Investigation on visible-light photocatalytic degradation of 2,4-dichlorophenoxyacetic acid in the presence of MoO3/ZnO nanorod composites

Nanoscaled MoO3 particles loaded on ZnO nanorods (ZnO NRs) were synthesized via a hydrothermal-precipitation method. X-ray diffraction, field emission-scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV–vis absorption and photoluminescence studies were used to characterize the structures, morphologies and optical properties of the composites. The results showed that pure orthorhombic phase of α-MoO3 nanoparticles with average sizes of 15–21 nm were well dispersed on the surface of ZnO NRs. The MoO3/ZnO NR composites also showed high charge separation efficiency and ·OH generation ability as evidenced by their photoluminescence spectra. The photocatalytic studies revealed that the MoO3/ZnO NRs showed superior visible-light degradation rate for herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) compared with the pure ZnO NRs. Such enhancement might be attributed to the high separation efficiency of photogenerated electron–hole pairs based on the cooperative roles between bi-components of MoO3 and ZnO NRs. The photocatalytic studies also showed that various parameters such as the MoO3 content in the composite, MoO3/ZnO NRs amount, initial 2,4-D concentration and solution pH exerted their individual influence on the 2,4-D degradation. Moreover, the MoO3/ZnO NRs could be easily recovered and reused due to their one-dimensional nanostructural property.

Figure optionsDownload high-quality image (93 K)Download as PowerPoint slideHighlights
► MoO3/ZnO nanorods were newly synthesized by a hydrothermal-precipitation method.
► MoO3 showed visible-light absorption ability and a redshift for the composites.
► Highly enhanced visible-light degradation of 2,4-D was realized.
► The composites were efficiently separated charge carriers to form more ·OH radicals.
► A cooperative photocatalytic mechanism for the composites was also discussed.