Continuous High‐Spin Orbital Coupling for Enhanced CO ₂ Photoreduction With H ₂ O in Covalent Organic Frameworks

Abstract

ABSTRACT Photocatalytic CO 2 reduction with H 2 O offers an ideal pathway for sustainable solar fuel production, yet its efficiency remains hindered by sluggish charge transfer and reaction kinetics. Here, we introduce continuous orbital‐coupling Ni–Nx covalent organic frameworks to overcome these constraints. Precise coordination tuning establishes strong π– d interactions for efficient charge separation and high‐spin triplet formation, while concurrently aligning intermediate p ‐orbitals with Ni d ‐orbitals to create a “π→d→p” coupling pathway. This continuous orbital network enables rapid high‐spin electron transfer from the framework to the catalytic center and onward to reaction intermediates, and lowers the rate‐determining energy barrier by ∼40%. Consequently, the optimized Ni–N6 catalyst achieves efficient photocatalytic CO 2 reduction with H 2 O with a CO and O 2 evolution rate of 57.17 and 27.07 µmol g −1 h −1 , respectively—a 7.5‐fold improvement over the weakly coupled analogue. This work establishes a generalizable principle for engineering coordination microenvironments toward high‐efficiency molecular photocatalysts.