Light-Driven Reduction of CO2 to CO in Water with a Cobalt Molecular Catalyst and an Organic Sensitizer

Abstract

Summary

A photochemical reduction of CO2 to CO was shown using the cobalt complex [Co(qpy)(H2O)2][ClO4]2 (100788) as a catalyst in combination with the organic, water soluble triazatriangulenium photosensitizer (100797). Turnover numbers (TONs) up to 19000 and selectivity of 93% for CO were reached in acetonitrile with 20% of water. The experiments were conducted under visible-light irradiation (λ > 450 nm) using tertiary amines or BIH as sacrificial reductants (see section SEDs below).

Advances and special progress

The photoreduction of CO2 to CO could be shown in 100% water with a TON of 2600 and a selectivity of 94% without any noble metals or rare materials.

Content of the published article in detail

The article contains results for the reduction of CO2 to CO under visible-light catalysis using a cobalt complex as a catalyst. The catalytic system performs best (referring to the TON of CO production) in acetonitrile with 20% water using BIH and TEOA.

Catalyst

[Co(qpy)(H2O)2][ClO4]2 (100788) CoCl2 (100798)

Photosensitizer

(100797)

Investigations

		cat	cat conc [µM]	PS	PS conc [mM]	e-D	e-D conc [M]	solvent A	.	.	additives	λexc [nm]	TON CO	TON H2	TON HCOOH	.	.
(edit)	1.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1	MeCN				450	2332	106	1370
(edit)	2.			Molecule:100797	0.2	BIH	0.1	MeCN				450	0	0	0
(edit)	3.	[Co(qpy)(H2O)2][ClO4]2	0.002			BIH	0.1	MeCN				450	0	0	0
(edit)	4.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2			MeCN				450	950	86	316
(edit)	5.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1	MeCN				450	107	7	5
(edit)	6.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1	MeCN			Argon atmosphere	450	0	7	0
(edit)	7.	CoCl2	0.005	Molecule:100797	0.2	BIH	0.1	MeCN				450	0	159	0
(edit)	8.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1	MeCN			Hg (0.1 mL)	450	1880	255	1973

Investigation-Name: Visible-Light Driven CO2 Reduction with 1/TATA+/BIH + TEOA under Various Conditions

		cat	cat conc [µM]	PS	PS conc [mM]	e-D	e-D conc [M]	.	.	solvent A	.	.	additives	λexc [nm]	TON CO	TON H2	TON HCOOH	.	.
(edit)	1.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	2332	106	1370
(edit)	2.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	6228	304	2441
(edit)	3.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	14691	283	1097
(edit)	4.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	15822	220	1147
(edit)	5.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	18989	227	1215
(edit)	6.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN			Hg	450	19646	226	415
(edit)	7.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	183	9	419
(edit)	8.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	612	202	51
(edit)	9.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	515	253	46
(edit)	10.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	3171	498	179
(edit)	11.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN				450	6331	264	179
(edit)	12.	[Co(qpy)(H2O)2][ClO4]2	0.002	Molecule:100797	0.2	BIH	0.1			MeCN			Hg	450	6286	304	97

Investigation-Name: Photocatalytic CO2 Reduction by 1 (2 μM) in CO2-Saturated Aqueous CH3CN Solutions

Sacrificial electron donor

In this study, the experiments were done with the sacrificial reductants TEOA (100507), BIH (100508), and TEA (100505).

BIH (100508)