Cadmium and bismuth dopants’ synergistic effect on the photocatalytic dye degradation potential of ZnO/CdO

Abstract

Currently, several dyes are used in day-to-day activities, and their toxicity poses significant challenges to human health. In this study, the high negative conduction and positive valence band edge of zinc oxide (ZnO) were modified through the inclusion of Cd and Bi dopants as localized mid-gap states that synergistically diminish the electron-hole recombination. The combustion approach has been used to uniformly distribute the dopants in ZnO’s crystal lattice. The TGA-DTA analysis confirmed 490 °C as the precise calcination temperature to achieve a pure and stable ZnO and Cd-Bi co-doped ZnO/CdO (CBZ) heterostructure. The homogeneous Cd and Bi dopant distribution was verified by EDS elemental mapping investigation. The FESEM and TEM images confirm the sheet-type morphology with several nanoscale-sized agglomerated particles on the surface. The uniform dopants’ inclusion was also confirmed by intensity reduction and occurrence of deep-level emission bands in the visible regions of the PL spectrum. The lower solubility of Cd in the ZnO crystal lattice compared to Bi was confirmed by the CdO independent peak development on the XRD pattern analysis. Compared to ZnO ( k = 0.044 min −1 ), the optoelectrical and dye degradation potential improvement for CBZ ( k = 0.081 min −1 ) was confirmed.