Integrating polyarylether-COFs with TiO2 nanofibers for enhanced visible-light-driven CO2 reduction in artificial photosynthesis

Abstract

Artificial photosynthesis is considered a promising strategy to mitigate environmental issues and energy crises. Herein, one-dimensional oxide–semiconductor (TiO2-nanofiber, TNF) and polyarylether-based covalent organic framework (COF-318) were composed to form a visible-light responsive heterojunction (COF-318/TNF) for artificial photosynthesis by simultaneously triggering CO2 reduction and H2O oxidation. Without additional sacrificial agents, photosensitizers or cocatalysts, the optimal sample COF-318/TNF-15 exhibited CO2-to-CO conversion efficiency of 70.1 ± 0.7 µmol∙g−1∙h−1, 12.7 times higher than that of COF-318. The molar ratio of produced CO to O2 was about 2:1, suggesting H2O was the electron donor in the photocatalytic process. Photoelectrochemical measurements and time-resolved transient absorption spectra illustrated the high separation/transfer efficiency of photo-generated charges in COF-318/TNF-15, which was attributed to the construction of heterojunction and the specific one-dimensional property of TiO2 nanofibers. During the CO2 photoreduction, HCOO* was detected as the key intermediate for CO production according to the in-situ FT-IR analysis. This work provides a new route for the rational design of organic–inorganic heterogeneous photocatalysts for visible-light-driven CO2 reduction.