Dual electronic effects achieving a high-performance Ni(II) pincer catalyst for CO<sub>2</sub> photoreduction in a noble-metal-free system.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35998222.
- Also identified by DOI 10.1073/pnas.2119267119 and PMC identifier 9436338.
- Licence recorded as CC BY-NC-ND.
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Abstract
A carbazolide-<i>bis</i>(NHC) Ni<sup>II</sup> catalyst (1; NHC, <i>N</i>-heterocyclic carbene) for selective CO<sub>2</sub> photoreduction was designed herein by a one-stone-two-birds strategy. The extended π-conjugation and the strong σ/π electron-donation characteristics (two birds) of the carbazolide fragment (one stone) lead to significantly enhanced activity for photoreduction of CO<sub>2</sub> to CO. The turnover number (TON) and turnover frequency (TOF) of 1 were ninefold and eightfold higher than those of the reported pyridinol-<i>bis</i>(NHC) Ni<sup>II</sup> complex at the same catalyst concentration using an identical Ir photosensitizer, respectively, with a selectivity of ∼100%. More importantly, an organic dye was applied to displace the Ir photosensitizer to develop a noble-metal-free photocatalytic system, which maintained excellent performance and obtained an outstanding quantum yield of 11.2%. Detailed investigations combining experimental and computational studies revealed the catalytic mechanism, which highlights the potential of the one-stone-two-birds effect.