A novel natural sunlight active photocatalyst of CdS/SWCNT/CeO2 heterostructure: In depth mechanistic insights for the catalyst reactivity and dye mineralization

Abstract

A conventional type II heterostructure based on CdS/SWCNT/CeO2 was successfully prepared via a modified co-precipitation and hydrothermal method. The as-prepared heterostructure was characterized via UV–Vis, Fluorescence, XRD, XPS and TEM. The morphology of the heterostructure showed spherical nanoparticles with a particle size of 5.1 nm for CdS/CeO2 on the SWCNT. These properties were translated into remarkable enhancement in the photodegradation of Rhodamine 6G (R6G) dye as a model pollutant for textile and food stuff industries under natural solar radiation. The photo-experiments showed an enhanced photocatalytic activity of CdS/CeO2 and CdS/SWCNT/CeO2 to be 79.3% and 86.4% respectively which are two-fold much greater than that of bare CeO2 NPs (36.6%). Also, the calculated photonic efficiencies (ζ) were found to be 11.7%, 39% and 54.5% for CeO2, CdS/CeO2 and CdS/SWCNT/CeO2 nanostructures respectively. Total organic carbon (TOC) was used to further estimate the mineralization capability of the heterostructure (94% TOC Removal). Furthermore, the band alignment of CdS/SWCNT/CeO2 heterostructure was determined via Mot-Schottky plots and Valence and Core-Level X-ray Photoelectron Spectroscopy, which provided a deep insight about the photodegradation efficiency. For in-depth understanding what happens during the photodegradation, the detection of reactive oxidative species (ROS) was investigated by the trapping experiments.