Facile In–Situ Construction of Granular–Polyhedral Ag2O–Ag2CO3/Lamellar Bi2O2CO3–Bi2MoO6 Spherical Heterojunction with Enhanced Photocatalytic Activity Towards Pollutants

Bi 2 MoO 6 hollow spheres as precursors, NaOH as etchant, and atmospheric CO 2 as carbon source, a granular–polyhedral Ag 2 O–Ag 2 CO 3 /lamellar Bi 2 O 2 CO 3 –Bi 2 MoO 6 spherical heterojunction material with full–spectrum photocatalytic properties was gained through a one step in–situ precipitation approach. Granular Ag 2 O, polyhedral Ag 2 CO 3 , and lamellar Bi 2 O 2 CO 3 were deposited in–situ on the interior and exterior surfaces of Bi 2 MoO 6 hollow spheres to form nanospheres with a diameter of about 2.8 μm. Using methylene blue (MB) as a model molecule, the effect of NaOH concentration and silver oxide loading on the catalyst activity were investigated to screen out the best catalyst. The results showed that the degradation rate of Ag 2 O–Ag 2 CO 3 /Bi 2 O 2 CO 3 –Bi 2 MoO 6 -1/2–0.1 M was 3.45 and 2.71 times greater than those of Ag 2 O–Ag 2 CO 3 and Bi 2 O 2 CO 3 –Bi 2 MoO 6 -0.1 M, respectively. Meanwhile, the visible light photocatalytic performance of Ag 2 O–Ag 2 CO 3 /Bi 2 O 2 CO 3 –Bi 2 MoO 6 toward MB and antibiotics (tetracycline hydrochloride (TC), chlorotetracycline hydrochloride (CTC)) were also examined. Results confirm that the heterogeneous materials displayed the boosted photocatalytic activity for MB, TC, and CTC. The boosted activity of the composite Ag 2 O–Ag 2 CO 3 /Bi 2 O 2 CO 3 –Bi 2 MoO 6 is attributed to enhance light utilization, increase surface active sites, and formation of effective heterojunction between Ag 2 O–Ag 2 CO 3 and Bi 2 O 2 CO 3 –Bi 2 MoO 6 . Capture experiments have shown the major active species in the photocatalytic degradation system. On the base of capture experiments and photoelectrochemical experiments, plausible photocatalytic mechanism has been postulated.