Issue 12, 2024

Local protons enhance photocatalytic CO2 reduction by porphyrinic zirconium-organic frameworks

Abstract

The immobilization of molecular catalysts based on porphyrin fragments within metal–organic frameworks (MOFs) offers a promising approach for achieving sustainable and stable photocatalytic activity. In this study, we presented the synthesis of a phenolic hydroxy-modified iron-porphyrinic zirconium-based MOF, Zr6O4(OH)4(FeTCBPP-OH)3, named MOF-OH (FeTCBPP-OH = iron 5,10,15,20-tetrakis[4-(4′-carboxyphenyl)-2,6-dihydroxylphenyl]porphyrin), through post-synthetic modification of a precursor MOF called MOF-OCH3 (Zr6O4(OH)4(FeTCBPP-OCH3)3, FeTCBPP-OCH3 = iron 5,10,15,20-tetrakis[4-(4′-carboxyphenyl)-2,6-dimethoxyphenyl]porphyrin). Initially, we attempted the direct assembly of Zr4+ centers and FeTCBPP-OH ligands; however, this approach was unsuccessful in obtaining MOF-OH. This perhaps resulted from the high number of hydroxyl groups on the polyphenolic porphyrinic fragments, which exhibited a stronger binding affinity towards zirconium centers. Consequently, we achieved MOF-OH by selectively modifying the partial methoxy positions of the FeTCBPP-OCH3 fragments in MOF-OCH3 through demethylation. To evaluate the photocatalytic performance of MOF-OH, we conducted CO2 reduction experiments without any additional photosensitizer. Remarkably, after 72 hours, the yield of CO reached a high value of 26.8 mmol g−1. Notably, the CO production of MOF-OH was significantly higher than that of MOF-OCH3, possibly due to the presence of phenolic hydroxyl substituents, which led to higher local proton concentrations. Furthermore, MOF-OH exhibited excellent stability, as demonstrated by the consistent CO production observed during four consecutive runs of CO2 reduction. To gain insights into the photocatalytic CO2 reduction process, we conducted a comprehensive series of characterizations and density functional theory calculations, which provided a deeper understanding of the mechanism involved.

Graphical abstract: Local protons enhance photocatalytic CO2 reduction by porphyrinic zirconium-organic frameworks

Supplementary files

Article information

Article type
Research Article
Submitted
08 mar 2024
Accepted
16 apr 2024
First published
18 apr 2024

Mater. Chem. Front., 2024,8, 2439-2446

Local protons enhance photocatalytic CO2 reduction by porphyrinic zirconium-organic frameworks

X. Zhao, C. Zhu, J. Qin, H. Rao, D. Du, M. Zhang, P. She, L. Li and Z. Su, Mater. Chem. Front., 2024, 8, 2439 DOI: 10.1039/D4QM00187G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements