Electronic Structure Modulation via Curvature Engineering Enables C–C/C–N Coupling on Co–Graphdiyne for Selective CO2 Reduction

Abstract

Single-atom catalysts provide maximum atomic utilization for CO2 electroreduction (CO2RR), yet achieving high selectivity while suppressing the competing hydrogen evolution reaction (HER) remains challenging. Here, density functional theory calculations demonstrate that curvature engineering of Co–graphdiyne (Co–GDY) effectively modulates the electronic structure of the Co active site and enhances catalytic performance. It was observed that the planar Co–GDY configuration exhibits a limiting barrier of 0.45 eV for CO2-to-CH4 conversion but suffers from significant HER competition due to excessive negative charge accumulation on the carbon atoms surrounding the Co center. Introducing a tubular curvature redistributes the local charge density, weakens Coulombic repulsion, suppresses HER, and reduces the limiting barrier to 0.40 eV. Beyond C1 products, the modified structure stabilizes CH2O intermediates and enables efficient C–C coupling with a low kinetic barrier of 0.29 eV, requiring only 0.14 V for C2H4 formation. Strong CO adsorption and favourable N2 activation on modified structure further allow feasible C–N coupling toward CO(NH2)2 synthesis under low applied potential. These findings establish curvature modulation as an effective strategy for designing multifunctional electrocatalysts for sustainable carbon utilization.