Controllable synthesis of ZnO hierarchical architectures and their photocatalytic property

• Three ZnO hierarchical architectures were synthesized through a facile solution route, employing trisodium citrate as structure-directing agent.
• The influence of the citrate concentration on ZnO microstructure was studied.
• The possible formation mechanisms of three ZnO hierarchical architectures were proposed.
• The photocatalytic properties of the samples were evaluated by photodegradation reaction of methylene blue under UV irradiation.

A facile solution route to synthesize ZnO hierarchical architectures was carried out employing trisodium citrate as structure-directing agent. Three different morphologies and crystal phase samples, including double-layer hexagonal prism ascribed to wurtzite ZnO (JCPDS No. 36-1451), porous microspheres ascribed to an unusual ZnO phase (JCPDS No. 21-1486) and smooth solid amorphous zinc citrate microsphere, were obtained. FESEM, TEM, XRD and FT-IR spectroscope were used to investigate the structure character of the products. The influence of the citrate concentration on ZnO microstructure was studied. It was found that the citrate concentration played a key role in evolution of the morphology and crystal phase. On the basis of experimental results, a possible formation mechanism of the ZnO hierarchical nanostructures was proposed. Photocatalytic property of the samples was evaluated by photodegradation reaction of methylene blue (MB) under UV irradiation. Among these products, double-layer hexagonal prism samples exhibited the highest photocatalytic activity.