Fabrication of Bi12GeO20/Bi2S3 hybrids with surface oxygen vacancies by a facile CS2-mediated manner and enhanced photocatalytic performance in water and saline water

Abstract

A series of biphasic hybrids Bi12GeO20/Bi2S3 containing surface oxygen vacancies (OVs) were constructed through a facile CS2-mediated manner. Microstructural, morphological, optical, and electrochemical features of relevant samples were thoroughly researched by a sequence of analytical techniques. The presence of in-situ generated Bi2S3 phase and simultaneous formation of surface OVs were confirmed in these n-p heterojunction hybrids. As soon as exposed to visible light, as-achieved hybrids provided reinforced photocatalytic removal upon dye Rhodamine B (RhB) and antibiotic tetracycline hydrochloride (TC) in comparison to bare Bi12GeO20, chiefly crediting to augmented visible-light harvesting, efficient spatial separation of charge carriers over interface by n-p heterojunction with well-matched band structures, and presence of sufficient surface OVs. Moreover, reactive Cl species and Cl-contained intermediates were undetectable in saline water, therefore the significantly enhanced catalytic efficiencies in saline water than in water were mainly attributed to different degradation routes by ultraviolet-visible (UV–Vis) absorption, three-dimension excitation emission matrix fluorescence (3D-EEM), and high performance liquid chromatograph-mass (HPLC-MS) spectra, further ascribing to partial consumption of holes by Cl- anions and boosted generation of superoxide (∙O2–) and hydroxyl (∙OH) radicals. Eventually, a reasonable photocatalysis mechanism was proposed in a Z-scheme model by these robust hybrids with favorable recyclability and structural steadiness. This work provided promising Bi12GeO20/Bi2S3 hybrids with appropriate physicochemical properties and reinforced photocatalytic degradation of organic contaminants in saline water without the generation of toxic Cl-containing intermediates.