Controlled formation of a flower-like CdWO4–BiOCl–Bi2WO6 ternary hybrid photocatalyst with enhanced photocatalytic activity through one-pot hydrothermal reaction

Abstract

In this study, we synthesized a flower-like CdWO₄–BiOCl–Bi₂WO₆ ternary hybrid (CBB) and CdWO₄–Bi₂WO₆ binary composite in the same system using the same raw materials with different molar ratios and compared their photocatalytic activities. The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) results verify that the transformation of the CdWO₄–BiOCl–Bi₂WO₆ ternary hybrid to the CdWO₄–Bi₂WO₆ binary composite is a topological transformation. Their photocatalytic performances are evaluated by monitoring the degradation of Rhodamine B (RhB). The ternary hybrid (CBB-0.05) shows enhanced photocatalytic activity as compared to pure CdWO₄, BiOCl, Bi₂WO₆, BiOCl–Bi₂WO₆, CdWO₄–Bi₂WO₆ (CBB-0.10) and the other CBB composites. This remarkable enhancement is attributed to the fact that the suitable conduction band (CB) positions in the ternary hybrid can form a cascade structure and the two layered compounds BiOCl and Bi₂WO₆ can epitaxially grow from one phase to another with little strain at the interface; this increases the separation efficiency of charge carriers. In addition, the mechanism of the high photocatalytic activity is discussed based on the photoluminescence (PL) spectra and photoelectrochemical and active species trapping measurements.