The direct usage of CO2 in the flue gas to produce fuels or chemicals is of great significance from energy-saving and low-cost perspectives, yet it is still underexplored. Herein, we report the photoreduction of CO2 from the simulated industrial exhaust by synergistic catalysis of TEOA and a metal-free composite (COF1-g-C3N4) fabricated via covalently grafting COF1 with g-C3N4. The hydrogen bond interaction between TEOA and hydrazine units on COF1 is detected in diluted CO2, which leads to significantly enhanced light absorption in the whole visible-light region. Also, the photo-induced electrons undergo fast transfer from COF1 to g-C3N4. This kind of dynamic interface with enhanced light absorption and electron transfer effects promotes the photosynthetic yield of syngas to 165.6 μmol·g-1·h-1 with the use of simulated exhaust gas as a raw material directly. The photosynthetic yield of syngas ranks among the highest of known metal-free catalysts in diluted CO2. This work provides a general rule for designing efficient catalysts via a controlled catalytic interface and new insights into the role of TEOA in photochemical CO2 reduction.
Keywords: CO2 photoreduction; covalent organic frameworks; flue gas; g-C3N4; synergistic catalysis.