Graphdiyene enables ultrafine Cu nanoparticles to selectively reduce CO₂ to C₂₊ products

Reducing the size of heterogeneous nanocatalysts is generally conducive to improving their atomic utilization and activities in various catalytic reactions. However, this strategy has proven less effective for Cu-based electrocatalysts for the reduction of CO₂ to multicarbon (C₂₊) products, owing to the overly strong binding of intermediates on small-sized (< 15 nm) Cu nanoparticles (NPs). Herein, by incorporating pyrenyl-graphdiyne (Pyr-GDY), we successfully endowed ultrafine (~ 2 nm) Cu NPs with a significantly elevated selectivity for CO₂-to-C₂₊ conversion. The Pyr-GDY can not only help to relax the overly strong binding between adsorbed H^* and CO^* intermediates on Cu NPs by tailoring the d-band center of the catalyst, but also stabilize the ultrafine Cu NPs through the high affinity between alkyne moieties and Cu NPs. The resulting Pyr-GDY-Cu composite catalyst gave a Faradic efficiency (FE) for C₂₊ products up to 74%, significantly higher than those of support-free Cu NPs (C₂₊ FE, ~ 2%), carbon nanotube-supported Cu NPs (CNT-Cu, C₂₊ FE, ~ 18%), graphene oxide-supported Cu NPs (GO-Cu, C₂₊ FE, ~ 8%), and other reported ultrafine Cu NPs. Our results demonstrate the critical influence of graphdiyne on the selectivity of Cu-catalyzed CO₂ electroreduction, and showcase the prospect for ultrafine Cu NPs catalysts to convert CO₂ into value-added C₂₊ products.