Red‐Light‐Driven CO₂Photoreduction into CH₄and CO Enabled by Narrow‐Gap Conjugated Microporous Polymers

Abstract

Herein, selective CO2 photoreduction into CH4 and CO with red light using conjugated microporous polymers (CMPs) at room temperature is reported. By incorporating electron‐rich pyrene and electron‐deficient fluorenone derivatives in the polymer networks to constructing intramolecular donor–acceptor system, the resulting three polymers show very broad light absorption covered from 350 to 1000 nm, with narrow gaps of 1.61–1.74 eV. In the presence of triethanolamine and 1‐benzyl‐1,4‐dihydronicotinamide as the sacrificial agents, P3 exhibits the best visible‐light reduction activity, with CH4 and CO evolution rates of 932.9 and 943.4 μmol h−1 g−1, respectively. Most significantly, under the irradiation of red light (>600 nm), high evolution rates of CH4 and CO for P3 are achieved at 293.7 and 282.6 μmol h−1 g−1, as well as nearly 100% reaction selectivity. The better performance of P3 than P1 and P2 can be ascribed to the high absorption toward CO2 and improved charge transfer under light irradiation. This work opens great opportunities for designing broadband‐responsive CMPs for solar‐driven photocatalytic conversion.

Extending the π-Conjugated System in Conjugated Microporous Polymers to Modulate Excitonic Effects for Metal-Free Selective CO2 Photoreduction to CH4

“…To our knowledge, rare examples have been conducted for photocatalytic CO 2 reduction without any metal involvement. For this reason, it is highly desirable to use organic π-conjugated polymers, especially CMPs, as photocatalysts for metal-free photocatalytic CO 2 -to-CH 4 conversion, but thus far, only a few studies have been conducted. ,− For instance, Maji and co-workers reported that the donor–acceptor-based redox-active CMP with electron delocalization channel as a metal-free photocatalyst exhibited an impressive activity of CO 2 reduction to produce CH 4 with high generation rate and selectivity. Undoubtedly, the research of metal-free photocatalytic CO 2 -to-CH 4 conversion is still in its infancy, and rational designing of abundant yet unique catalytic sites in CMPs to improve the selectivity control of CH 4 versus other C 1 products is largely underexplored.…”

Highly Selective Photosynthesis of Formic Acid by Unifying the Products of CO2 Reduction and Methanol Oxidation

“…were generally substituted for water as electron donors to rapidly annihilate photogenerated holes to facilitate the efficient utilization of photogenerated electrons in CO 2 reduction. [18][19][20][21][22][23][24] However, this strategy not only wastes the energy of photogenerated holes, but the employment of high-cost sacrificial agents also significantly reduces the economic efficiency of the system. [25] To get rid of this dilemma, coupling CO 2 photoreduction and organic synthesis, that is, harnessing photogenerated holes to trigger valuable organic reactions, offers a win-win strategy for ameliorating the economic efficiency of photocatalytic CO 2 reduction.…”

“…were generally substituted for water as electron donors to rapidly annihilate photogenerated holes to facilitate the efficient utilization of photogenerated electrons in CO 2 reduction. [ 18–24 ] However, this strategy not only wastes the energy of photogenerated holes, but the employment of high‐cost sacrificial agents also significantly reduces the economic efficiency of the system. [ 25 ]…”

Fabrication of novel fluorene incorporated conjugated microporous polymer nanotubes for visible-light CO2 reduction with water vapor

“…Fluorene is selected as a comonomer because of its inherent advantages of facile preparation and rigid planar structure for effective charge transport. 28,29 Under visible light (>420 nm) and in an atmosphere of water vapor, TEB-Flu with a surface area of 486 m 2 g −1 exhibited a CO generation rate of 40.4 μmol h −1 g −1 and ∼100% selectivity. By introducing 1,3,5-triphenylbenzene as a more extended core, the CO production rate of TPB-Flu could be greatly boosted to 83.1 μmol h −1 g −1 , due to the reduced optical gap, improved CO 2 adsorption and charge migration during the photocatalytic process.…”