Visible-Light-Driven Photocatalytic CO2 Reduction by a Ni(II) Complex Bearing a Bioinspired Tetradentate Ligand for Selective CO Production

Abstract

Summary

A photochemical reduction of CO₂ to CO was shown using the nickel complex [Ni(bpet)(MeCN)2][ClO4]2 as catalyst in combination with the ruthenium-based photosensitizer Ru(bpy)3Cl2. Turnover numbers (TONs) over 700 and a selectivity of >99% for CO were reached in dimethylacetamide/water. The experiments were conducted under visible-light irradiation (λ = 450 nm) using BIH as sacrificial reductants (see section SEDs below).

Advances and special progress

A nickel catalyst inspired by the CODH enzyme (carbon monoxide dehydrogenase) was employed for the photocatalytic reduction of CO₂ with the back then highest reported TON values among nickel complexes in systems with [Ru(bpy)₃]²⁺.

Additional remarks

The binding of CO₂ to the nickel(0) species was identified as the potential rate-determining step of the reduction.

Content of the published article in detail

The article contains results for the reduction of CO₂ to CO under visible-light catalysis using a nickel complex as a catalyst. The catalytic system performs best (referring to the TON of CO production) in dimethylacetamide/water.

Catalyst

[Ni(bpet)(MeCN)2][ClO4]2

Photosensitizer

Ru(bpy)3Cl2

Investigation

	cat	cat conc [µM]	PS	PS conc [mM]	e-D	e-D conc [M]	solvent A	.	.	.	λexc [nm]	.	TON CO	.	TON H2	.	.
1.	[Ni(bpet)(MeCN)2][ClO4]2	0.03	Ru(bpy)3Cl2	0.5	BIH	0.1	DMA				450		713		6.9
2.	[Ni(bpet)(MeCN)2][ClO4]2	0.03	Ru(bpy)3Cl2	0.5	BIH	0.1	DMF				450		159		11
3.	[Ni(bpet)(MeCN)2][ClO4]2	0.03	Ru(bpy)3Cl2	0.5	BIH	0.1	DMA				450		67		3.4
4.	[Ni(bpet)(MeCN)2][ClO4]2	0.03	Ru(bpy)3Cl2	0.5	BIH	0.1	MeCN				450
5.	[Ni(bpet)(MeCN)2][ClO4]2	0.03	Ru(bpy)3Cl2	0.5	TEA	0.1	DMA				450
6.	[Ni(bpet)(MeCN)2][ClO4]2	0.03	Ru(bpy)3Cl2	0.5	TEOA	0.1	DMA				450		2.6		25.5

Investigation-Name: Table 1Export

Sacrificial electron donor

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

Additives

In this study, no additives were tested.