Boosting Electron‐Hole Charge Separation in CO ₂ Photoreduction through Fluoroporphyrin‐Linked Nickel(II)‐Acetylide Frameworks

ABSTRACT Metal‐acetylide frameworks (MAFs) have emerged as efficient catalysts due to their unique d ‐ π orbital hybridization between transition metal ions and sp ‐hybridized carbons in multi‐acetylenic ligands, forming robust metal‐bis(acetylide) moieties. Herein, we report the synthesis of a novel nickel(II)‐acetylide framework (H ₂ TFPP‐Ni‐AF) featuring well‐defined ─C≡C─Ni(PBu ₃ ) ₂ ─C≡C─ (where Bu = ─CH ₂ CH ₂ CH ₂ CH ₃ ) catalytic sites, which demonstrates remarkable photocatalytic CO ₂ ‐to‐CO conversion rate. The catalyst achieves a CO yield of 52.64 mmol g ⁻¹ , an average production rate of 13.16 mmol h ⁻¹ g ⁻¹ , and 97.9% selectivity over a 4‐h reaction, substantially outperforming its metal‐free analogue (H ₂ TFPP‐GDY). Mechanistic insights from the combined experimental and theoretical studies reveal that the enhanced performance stems from the synergistic interplay between Ni ^II ‐bis(acetylide) moieties, which facilitate CO ₂ adsorption and activation, and fluoroporphyrin units, which enhance light‐harvesting and charge‐transport capabilities, leading to bandgap narrowing, improved electron‐hole charge separation, and reduced energy barrier for *COOH intermediate formation. Additionally, the electron‐deficient fluoroporphyrin acts as an electron acceptor, extracting photogenerated electrons from the Ni(PBu ₃ ) ₂ moieties and further promoting charge separation during the photocatalytic CO ₂ reduction reaction (CO ₂ RR). This work provides a rational design strategy for optimizing MAF‐based photocatalysts toward solar‐driven CO ₂ conversion.