Graphite-conjugated phthalocyanines through dioxin linkages: a molecularly programmable platform for heterogeneous CO2 electrocatalysis.

Combining the structural programmability of molecular catalysts with the robustness and direct electrode coupling of heterogeneous systems has long been pursued in electrocatalysis. Herein, we report a 1,4-dioxin conjugation strategy that covalently anchors metal phthalocyanines onto graphitic electrodes while simultaneously enabling programmable peripheral functionalization, thereby achieving molecular-level tunability within a heterogeneous platform. Perfluorinated Ni-phthalocyanine was grafted onto graphitic electrodes via cyclization between edge catechols and fluoro-groups, forming graphite-conjugated Ni-phthalocyanine (GC-NiPc). Using the same chemistry, substituted catechols bearing electron-donating/withdrawing groups (methyl, hydrogen, aldehyde, carboxyl, nitro, tetrachloro, and pyridyl) were incorporated onto the phthalocyanine periphery of GC-NiPc to tune the electronic structure of the phthalocyanine ring, resulting in an approximately 100 mV shift in redox potential that correlates linearly with Hammett constants of the substituents. This electronic modulation translated directly into altered CO2RR activity, with pyridine-modified GC-NiPc-Py achieving a high CO turnover frequency (1841 h-1) and above 99% faradaic efficiency over a wide potential window. In situ ATR-IR spectroscopy and DFT calculations further identified *COOH formation as the rate-determining step, with electron-withdrawing groups lowering the associated activation barrier. Compared with physisorbed analogues, the covalent conjugation strategy improves catalyst utilization and long-term stability, while programmable substituent engineering further enables systematic optimization of catalytic performance.