Graphdiyene enables ultrafine Cu nanoparticles to selectively reduce CO_(2) to C_(2+)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 CO_(2) to multicarbon(O2+)products,owing to the overly strong binding of intermediates on small-sized(<15 nm)Cu nanoparticles(NPs).Herein,by incorporating pyreny-graphdiyne(Pyr-GDY),we successfully endowed ultrafine(〜2 nm)Cu NPs with a significantly elevated selectivity for CO_(2)-to-C_(2+)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,C_(2+)FE,〜18%),graphene oxide-supported Cu NPs(GO-Cu,C_(2+)FE,〜8%),and other reported ultrafine Cu NPs.Our results demonstrate the critical influence of graphdiyne on the selectivity of Cu-catalyzed CO_(2) electroreduction,and showcase the prospect for ultrafine Cu NPs catalysts to convert CO_(2) into value-added C_(2+)products.

Enhancing the photoelectrocatalytic performance of metal-free graphdiyne-based catalyst

As a new member of the carbon family,graphdiyne is an intrinsic semiconductor featuring a natural bandgap,which endues it potential for direct application in photoelectric devices.However,without cooperating with other active materials,conventional hexacetylene-benzene graphdiyne(HEB-GDY)shows poor performances in photocatalysis and photoelectric devices due to its non-ideal visible light absorption,low separation efficiency of the photogenerated carriers and insufficient sites for hydrogen production.Herein,we report a molecular engineering strategy for the regulation of GDY-based carbon materials,by incorporating a strong pyrene absorption group into the matrix of graphdiyne,to obtain pyrenyl graphdiyne(Pyr-GDY)nanofibers through a modified Glaser-Hay coupling reaction of 1,3,6,8-tetraethynylpyrene(TEP)monomers.For comparison,phenyl graphdiyne(Phe-GDY)nanosheets were also constructed using 1,3,4,6-tetraethynylbenzene(TEB)as a monomer.Compared with Phe-GDY,Pyr-GDY exhibits a wider visible light absorption band,promoted efficiency of the charge separation/transport and more sufficient active sites for water reduction.As a result,Pyr-GDY alone displays superior photoelectrocatalytic performance for water splitting,giving a cathode photocurrent density of^138μA cm-2 at a potential of-0.1 Vversus normal hydrogen electrode(NHE)in neutral aqueous solution,which is almost ten and twelve times as high as those of Phe-GDY(14μA cm-2)and HEB-GDY(12μA cm-2),respectively.Such a performance is also superior to those of most reported carbonbased metal-free photocathode.The results of theoretical calculations reveal that the carbon atoms in the acetylene bonds are the active sites for proton reduction.This work offers a new strategy for the construction of graphdiyne-based metal-free photoelectrocatalysts with enhanced photoelectrocatalytic performance.