Editing Metal-free reduction of CO2 to formate using a photochemical organohydride-catalyst recycling strategy

{{DOI|doi=10.1038/s41557-023-01157-6}}
[[Category:Photocatalytic CO2 conversion to CH4]][[Category:Publication]]
{{BaseTemplate}}
===Abstract===
====Summary====
A photochemical reduction of CO<sub>2</sub> to formic acid was shown using {{#moleculelink:|link=RDSICPYJALLFAN-UHFFFAOYSA-M|image=false|width=300|height=200}} as catalyst in combination with the organic carbazole-based photosensitizer {{#moleculelink:|link=SEAGXMGVRJVEBS-UHFFFAOYSA-N|image=false|width=300|height=200}}. Turnover numbers (TONs) of 6080 for the catalyst and 8820 for the photosensitizer and an exclusive selectivity for formic acid were reached in MeCN/H<sub>2</sub>O. The experiments were conducted under visible-light irradiation (λ = 400 nm) using ascorbic acid as sacrificial electron donor (see section SEDs below) and potassium carbonate as a base.
====Advances and special progress====
A transition-metal free process for the efficient photocatalytic reduction of CO<sub>2</sub> to formic acid was described. The use of an organohydride catalyst allowed for a high selectivity for formate without noteworthy formation of H<sub>2</sub> or CO.

====Additional remarks====
Derivatives in which the carbazole and benzimidazolium moieties were covalently connected were tested as a combined catalyst/photosensitizer, but showed a lower activity in catalyzing CO<sub>2</sub> reduction.

===Content of the published article in detail===
The article contains results for the reduction of CO<sub>2</sub> to HCOO<sup>-</sup> under visible-light catalysis using {{#moleculelink:|link=RDSICPYJALLFAN-UHFFFAOYSA-M|image=false|width=300|height=200}} as a catalyst. The catalytic system performs best (referring to the TON of formic acid production) in MeCN/H<sub>2</sub>O with photosensitizer {{#moleculelink:|link=SEAGXMGVRJVEBS-UHFFFAOYSA-N|image=false|width=300|height=200}}.
====Catalyst====
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  -INDIGO-05152410312D

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M  V30 END BOND
M  V30 END CTAB
M  END
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====Photosensitizer====
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  -INDIGO-05152410182D

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M  V30 END BOND
M  V30 END CTAB
M  END
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  -INDIGO-05152410542D

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  -INDIGO-05152410562D

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M  V30 END CTAB
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====Investigation====
====Sacrificial electron donor====
In this study, the experiments were done with the sacrificial electron donor ascorbic acid {{#moleculelink:|link=PPASLZSBLFJQEF-UHFFFAOYSA-M|image=false|width=300|height=200}}. The use of BIH was tested, but found to yield worse results.
====Additives====
In this study, potassium carbonate was added as a base. Control experiments under argon and with other bases were performed.