Combination of covalent-organic framework and Bi2O2S by covalent bonds to form p-n heterojunction for enhanced photocatalytic CO2 conversion
Yue-Han Wu, Jisheng Liu, Jian Rong, Yuzhe Zhang, Qian Liang, Man Zhou, Zhongyu Li, Song Xu
Abstract
The objective of current photocatalysis research is to increase the separation efficiency of photogenerated carriers and convert CO 2 into useful resources for human beings. In the present study, TpPa-2-COF was successfully grown in situ on Bi 2 O 2 S nanosheets by hydrothermal and thermal solvent two-step experimental method, and a typical p-n heterojunction was constructed by covalent-bond between TpPa-2-COF and Bi 2 O 2 S, which significantly improved the photocatalytic activity of CO 2 . When Bi 2 O 2 S@TpPa-2-COF-15 heterojunction was illuminated with 300 W xenon lamp for 3 h, the CO yield reached 19.5 μmol·g −1 ·h −1 , while the CH 4 yield reached 6.2 μmol·g −1 ·h −1 . Compared with pure TpPa-2-COF and Bi 2 O 2 S, the photocatalytic activity of the Bi 2 O 2 S@TpPa-2-COF-15 increased 66.8 and 3.96 times, respectively. Meanwhile, the Bi 2 O 2 S@TpPa-2-COF-15 composite showed good stability under multiple cycles. Furthermore, the mechanism of Bi 2 O 2 S@TpPa-2-COF heterojunction enhanced photocatalytic reduction of CO 2 was also proposed. The experimental and characterization findings have shown that the transit of photo-generated electron-hole pairs via TpPa-2-COF to Bi 2 O 2 S may be greatly promoted to achieve the effect of electron hole separation under visible-light irradiation.