A Bio‐Inspired Bimetallic Fe−M Catalyst for Electro‐ and Photochemical CO2 Reduction

Abstract The conversion of CO 2 into fuels or commodity chemicals by electrochemical or photochemical reduction is a promising strategy to relieve the ongoing energy crisis and increasing environmental pollution. Inspired by naturally occurring bimetalloenzymes, we have designed hetero–bimetallic CO 2 reduction catalysts ( FeM ) that involve linking an iron tetraphenylporphyrin ( FeP ) with a tripyridylamine (TPA) moiety, which provides a distal chelating site for Cu 2+ or Zn 2+ . We found that the introduction of Cu 2+ or Zn 2+ to FeP greatly enhances its efficiency as a catalyst for the electrochemical reduction of CO 2 . To gain insights into the observed synergistic effect, we performed mechanistic studies together with density functional theory (DFT) calculations. Our results show that Cu 2+ or Zn 2+ activates CO 2 towards reduction due to its Lewis acidity; it also functions as an oxo acceptor from CO 2 . FeM also functions as an efficient catalyst for the visible‐light‐driven reduction of CO 2 using either [Ru(bpy) 3 ] Cl 2 or fac ‐Ir(ppy) 3 (where bpy=2,2’‐bipyridine, ppy=2‐phenylpyridine) as photosensitizer and 1,3‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐benzo[d] imidazole (BIH) as sacrificial reductant. Again, the catalytic efficiency is enhanced by the presence of Cu 2+ or Zn 2+ . Our results provide a general strategy for the design of a series of hetero‐bimetallic catalysts for the reduction of CO 2 .