Abstract
The reduction of carbon dioxide (CO₂) into valuable products will contribute to sustainable carbon use. Here we report the photocatalytic reduction of CO₂ to carbon monoxide, formate, and oxalate ions using a redox-active phenazine-based 2D covalent organic framework (Phen-COF) and its phenazine monomer. Under similar irradiation conditions, Phen-COF produced 2.9 times more CO, 11 times more formate, and 13 times more oxalate compared to equimolar amounts of the monomeric phenazine, demonstrating that the COF architecture enhances catalytic performance (TOFCOF: 10−7 s−1 CO, 10−8 s−1 formate, and 10−11 s−1 oxalate). Structural analysis, including X-ray diffraction and N₂ porosimetry, confirmed the COF's long-range order and porosity. Mechanistic studies suggest a sequential formate-to-oxalate pathway, with CO and formate acting as intermediates. These results demonstrate the potential of the COF architecture to improve the performance of metal-free, redox-active aromatic systems such as phenazines to facilitate efficient and selective CO₂ conversion under mild conditions.
| Original language | English (US) |
|---|---|
| Article number | e202502799 |
| Journal | Angewandte Chemie - International Edition |
| Volume | 64 |
| Issue number | 21 |
| DOIs | |
| State | Published - May 19 2025 |
Funding
This research was sponsored by the Army Research Office under Grant Number W911NF-23-1-0306. This work was also partially funded by the Trienens Institute for Sustainability and Energy at Northwestern University. Z.H. (DGE-1842165) was supported by the National Science Foundation Graduate Research Fellowship. Furthermore, the REACT Facility of the Northwestern University Center for Catalysis and Surface Science is supported by a grant from the DOE (DE-SC0001329). We are thankful to Dr. Vinita Dubey for providing the reactor design. Ion chromatography was performed at the Northwestern University Quantitative Bio-element Imaging Center with Rebecca A. Sponenburg, Msc. This work made use of the IMSERC (Crystallography, MS, and NMR facilities) at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), and Northwestern University. This work also made use of the EPIC, Keck-II, and NUANCE facilities at Northwestern University, which has received support from the SHyNE Resource (NSF ECCS-2025633), the State of Illinois, the International Institute for Nanotechnology (IIN), the Keck Foundation, and Northwestern's MRSEC program (NSF DMR-1720139) at the Materials Research Center. This research was sponsored by the Army Research Office under Grant Number W911NF\u201023\u20101\u20100306. This work was also partially funded by the Trienens Institute for Sustainability and Energy at Northwestern University. Z.H. (DGE\u20101842165) was supported by the National Science Foundation Graduate Research Fellowship. Furthermore, the REACT Facility of the Northwestern University Center for Catalysis and Surface Science is supported by a grant from the DOE (DE\u2010SC0001329). We are thankful to Dr. Vinita Dubey for providing the reactor design. Ion chromatography was performed at the Northwestern University Quantitative Bio\u2010element Imaging Center with Rebecca A. Sponenburg, Msc. This work made use of the IMSERC (Crystallography, MS, and NMR facilities) at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS\u20102025633), and Northwestern University. This work also made use of the EPIC, Keck\u2010II, and NUANCE facilities at Northwestern University, which has received support from the SHyNE Resource (NSF ECCS\u20102025633), the State of Illinois, the International Institute for Nanotechnology (IIN), the Keck Foundation, and Northwestern's MRSEC program (NSF DMR\u20101720139) at the Materials Research Center.
Keywords
- 2D polymers
- Carbon dioxide
- Covalent organic frameworks
- Organic semiconductors
- Photocatalysis
ASJC Scopus subject areas
- Catalysis
- General Chemistry
