Amino acid-assisted synthesis of ZnO twin-prisms and functional group's influence on their morphologies

ZnO twin-prisms were prepared by a simple solvothermal process with glutamic acid as surface modification agent in ethanol. Compared with the twin-cones that were obtained when glutamic acid was absent, the ZnO twin-prisms have optimized crystallinity with high symmetry, sharp crystal edges and few defects. Probable reaction mechanism between ZnO and glutamic acid was proposed based on our experimental analysis. Then it was verified by a series of comparison experiments by employing glycine, acetic acid and ethylamine as surface modification agents. Our results indicate that both alkaline and acidic groups play an important role on the formation of ZnO twin-prisms, and when either of them was absent, twin-prism structures cannot be obtained. The photoluminescence properties of as-prepared ZnO twin-prisms and twin-cones were also studied.

Research highlightsAmino acid-assisted synthesis of ZnO could optimize crystalline quality and the obtained ZnO has smooth surface, high symmetry, obvious crystal edges and decreased defects. Solvothermal synthesis in absolute ethanol with and without glutamic acid leads to twin-prisms and twin-cones, respectively. Probable interaction mechanisms of amino acid's functional groups to ZnO morphologies were proposed to explain its role in making optimized twin-prisms. The neutralizing reaction between alkaline groups and acidic groups of amino acid would form –NH3+, which could further react with oxygen atoms of ZnO crystals through N–H···O hydrogen bonds. This surface action between organic and inorganic matter may lead to the appearance of ZnO novel morphology.Figure optionsDownload as PowerPoint slide