Modified 2D-2D ZnIn2S4/BiOCl van der Waals heterojunctions with CQDs: Accelerated charge transfer and enhanced photocatalytic activity under vis- and NIR-light

Broadening the range of light absorption and inhibiting charge carrier's recombination are vital to improving photocatalytic activity. In this study, a novel full spectrum light-driven carbon quantum dots (CQDs) modified 2D-2D ZnIn2S4/BiOCl van der Waals (VDW) heterostructures were prepared by a facile hydrothermal method. It exhibits remarkable degradation efficiency for removing various antibiotics from water (i.e. tetracycline (TC), ciprofloxacin (CIP) and oxytetracycline (OTC) under visible and near-infrared (NIR) light. The enhancement of photocatalytic performance is due to the 2D-2D VDW heterostructures and CQDs not only accelerate the interfacial charge separation and transfer but also provide massive reactive canters to facilitate degradation reaction. Besides, the optical absorption capacity of CQDs modified 2D-2D ZnIn2S4/BiOCl VDW heterostructures are obviously enhanced because of the up-conversion photoluminescence (UC-PL) properties of CQDs. Furthermore, the degradation process of TC is assessed by three-dimensional excitation-emission matrix (3D-EEMs) and liquid chromatography-tandem mass (LC-MS/MS) spectrometry analysis. Active species trapping experiments and electron spin resonance (ESR) testify that center dot O-2(-), center dot OH, and holes play a crucial part in the photocatalytic degradation process. This work affords a new promising approach for CQDs modified 2D/2D VDW heterojunction with enhanced photoactivity in organic pollutant degradation for full spectrum light utilization. (C) 2019 Elsevier Ltd. All rights reserved.