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

Abstract

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.