Nano-island-like heterojunction of nitrogen-doped carbon quantum dots anchoring on titanium oxide nano sheets@Cu2O for enhancing visible light-driving photocatalytic degradation of methyl orange

Abstract

Cu2O and TiO2 are promising for photocatalysis owing to their lower cost and excellent performance. Unfortunately, the efficiency of light utilization by Cu2O and TiO2 is still low. Herein, the nano-island-like heterojunction of nitrogen-doped carbon quantum dots anchoring on titanium oxide nano sheets@Cu2O (NCQDs/TNSs@Cu2O) was synthesized through the hydrothermal and chemical precipitation process and its photocatalytic performance was systematically characterized. Benefiting from the unique heterojunction, NCQDs/TNSs@Cu2O exhibited a superior photocatalytic performance. High-resolution transmission electron microscopy showed that NCQDs/TNSs nanoclusters were decorated on Cu2O nanoparticle surface and formed heterojunctions. The UV–Vis-DRS spectra indicated that NCQDs/TNSs@Cu2O exhibited the strong adsorption peaks between 400 and 650 nm. Under simulated sunlight irradiation, NCQDs/TNSs@Cu2O exhibited excellent photocatalytic degradation performance on methyl orange. For example, the degradation was completed within 20 min and the photo-degradation capacity of NCQDs/TNSs@Cu2O remained 90.1 % after four recycling cycles. Furthermore, the potential mechanism for the photo-induced degradation was proposed based on the active substances identified through the electron spin resonance. Conclusively, this study provides a novel perspective on the role of NCQDs and prepares the way for the design of the biomass-based photocatalyst.