Efficient visible-light-active ZnO/Cs0.33WO3/g-C3N4 double Z-type heterojunction photocatalyst for rhodamine B photodegradation

Abstract

Developing highly efficient photocatalyst systems for the removal of cancer-causing organic dye substances from polluted water and wastewater is now in high demand because of the growing problem of contaminated water. An affordable technique was employed to create a ternary ZnO/Cs_0.33WO₃/g-C₃N₄ heterojunction nanocomposite with highly efficient and rapid photodegradation capabilities for degrading rhodamine B (RhB) dye. Using visible-light irradiation, the photocatalytic tests revealed that the proposed ZnO/Cs_0.33WO₃/g-C₃N₄ heterojunction nanocomposite is efficiently able to degrade more than 91 % of RhB dye within 15 min, 97.5 % within 20 min, and 99.9 % within 30 min, which is significantly efficient compared to sole ZnO and Cs_0.33WO₃. The kinetic rate constant of RhB photodegradation catalyzed by the ternary ZnO/Cs_0.33WO₃/g-C₃N₄ nanocomposite is assessed to be about 31 times faster than that of Cs_0.33WO₃ and about 3.5 times faster than that of ZnO. The investigation of the photodegradation mechanism suggested that the ternary ZnO/Cs_0.33WO₃/g-C₃N₄ nanocomposite follows a direct Z-scheme mechanism for charge transfer. The creation of a ternary ZnO/Cs_0.33WO₃/g-C₃N₄ heterojunction nanocomposite is valuable for increasing the surface area, strengthening the contact between its components, enhancing absorption capacity of visible light, increasing the generation rate of the photoexcited charge carriers, improving the separation efficiency of photogenerated charge carriers, and reducing their undesired recombination rate. As a consequence, the visible-light-mediated degradation of organic dye contaminants is significantly improved.