Pyridyl-containing graphdiyne stabilizes sub-2 nm ultrasmall copper nanoclusters for the electrochemical reduction of CO2

Developing novel carbonaceous materials with definite chemical structures is conducive to understanding structure-property relationships and expanding their applications in supported metal catalysts. Herein, a brand-new pyridine-substituted graphdiyne (Py-GDY) is synthesized through the cross-coupling of 1,3,5-triethynyl-2,4,6-tris(4-pyridyl)benzene, and further applied as a promising carrier in electrocatalysis. Thanks to the precisely introduced pyridyl groups, strong metal-support interaction between the confined Cu species and Py-GDY is desirably obtained, resulting in uniformly dispersed Cu sub-nanoclusters (< 2 nm) (Py-GDY-Cu). Conversely, the Cu size increased dramatically when the pyridyl group of Py-GDY was replaced by the phenyl group (Ph-GDY-Cu). In a proof-of-concept demonstration of the electrochemical CO2 reduction reaction, Py-GDY-Cu is found to produce CH4 preferentially to Ph-GDY-Cu, owing to the favorable sub-nanocluster size. As a result, an optimum CH4 faradaic efficiency of 58% is achieved on Py-GDY-Cu, which shows a 1.6-fold enhancement compared with that of Ph-GDY-Cu. This work broadens the scope of carbonaceous materials for rational metal species immobilization toward efficient catalysis.