Enhanced photocatalytic performance over Bi4Ti3O12 nanosheets with controllable size and exposed {001} facets for Rhodamine B degradation

Single-crystalline Bi4Ti3O12 nanosheets with rectangular shape and exposed {0 0 1} facets were successfully synthesized via a sol-gel hydrothermal process for the first time. Their average side lengths were around 100 and 150nm, respectively, and thickness similar to 20 nm. As a result, the Bi4Ti3O12 nanosheets reached as high as 79.2% of photodegradation efficiency of Rhodamine B (6 ppm of initial contentration) under 90 mm of sunlight irradiation, which was 3 times that of conventionally calcined Bi4Ti3O12. The synthesized nanosheet catalyst also exhibited high reusability for the photodegradation reaction due to the chemical stability of its single crystalline structure. Moreover, photodegradation efficiency of the Bi4Ti3O12 nanosheets increased as decreasing Rhodamine B concentrations in the range of 6-20 ppm or pH values in the range of 3.1-11.2. Addition of 0.1 M SO42- to reaction solution increased almost 6% of photodegradation efficiency of Bi4Ti3O12 nanosheets under 90 min of illumination. These results demonstrate the superiority of the novel synthetsis technique for preparing bismuth titanate photocatalyst. The much-enhanced photocatalytic performance of Bi4Ti3O12 nanosheets is attributed to their increased active surface sites, efficient separation and transfer of photogenerated charge carriers and greatly suppressed recombination rate of e(-)/h(+) pairs, arising from their large specific surface area, small particle size, single crystallinity, and specific exposed facets. (C) 2015 Elsevier B.V. All rights reserved.