Control of CO ₂ Electrocatalysis via Modularly Customizable Graphdiyne

On-demand customization of materials with tailored structures and properties is a long-standing goal in materials science. Yet conventional materials often exhibit complex configurations, hindering unified design principles and limiting performance optimization. Here, utilizing modular graphdiyne (GDY) as a configurable platform, we present a chemically guided molecular design framework to achieve atomic-level precision control over catalytic behaviors. By combining density functional theory (DFT) with experimental validation, we systematically introduced electron-donating and electron-withdrawing groups to construct 13 organic molecular units, yielding modularly customizable GDYs with predetermined structures, enabling us to disentangle the interplay between structure and catalytic function. We identified a volcano-shaped correlation, linking the oxidation state of the active alkyne carbons to CO₂ reduction (CO₂RR) activity. Furthermore, we established that this oxidation state is directly correlated with intrinsic electronic descriptors, including work function, VBM, and Fermi level (<i>E</i>_f)─constructing a predictive framework. In particular, by precisely tuning the oxidation state of <i>sp</i>-hybridized carbons, we showed that GDYs can rationally optimize intermediate binding energies and effectively resolve the conventional trade-off between the CO₂RR activity and HER suppression. This mechanistic approach enables systematic control of the CO/H₂ ratio from 1:10 to 13:1. Notably, the fluorinated GDY (3FGDY) achieves a remarkable 93% CO Faradaic efficiency with sustained stability over 90 h. These findings establish a direct atomic-level structure-performance relationship and provide a robust proof-of-concept for modular materials design, with promising implications for syngas production and sustainable energy conversion.