Linker engineering in metal-organic frameworks for dark photocatalysis

• Published in: Chemical science (Cambridge) Vol. 13; no. 22; pp. 6696 - 673
• Main Authors: Pan, Yating, Wang, Jingxue, Chen, Shengyi, Yang, Weijie, Ding, Chunmei, Waseem, Amir, Jiang, Hai-Long
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.06.2022; The Royal Society of Chemistry
• Subjects: Chemistry; Energy storage; Functional groups; Hydrogen production; Light sources; Metal-organic frameworks; Nitrogen dioxide; Photocatalysis; Photocatalysts; Photosynthesis; Titanium
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d1sc06785k

Dark reactions featuring continuous activity under light off conditions play a critical role in natural photosynthesis. However, most artificial photocatalysts are inactive upon the removal of the light source, and the artificial photocatalysts with dark photocatalysis abilities have been rarely explored. Herein, we report a Ti-based metal-organic framework (MOF), MIL-125, exhibiting the capability of dark photocatalytic hydrogen production. Remarkably, the introduction of different functional groups onto the linkers enables distinctly different activities of the resulting MOFs (MIL-125-X, X = NH 2 , NO 2 , Br). Dynamic and thermodynamic investigations indicate that the production and lifetime of the Ti 3+ intermediate are the key factors, due to the electron-donating/-withdrawing effect of the functional groups. As far as we know, this is the first report on dark photocatalysis over MOFs, providing new insights into the storage of irradiation energy and demonstrating their great potential in dark photocatalysis due to the great MOF diversity. A Ti-based MOF with long-lived Ti 3+ can achieve dark photocatalysis. The different groups on the organic linker modulate electron storage ability and the lifetime of Ti 3+ , significantly regulating dark photocatalytic activity in H 2 production.