ZnO nanorods decorated with carbon nanodots and its metal doping as efficient photocatalyst for degradation of methyl blue solution

Abstract

Abstract In this study, we report a facile and green chemistry technique to produce ZnO nanorods decorated with carbon nanodots (C-dots) to yield good photocatalytic for degradation of methyl blue. C-dots dispersed solution was obtained via simple carbonization of cassava peels at low temperature followed by ageing process for 6 days in absolute ethanol. The ZnO/C-dots heterostructure has been prepared by spin-coating C-dots dispersed solution onto ZnO nanorods surface. The impact of doping metal such as Co and Mn and the attachment of C-dots nanoparticles onto the surface of ZnO nanorods on their morphology, optical properties and photocatalytic activity were examined. The experimental results reveal that C-dots have successfully been attached onto the surface ZnO nanorods through strong physical interaction between C-dots and ZnO without modifying the morphology, surface area and crystallinity of ZnO nanorods. However, the energy bandgap of ZnO slightly decreases. This condition turns into increasing the charge separation efficiency of its electron-hole pairs which significantly enhances the visible light photocatalytic activity of the sample. The photodegradation rate of methyl blue was found to depend on the number of layers of C-dots. The Co doped ZnO nanorods coated with 4 layers C-dots particles was found to effectively degrade methyl blue solution compared to pristine ZnO nanorods. It is believed that high photocatalytic activity of metal doped ZnO/C-dots nanocomposite under UV light irradiation originates from their outstanding unique properties and the stimulated separation of photogenerated electron-hole pairs based on C-dots.