Temperature impact on the morphological evolution of nitrogen-doped carbon quantum dot-decorated zinc oxide and its influence on highly efficient visible-light photocatalyst

Abstract

Nitrogen-doped carbon quantum dot-decorated zinc oxide (ZnO/NCQD) was synthesized using a hydrothermal process under various thermal conditions. XRD (X-Ray Diffractometer) and field emission-scanning electron microscopy (FE-SEM) confirmed the crystal structure of wurtzite, and there was a morphological evolution from a hexagonal nanorod to a nanoflower. Simultaneously, the optical properties and photocatalytic activity were investigated using UV–visible diffuse reflectance, photoluminescence, and UV–vis spectrophotometers. The presence of NCQD on the ZnO surface lowers the bandgap energy and shifts the absorbance toward visible light. As a result, it enhanced the photocatalytic activity and efficiency of ZnO/NCQD, achieving approximately 80% methylene blue (MB) degradation in 15 min under visible light. It was concluded that the hydrothermal temperature played a role in the particle growth of the ZnO/NCQD and affected the optical and photocatalytic properties. Therefore, the fabricated ZnO/NCQD has excellent potential for photocatalytic dye degradation.