visible light irradiation. The biosynthesized ZnWO4 achieved an outstanding degradation activity of 98.4% for methylene blue dye after 90 min under visible light emission. The green chemistry was an efficient route to prepare ZnWO4 with high photocatalytic efficiency under visible light irradiation and this improvement is related to oxygen deficiency.