Metal-free graphdiyne doped with sp-hybridized boron and nitrogen atoms at acetylenic sites for high-efficiency electroreduction of CO2 to CH4 and C2H4

Abstract

Carbon dioxide electrochemical reduction (CO₂ER) to useful fuels and chemicals under ambient conditions provides an intriguing picture for resolving energy security and environmental issues, which mainly relies on metal-based electrocatalysts, but the emerging doped carbon-based materials hold great promise as metal-free alternatives. Here, by means of density functional theory (DFT) computations, the potential of the experimentally available doped graphdiyne (GDY) with boron (B) and nitrogen (N) atoms as the metal-free CO₂ER electrocatalyst was systematically explored. Our results revealed that these doped GDYs exhibit extremely high stability due to their high cohesive energies. Interestingly, the GDYs doped with sp-hybridized B and N at their acetylenic sites exhibit quite high-electrocatalytic activity for the conversion of CO₂ to CH₄ and (especially) C₂H₄ with a low limiting potential of about −0.60 V, which is attributed to their high electrical conductivity, preferable catalytic sites (sp-hybridized dopant), and low free energy for CO₂ activation. Thus, by carefully tailoring the dopant sites of B and N atoms, the doped GDY can be utilized as the metal-free CO₂ER catalyst with high-efficiency for the production of C1 and C2 species, which provides a new avenue to advance sustainable CO₂ conversion.