Light-induced CO2 binding and reduction in a cerium MOF

What the study found: A cerium-based metal-organic framework, Ce-UiO-66-NH2, showed light-induced reversible binding of carbon dioxide and photoreduced it to carbon monoxide in water without sacrificial agents. The study reports 100% selectivity for carbon monoxide and a production rate of 126 μmol·g−1·h−1.
Why the authors say this matters: The authors conclude that this work will promote the design of photocatalysts capable of synthesizing fuels from carbon dioxide.
What the researchers tested: The researchers studied a cerium-based metal-organic framework with an amino-functionalized linker, comparing it with a non-amine analogue, Ce-UiO-66. They used in situ infrared spectroscopy, X-ray absorption, electron paramagnetic resonance, and transient absorption spectroscopy to examine what happens after photoexcitation.
What worked and what didn't: Photoexcitation induced ligand-to-metal charge transfer, which generated transient open Ce(III) sites. These sites bound CO2 in a μ-(η1-O)(η1-C) binding mode, and this reversible binding was linked to activation of CO2 for photoreduction to CO. The amino-functionalized material outperformed the non-amine analogue and benchmark catalysts reported to date, according to the abstract.
What to keep in mind: The abstract does not describe detailed limitations, and the summary is limited to the results and comparisons stated there.

Key points

• Ce-UiO-66-NH2 reversibly bound CO2 under light and reduced it to CO in water.
• The reported CO production rate was 126 μmol·g−1·h−1 with 100% selectivity.
• Photoexcitation created transient open Ce(III) sites through ligand-to-metal charge transfer.
• Those Ce(III) sites bound CO2 in a μ-(η1-O)(η1-C) mode.
• The amino-functionalized MOF outperformed Ce-UiO-66 and benchmark catalysts, according to the abstract.