Hydrothermal synthesis of ZnO nanostructures for environmental applications: the role of different supporting ligands

In this study, an effective approach was presented to design ZnO powders that can be used in environmental applications, especially in the degradation of water pollutants. As far as we know, in addition to hexamethylenetetramine frequently used in the hydrothermal synthesis of ZnO powders, hexylamine, hexamethylenediamine, and monoethanolamine supporting ligands were used for the first time in the literature. Supporting ligands having chains at different ends and lengths allowed the production of ZnO powders with different surface morphologies containing microstructures and nanosheet formations. The monoethanolamine ligand resulted in the improvement of structural properties and the progression of crystallization. Hexylamine ligand played a triggering role in increasing the degradation rate and shortening the degradation time of the methylene blue dye. As a result, the supporting ligands used in the synthesis of ZnO powders have a strong effect on the surface morphology, structural, optical, and photocatalytic properties. Especially, ZnO–hexamethylenetetramine–hexylamine is a suitable candidate for environmental applications. We believe that our synthesis way can compete with the approaches of doping different elements to ZnO powders or forming heterostructures frequently applied in the literature.