Few-layered Bi 4 O 5 I 2 nanosheets enclosed by {1 0−1} facets with oxygen vacancies for highly-efficient removal of water contaminants

Few-layered Bi 4 O 5 I 2 nanosheets (FL-Bi 4 O 5 I 2 ) were synthesized by intergrowth with Bi 2 O 2 CO 3 under room temperature. The photoactivity of FL-Bi 4 O 5 I 2 was 2.5 and 9.5 times higher than that of Bi 4 O 5 I 2 nanoflakes (NF-Bi 4 O 5 I 2, about 30 nm thickness) and standard visible-light-driven N-TiO 2, respectively. Moreover, FL-Bi 4 O 5 I 2 exhibited a wide pH application range (3.0 – 10.0) and excellent photostability. The characterization results showed FL-Bi 4 O 5 I 2 was consisted of 5 – 8 layers with thickness of 4 – 7 nm and enclosed by {1 0 − 1} facets. The ultrathin characteristics could accelerate the charge transfer to the surface due to the shortened transport distance. Compared to NF-Bi 4 O 5 I 2, surface oxygen vacancies and the more negative CB potential were formed on FL-Bi 4 O 5 I 2. The photogenerated electrons were confirmed to be captured by surface oxygen vacancies to effectively reduce surface adsorbed O 2 into HO 2 • /O 2 •–, leaving more h + to oxidize organic pollutants. This process was further facilitated by the more negative CB potential of FL-Bi 4 O 5 I 2, resulting in the highly efficient removal of pollutants.