The solvothermal synthesis of novel β-Bi₂O₃/(BiO)₄(OH)₂CO₃ heterojunctions and its photocatalytic activity

β-Bi₂O₃/(BiO)₄(OH)₂CO₃ composite was first prepared by using NaBiO₃·2H₂O as a precursor via solvothermal method. X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscope, and UV–Vis diffuse reflectance spectrum have been used to characterize the composite material. It was found that the volume ratio of ethanol to water plays a vital role in the formation of (BiO)₄(OH)₂CO₃ and the formation mechanism of β-Bi₂O₃/(BiO)₄(OH)₂CO₃ composite has been investigated in this paper. Additionally, the as-prepared β-Bi₂O₃/(BiO)₄(OH)₂CO₃ heterojunction exhibited superior photocatalytic activity for the degradation of contaminants. 91.1% of Rhodamine B (RhB), 81.6% of Congo red, and 89.4% of tetracycline hydrochloride (TC) can be degraded in 70 min, 180 min and 160 min under the simulated sunlight irradiation, respectively. Furthermore, the apparent rate constant values of β-Bi₂O₃/(BiO)₄(OH)₂CO₃ are approximately 10 times that of β-Bi₂O₃ and about 3 times that of (BiO)₄(OH)₂CO₃. 75.9% of RhB can still be degraded by Bi₂O₃/(BiO)₄(OH)₂CO₃ in the process of third cycling run. The trapping experiments of active species indicated that holes (h⁺) and superoxide radicals (·O₂ ⁻) were the major active species during the degradation process. This study provides new insights into design and synthesis of heterojunction photocatalysts for environmental remediation.