Visible-light photocatalytic conversion of carbon dioxide by Ni(II) complexes with N4S2 coordination: Highly efficient and selective production of formate

Sung Eun Lee, Azam Nasirian, Ye Eun Kim, Pegah Tavakoli Fard, Youngmee Kim, Byeongmoon Jeong, Sung Jin Kim, Jin Ook Baeg, Jinheung Kim

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

The efficient and selective light-driven conversion of carbon dioxide to formate is a scientific challenge for green chemistry and energy science, especially utilizing visible-light energy and earth-abundant catalytic materials. In this report, two mononuclear Ni(II) complexes of pyridylbenzimidazole (pbi) and pyridylbenzothiazole (pbt), such as Ni(pbt)(pyS)2 (1) and Ni(pbi)(pyS)2 (2) (pyS = pyridine-2-thiolate), were prepared and their reactivities studied. The two Ni complexes were examined for CO2 conversion using eosin Y as a photosensitizer upon visible-light irradiation in a H2O/ethanol solvent. The photoreaction of CO2 catalyzed by complexes 1 and 2 selectively affords formate with a high efficiency (14 000 turnover number) and a high catalytic selectivity of 99%. Undesirable proton reduction pathways were completely suppressed in the photocatalytic reactions with these sulfur-rich Ni catalysts under CO2. Hydrogen photoproduction was also studied under argon. Their kinetic isotope effects and influence of solution pH for formate and H2 production in the photocatalytic reactions are described in relation to the reaction mechanisms. These bioinspired Ni(II) catalysts with N/S ligation in relation to [NiFe]-hydrogenases are the first examples of early transition metal complexes affording such high selectivity and efficiencies, providing a future path to design solar-to-fuel processes for artificial photosynthesis.

Original languageEnglish
Pages (from-to)19142-19149
Number of pages8
JournalJournal of the American Chemical Society
Volume142
Issue number45
DOIs
StatePublished - 11 Nov 2020

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