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.