Beyond Second Coordination Shell: Long‐Range π‐electrons delocalization Engineering in Single‐Atom Catalysts for CO2 Electroreduction

While long‐range charge delocalization beyond the second coordination shell critically influence the geometric and electronic properties of single‐atom active sites, their systematic modulation to enhance multi‐electron catalytic processes remains largely unexplored. Here, we demonstrate a site‐specific strategy to engineer the nickel tetraphenylporphyrin (NiTPP) precursors by selectively cleaving carbon‐carbon single bonds at the β‐carbon sites. This approach preserves the Ni‐centered first and second coordination shells while systematically removing peripheral π‐electron delocalization in extended coordination environments. The resultant Ni‐N4 catalyst exhibits a 29‐fold enhancement in CO faradaic efficiency at ‐1.4 V vs RHE compared to original counterparts. Notably, it maintains 98.3% CO selectivity at industrial‐grade current densities up to 500 mA cm‐2 in flow cell. Combined experimental and theoretical analyses reveal that the electron‐enriched Ni sites, arising from precisely regulated charge delocalization in higher coordination shells, facilitate stabilization of the critical *COOH intermediate. Our findings establish a paradigm for advanced catalyst design through deliberate engineering of higher coordination shells.