Visible-Light Photocatalytic Conversion of Carbon Dioxide by Ni(II) Complexes with N4S2 Coordination: Highly Efficient and Selective Production of Formate

Abstract

Summary

A photochemical reduction of CO₂ to formate was shown using the nickel complexes Ni(pbi)(pyS)2 or Ni(pbt)(pyS)2 as catalysts in combination with the organic photosensitizer Eosin Y. Turnover numbers (TONs) of up to 14000 and a selectivity of >99% for formate were reached in ethanol/water. The experiments were conducted under visible-light irradiation (λ > 400 nm) using TEOA as sacrificial electron donor (see section SEDs below).

Advances and special progress

A set of bioinspired nickel complexes have been developed and shown to possess remarkably high efficiencies and selectivities as catalysts in CO₂ reduction, being the (at that time) best early transition metal complexes for photocatalytic CO₂ conversion.

Additional remarks

The nickel complexes were also active catalysts for hydrogen photoreduction under argon atmosphere.

Content of the published article in detail

The article contains results for the reduction of CO₂ to formate under visible-light catalysis using nickel complexes and an organic photosensitizer. The catalytic system performs best (referring to the TON of formate production) in ethanol/water with complex Ni(pbi)(pyS)2 as a catalyst.

Catalyst

Ni(pbi)(pyS)2 Ni(pbt)(pyS)2

Photosensitizer

Eosin Y

Investigation

	cat	cat conc [µM]	PS	PS conc [mM]	e-D	e-D conc [M]	solvent A	.	.	.	.	TON HCOOH	.	.	.
1.	Ni(pbi)(pyS)2	0.004	Eosin Y	2	TEOA	0.4	H2O					14000
2.	Ni(pbt)(pyS)2	0.004	Eosin Y	2	TEOA	0.4	H2O					13100

Experiment-Name: Table 1Export

Sacrificial Electron Donor

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

Additives

In this study, no additives were tested.