Rapid Hole Generation via D–A Structure‐Dependent Built‐In Electric Field of Deacetylated Chitin‐PDI for Efficient Photocatalytic Oxidation

Abstract Breaking the trade‐off between broad spectrum response and efficient charge separation is a major challenge in the photocatalysis. Unlike the conventional practice of suppressing charge separation when shrinking the bandgap, a series of deacetylated chitin‐perylene diimide (DC‐PDI) donor–acceptor (D–A) photocatalysts is proposed with tunable charge distribution by modulating the C─N covalent bond content, expanding the spectral absorption range as the expanded D–A. The enlarged D–A structure achieves efficient photogenerated electron–hole separation by increasing the charge of the positive and negative charge centers, inducing larger dipole moments, generating 4.7 times higher built‐in electric field, and reducing the charge transfer barrier. Among them, the optimum DC/PDI (2:1) with enlarged D–A enables to capture the largest number of electrons for persulfate activation, and concurrently affords the highest hole generation efficiency with the deepest valence band (1.67 V). Such merits contribute to 1.2–2.8 times higher degradation rate and 1.1–1.6 times higher mineralization rate of organic pollutants in comparison with other counterparts. The mineralization rate can reach 100% in the engineered microreactor setup. This study elucidates the structure‐mechanism‐performance relationship of D–A modulation and charge separation/transport, guiding the rational molecular structure design for efficient photocatalytic oxidation.