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. 2025 Mar 19;147(11):9056-9061.
doi: 10.1021/jacs.4c18450. Epub 2025 Mar 7.

Cobalt-Embedded Metal-Covalent Organic Frameworks for CO2 Photoreduction

Wanpeng Lu  1 , Claudia E Tait  2 , Gokay Avci  3 , Xian'e Li  1   4 , Agamemnon E Crumpton  1 , Paul Shao  5 , Catherine M Aitchison  4 , Fabien Ceugniet  1 , Yuyun Yao  1 , Mark D Frogley  6 , Donato Decarolis  6 , Nan Yao  5 , Kim E Jelfs  3 , Iain McCulloch  1   7
Affiliations

Cobalt-Embedded Metal-Covalent Organic Frameworks for CO2 Photoreduction

Wanpeng Lu et al. J Am Chem Soc. .

Abstract

With the pressing urgency to reduce carbon footprint, photocatalytic carbon dioxide reduction has attracted growing attention as a sustainable mitigating option. Considering the important role of catalytic active sites (CASs) in the catalytic processes, control and design of the density and environment of CASs could enhance the catalyst performance. Herein, we report a novel metal-covalent organic framework (MCOF), MCOF-Co-315, featuring earth-abundant Co cocatalysts and conjugation through a covalently bonded backbone. MCOF-Co-315 showed a CO production rate of 1616 μmol g-1 h-1 utilizing Ru(bpy)3Cl2 as photosensitizer and triethanolamine (TEOA) as sacrificial electron donor with a 1.5 AM filter, vis mirror module (390-740 nm), and irradiation intensity adjusted to 1 sun and an especially outstanding apparent quantum yield (AQY) of 9.13% at 450 nm. The photocatalytic reaction was studied with electron paramagnetic resonance (EPR) spectroscopy, X-ray absorption near-edge structure (XANES), and in situ synchrotron Fourier Transform Infrared (FT-IR) spectroscopy, and an underlying mechanism is proposed.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
(a) Proposed linkage of MCOF-Co-315, viewed from the c axis (Co, orange; N, blue; C, gray; H omitted for clarity). (b) Diffraction pattern obtained from experimental PXRD and simulation. (c) Cryo-TEM of MCO-Co-315 at 20 nm resolution.
Figure 2
Figure 2
(a) Isothermal N2 adsorption–desorption of MCOF-Co-315 at 77 K. (b) Pore size distribution obtained from NLDFT. (c) XPS spectrum for illustrating Co oxidation state in MCOF-Co-315. (d) PESA measurement of drop-cast MCOF-Co-315. (e) UV–vis spectrum of the MCOF-Co-315 suspension in acetonitrile. (f) Calculated FMO energy level.
Figure 3
Figure 3
(a) CO production yield over MCOF-Co-315 in 8 h. (b) GCMS of isotope labeling experiment using 13CO2 as carbon source. (c) Cycle experiment based on the production yield in 8 h using MCOF-Co-315 as photocatalyst. (d) PXRD of MCOF-Co-315 before and after 5 cycles of photocatalysis. (e) AQY comparison of selected COF materials for CO2 photoreduction to CO in literature, more details in Table S2.
Figure 4
Figure 4
(a, b) In situ X-band EPR measurements performed as a function of time during photocatalysis with DMPO as a spin trap compared to simulations of DMPO adduct spectra. (c) EPR spectra of MCOF-Co-315 with Ru(bpy)3Cl2 before, during, and after illumination at 10 K.
Figure 5
Figure 5
(a) In situ synchrotron FT-IR spectroscopy of MCOF-Co-315 with incremental CO2 concentration in gas stream. (b) Normalized Co K-edge XANES spectra of MCOF-Co-315, MCOF-Co-315_post reaction, and reference samples (CoO and Co3O4). (c) Proposed reaction mechanism.
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