Highly dispersed nickel site catalysts for diluted CO₂ photoreduction to CO with nearly 100% selectivity

Photoconversion of CO₂ into value-added fuels has aroused widespread interest; however, this process is significantly limited by the inefficient thermodynamics and sluggish reaction dynamics in the diluted CO₂. To circumvent these obstacles, we design a bipyridine-based polyimide polymer for anchoring single Ni site for diluted CO₂ photoreduction. The desired Ni single atomic catalysts achieve high generation activity of ∼ 2262 μmol/h with apparent quantum efficiency (A.Q.E.) of 0.20% for CO₂-to-CO in 0.1 atm CO₂ pressure. No measurable H₂ is produced in the catalytic process, affording nearly 100% CO selectivity over water splitting. This superior activity and selectivity outperform most previous atomical catalysts. Mechanistic analyses elucidate that the highly dispersed Ni atoms act as active sites for effective CO₂ binding and activation, and stabilize the rate-determining step of intermediates for CO generation. This work discloses the relationship between catalytic properties and single atoms for efficient solar-driven diluted CO₂ reduction.