Synthesis of ZnO and Au tethered ZnO pyramid-like microflower for photocatalytic degradation of orange II

Highlights: ► Pyramid-like microflower structured zinc oxide (ZnO) nanoparticles were successfully prepared with different morphologies using hydrothermal synthesis at different temperatures. ► Then Au tethered ZnO pyramid-like microflower (Au–ZnO) was prepared by the reduction of HAuCl4 in the presence of β-D-glucose as stabilizer. ► The Au–ZnO microflower catalyst shows the better efficiency of decomposing orange II dye under visible light illumination compared with pure ZnO microflower. It can be attributed to Au nanoparticles on the ZnO surface serving as electron sinks to promote the photocatalytic ability. - Abstract: Pyramid-like microflower structured zinc oxide (ZnO) nanoparticles were successfully prepared under hydrothermal processes. Then Au nanoparticles were tethered on ZnO pyramid-like microflower (Au–ZnO) by the reduction of HAuCl4 in the presence of β-D-glucose as stabilizer. The materials were well characterized by different analytical techniques and they could be potentially utilized for the photocatalytic degradation of orange II in the visible region. SEM images reveal that the ZnO microflowers are well formed at 100 °C and on increasing the temperature ZnO nuclei typically grow in the direction of c-axis alone due to typical increase in the dipole moment along that direction. TEM image shows that gold nanoparticles are tethered on the ZnO surface. A possible mechanism for the formation of ZnO and Au–ZnO microflowers has been also discussed.