Self-integrated β-Bi2O3/Bi2O2.33@Bi2O2CO3 ternary composites: Formation mechanism and visible light photocatalytic activity

Bi2O2CO3 with a narrow band gap (Eg similar to 2.93 eV) was self -assembled by Bi2O2CO3 nanosheets via a hydrothermal method, and the beta-Bi2O3/Bi2O2.33@Bi2O2CO3 composites were further fabricated using Bi2O2CO3 as template by slow thermal decomposition for 4h, described as: Bi2O2CO3 -> beta-Bi2O3/Bi2O2.33@Bi2O2CO3 (300 degrees C) beta-Bi2O3/Bi2O2.33 (320 degrees C) >beta-Bi2O3(350 degrees C). Deep investigation towards the generation and existence of beta-Bi2O3 and Bi2O2.33 on the surfaces and interfaces of Bi2O2CO3 were also carefully conducted by XRD, HRTEM and XPS analysis. In comparison with pure Bi2O2CO3, beta-Bi2O3/Bi2O2.33@Bi2O2CO3 displayed superior photocatalytic degradation efficiency and stability to cationic dyes under visible-light irradiation. Especially, the as-prepared BOC-300 degrees C with relatively high specific surface area (12.11 m(2) g(-1)) could entirely remove Rh-B and MB in 45 min and 60 min, which were approximately 4.7 and 6.6 times as high as that of pure Bi2O2CO3, respectively. Further study demonstrated that the enhanced photocatalytic degradation efficiency of beta-Bi2O3/beta i(2)O(2.33)@Bi2O2CO3 is surely owing to the well matched band gap and p-n heterojunction, which made it possible for much faster charge transfer rather than electron-hole pairs recombination process. (C) 2017 Elsevier B.V. All rights reserved.