Morphology evolution of one-dimensional ZnO nanostructures towards enhanced photocatalysis performance

One-dimensional ZnO nanostructures with various morphologies including nanotubes, nanobelts, solid fibers, nanochains, and porous nanotubes were created through adjusting the parameters in single-spinneret electrospinning and calcination processes. The evolution of morphology depended strongly on the viscosity of precursor solutions and calcination process. Namely, the nanotube was fabricated via a two-step calcination process while the nanochain and solid fiber were created using a one-step calcination process. The nanotubes consisted of small ZnO nanoparticles. Furthermore, the nanobelt was fabricated when much more zinc precursor was added to increase the viscosity of the precursor solution. A possible mechanism based on Kirkendall effect and the decomposition of polyvinyl pyrrolidone was proposed to explain the formation of ZnO nanotubes and other one-dimensional structures. The photocatalytic activity of these ZnO samples for the degradation of Rhodamine B under ultraviolet light was investigated, and nanobelts showed the best degradation efficiency. Besides, the deposition of Au nanoparticle on ZnO nanobelts can further enhance the photocatalytic performance due to the formation of ohmic contact.