Merging an organic TADF photosensitizer and a simple terpyridine–Fe(iii) complex for photocatalytic CO2 reduction

Abstract

Summary

The photochemical reduction of CO₂ to CO was shown using the iron complex Fe(tpy-tol)Cl3 in combination with the organic photosensitizer 4CzIPN. Turnover numbers (TONs) of up to 2250 and a selectivity of 99.3% for CO were reached in DMF/H₂O. The experiments were conducted under visible-light irradiation (λ > 420 nm) with TEA (see section SEDs below) as sacrificial electron donor.

Advances and special progress

The presented study contains the first example for the use of an organic thermally activated delayed fluorescence (TADF) compound as a photosensitizer in CO₂ reduction.

Content of the published article in detail

The article contains results of a study for the reduction of CO₂ to CO using an iron complex and an organic TADF photosensitizer. The catalytic system performs best (referring to the TON of CO production) in DMF.

Catalyst

Fe(tpy-tol)Cl3

Photosensitizer

4CzIPN

Investigation

	cat	cat conc [µM]	PS	PS conc [mM]	e-D	e-D conc [M]	solvent A	.	.	.	λexc [nm]	.	TON CO	.
1.	Fe(tpy-tol)Cl3	0.01	4CzIPN	0.05	TEA	0.28	DMF				420-650		2250
2.	Fe(tpy-tol)Cl3	0.01	4CzIPN	0.01	TEA	0.28	DMF				420-650		133
3.	Fe(tpy-tol)Cl3	0.01	4CzIPN	0.05	TEA	0.28	DMF				420-650		244
4.	Fe(tpy-tol)Cl3	0.01	4CzIPN	0.1	TEA	0.28	DMF				420-650		246
5.	Fe(tpy-tol)Cl3	0.01	FeCl3	0.05	TEA	0.28	DMF				420-650		6
6.	Ru(bpy)3	0.01	4CzIPN	0.05	TEA	0.28	DMF				420-650		17
7.	Molecule:100955	0.01	4CzIPN	0.05	TEA	0.28	DMF				420-650		0
8.	Eosin Y	0.01	4CzIPN	0.05	TEA	0.28	DMF				420-650		0

Investigation-Name: photocatalytic reduction of CO2 to COExport

Sacrificial electron donor

In this study, the experiments were done with the sacrificial electron donor TEA (TEA).

Additives

In this study, no additives were tested. Control experiments with other photosensitizers (Ru(bpy)₃, Fluorescein and Eosin Y) and catalysts (FeCl3) were conducted.