Synthesis and characterization of Ag/Ce1-XBiXZnO composites hosted α-β/Bi2O3 as highly efficient catalysts for degradation of cationic and anionic dyes

Removal of organic impurities from wastewater has become concern for humanity. Herein, to improve the Ag/ ZnO performance in degradation of organic dyes catalyst was modified by Ce and Bi in order to form an interface or heterojunction between catalyst component, which can suppress the rapid e (-)/h(+/-) recombination in ZnO. Where, Ag/Ce1-XBiXZnO composites (x = 0, 0.1, 0.3, and 0.5) were synthesized using CTAB assisted hydrothermal/deposition method. Ag/Ce1-XBixZnO catalysts exhibited exceptional photocatalytic activity for the degradation and mineralization of cationic and anionic dyes under UV and visible light irradiation. The trend in the photocatalytic degradation of dyes using Ag/Ce1-XBiXZnO depends on amount of Bi doped. The maximum photodegradation of the Rhodamine dye was achieved up to 99.9% using Ag/Ce0.1Bi0.9ZnO photocatalyst with absolute mineralization efficiency 77.9% however, Ag/Ce0.3Bi0.7ZnO showed superior photocatalytic activity in degradation of Indigo with 99.8 % with absolute mineralization efficiency 64.6%. The characterization results of various techniques (viz., XRD, XPS, H2TPR, PL and DRS) revealed that the incorporation of different amount of Bi in the Ag/Ce1-XBiXZnO catalysts is most beneficial for decreasing band gap (2.48-2.58 eV), creation of oxygen vacancy, improvement of Ag dispersity, and change the ratios of different phases: alpha-/beta-Bi2O3, CeO2/Ce2O3, Ag/ AgOy on the catalyst surface. It is also proposed that the lower band gap of Ag/Ce1-XBiXZnO catalysts and the creation of oxygen vacancies provide methods to suppress the rate of recombination of photoinduced electrons and holes as was confirmed by PL analysis. In addition, high resolution transmission and scanning electron microscopies analyses establish the formation heterojunctions between composite phases. The change of the mentioned above physicochemical characteristics of Ag/Ce1-XBiXZnO catalysts by Bi doping may be affected on their capabilities to generate and transform more e- and h+ to O-2 and H2O respectively, to create center dot O-2, and center dot OH active radicals for dyes degradation. Trapping experiment indicates that center dot O-2, and center dot OH radicals have significant role in the degradation of RhB over Ag/Ce0.1Bi0.9ZnO. However, center dot O-2 radicals were the major species responsible for the degradation of Indigo dye over Ag/Ce0.3Bi0.7ZnO. Here, it is suggested that the ratio of photogenerated center dot O-2/center dot OH by Ag/Ce1-XBiXZnO depends also on the amount of Bi in the catalysts, which results in the observed differences in their catalytic performances. The reusability test demonstrated that Ag/Ce1-XBiXZnO catalysts have a decent stability.