Visible-Light Photocatalytic Reduction of CO2 to Formic Acid with a Ru Catalyst Supported by N,N’- Bis(diphenylphosphino)-2,6-diaminopyridine Ligands

Abstract

Summary

A photochemical reduction of CO₂ to formic acid was shown using the ruthenium pincer complexes Ru(py)-(HNdpp)2(CO)2Cl and Ru(py)-(MeNdpp)2(CO)2Cl as catalyst in combination with the ruthenium-based photosensitizer [Ru(bpy)3][PF6]. Turnover numbers (TONs) of 380 for formic acid were reached in dimethylformamide with complex Ru(py)-(MeNdpp)2(CO)2Cl. The experiments were conducted under visible-light irradiation (λ = 405 nm) using TEOA as sacrificial reductants (see section SEDs below).

Advances and special progress

The authors report a novel molecular architecture for a ruthenium photocatalyst active in the reduction of CO₂ to formic acid, displaying competitive TONs and quantum yields up to 14%.

Content of the published article in detail

The article contains results for the reduction of CO₂ to formic acid under visible-light catalysis using ruthenium complexes as catalysts. The catalytic system performs best (referring to the TON of formic acid production) with complex Ru(py)-(MeNdpp)2(CO)2Cl in dimethylformamide.

Catalyst

100772 [Show R-Groups]

Photosensitizer

[Ru(bpy)3][PF6]

Investigation

	cat	cat conc [µM]	PS	PS conc [mM]	e-D	solvent A	.	λexc [nm]	.	TON H2	TON HCOOH	.
1.	Ru(py)-(MeNdpp)2(CO)2Cl	0.025	[Ru(bpy)3][PF6]	0.025	TEOA	DMF		405			380
2.	Ru(py)-(MeNdpp)2(CO)2Cl	0.05	[Ru(bpy)3][PF6]	0.05	TEOA	DMF		405			210
3.	Ru(py)-(MeNdpp)2(CO)2Cl	0.1	[Ru(bpy)3][PF6]	0.1	TEOA	DMF		405		57.5	363
4.	Ru(py)-(MeNdpp)2(CO)2Cl	0.5	[Ru(bpy)3][PF6]	1	TEOA	DMF		405		14	162
5.	Ru(py)-(MeNdpp)2(CO)2Cl	1	[Ru(bpy)3][PF6]	1	TEOA	DMF		405		13.3	90.5
6.	Ru(py)-(HNdpp)2(CO)2Cl	0.5	[Ru(bpy)3][PF6]	1	TEOA	DMF		405		14	70.5
7.	Ru(py)-(HNdpp)2(CO)2Cl	1	[Ru(bpy)3][PF6]	1	TEOA	DMF		405		12	44.5
8.	Ru(py)-(HNdpp)2(CO)2Cl	2	[Ru(bpy)3][PF6]	1	TEOA	DMF		405		9.3	41.5

Investigation-Name: Table 1Export

Sacrificial electron donor

In this study, the experiments were done with the sacrificial electron donors TEOA (100507).

Additives

In this study, no additives were tested.