Structure of flower-like hierarchical CdS QDs/Bi/Bi2WO6 heterojunction with enhanced photocatalytic activity

Abstract

A flower-like hierarchical CdS QDs/Bi/Bi₂WO₆ heterojunction photocatalyst was synthesized via an in situ reduction and deposition process. The samples were systematically characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), nitrogen absorption–desorption isotherms, photoelectrochemical measurements and photoluminescence spectroscopy (PL). The results indicate that plasmonic Bi nanoparticles as the electron-conduction mediator with size of 10 nm promote charge transfer effectively between the CdS nanoparticles and Bi₂WO₆ nanosheets. The photocatalytic performance tests show that the CdS QDs/Bi/Bi₂WO₆ composite exhibits extraordinarily enhanced photocatalytic activity than pure Bi₂WO₆, Bi/Bi₂WO₆ and CdS QDs/Bi₂WO₆ for the photodegradation of Rhodamine B and formaldehyde. The superior photocatalytic performance of the CdS QDs/Bi/Bi₂WO₆ composite is attributed to its improved visible light absorption property by coupling CdS QDs with plasmonic Bi and also to the efficient charge transfer of the metallic Bi nanoparticles.