Switchable CO₂ Photoreduction Selectivity via Organic Bases in Dual-Component Earth-Abundant Metal Systems

Photocatalytic CO2 reduction is a promising strategy for carbon-neutral fuel production, especially if highly selective catalysts based on earth-abundant metals can be developed. In this work, we demonstrated that the addition of organic bases to a dual-component photocatalytic system can switch the selectivity toward formate and carbon monoxide (CO). The system in this study consists of a pyrene-modified iron porphyrin catalyst and an organic donor–acceptor cyanoarene photosensitizer. Under visible light irradiation without any bases, formate emerged as the predominant product, achieving a turnover number (TON) of 1694 and 71% selectivity. Upon introducing an organic base, the product distribution shifted toward CO. Notably, upon addition of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), the CO selectivity increased to 84%, with a TONCO of 1787. Mechanistic studies indicated that the organic base shifts the nucleophilic active species from a hydride ([FeIHL]2–) to a [Fe0L]2– that can directly attack CO2 thereby leading to different reaction pathways and tuning the product selectivity.