A DFT study on the selectivity of CO2 reduction electrocatalyzed by heterofluorene bis-NHC Ni pincer complexes: Interplay of media and structure factor

In this communication, two heterofluorene bis-NHC-Ni pincer complexes with different coordinating atoms (B/N) were designed and studied as CO2 reduction electro-catalysts. The selectivity between CO and HCOO– is affected by the interplay of media and structure factors. [Display omitted] •Two heterofluorene-bis-NHC Ni pincer complexes were computationally investigated.•The selectivity is affected by the interplay of media and structure factors.•The trans effect is influenced by the electron-donation and the steric hindrance. To provide a comprehensive theoretical understanding of the selectivity between CO and HCOO– for electrocatalytic CO2 reduction, two heterofluorene bis-NHC-Ni pincer complexes (B-Ni, N-Ni) have been designed and computationally studied. The vital roles of the media and structure factors on the selectivity have been elucidated. For the media factor, high acidity favors CO formation while alkaline media favors the HCOO– generation. On the other hand, the structural factors tune the selectivity via the trans effect of the heterofluorene that is affected by the electron-donation and the steric hindrance. This work should be helpful for the development of efficient and selective photo-/ electro-catalysts for CO2 reduction.