Structural strategy to enhance the quantum and photocatalytic efficiency of ZnO quantum dots by incorporation of interface states

Abstract

ZnO quantum dots (QDs) are potential candidates for high-efficiency emitters and photocatalysts. High efficiency demands high recombination of carriers, while high photocatalytic efficiency demands charge carrier separation. Here, we report an unexplored approach for achieving these opposite properties simultaneously by incorporating interface states in the ZnO QDs through a new strategy. We have used TEOS with Zinc acetate as synthesis precursors to prepare SiO2 encapsulated 5–6 nm ZnO QDs (ZnO@SiO2 QDs). X-ray photoelectron spectroscopy (XPS), FTIR and negative photoconductivity test confirmed the formation of interface states due to Zn − O − Si bonds between the SiO2 matrix and ZnO quantum dots. The ZnO@SiO2 QDs possess remarkable photocatalytic dye degradation properties, e.g., stability, efficiency and recyclability that outperform even the uncoated and commercially available ZnO beside high quantum yield varying between 46.1 % to 56.4 %, simultaneously. The photocatalytic mechanism has been further verified using the radical scavenger test. Thus, the work outlines designers' material design perspectives and discusses the detailed photophysical mechanisms for guiding the development of next-generation high-efficiency emitters and photocatalysts.