Synthesis and Characterization of ZnO-ZnS Nanoflowers for Enhanced Photocatalytic Performance : ZnS Decorated ZnO Nanoflowers

Abstract

Metal oxide nanomaterials exhibit high chemical and physical stability, non-toxic nature, and attractive biological properties, hence they are part of one of the most important classes of materials. Zinc oxide is a very commonly used semiconductor, having potential applications in optoelectronics, ultraviolet lasers and detectors, sensors, photovoltaic cells, photo-electrochemical cells and photocatalysts [1] – [5] . Most of these applications involve the ability of ZnO nanostructures to utilize light and effectively separate the photogenerated electrons and holes. Being a wide bandgap semiconductor (3.37 eV) [6] , ZnO is only able to harvest light in the ultraviolet (UV) region. In order to make sure that the visible light is also effectively utilized, the most common strategy is to functionalize the surface of ZnO with other semiconductors. For this reason, researchers have successfully functionalized the surface of ZnO nanostructures with narrow bandgap semiconductors such as CdS [7] , Cu 2 O [8] , CdSe [9] , CdTe [10] – [12] , etc. which act as sensitizer to absorb light with a greater spectrum range [13] . Similarly, ZnO has also been incorporated with wide bandgap semiconductors such as TiO 2 , SnO 2, and ZnS in order to improve utilization of ultraviolet (UV) spectrum of solar light. Fabrication of ZnO-TiO 2 architectures resulted in an increased light absorption, higher photo-induced current, and more effective charge separation [14] , [15] . Synthesis of ZnO coupled with SnO 2 produced unique luminescence properties and improved photocatalytic performance [16] – [18] .