Inductive effect reversal drives efficient photocharging of catalytic sites in polymeric catalysts for continuous-flow H2O2 synthesis.

Polymeric photocatalysts show great promise for solar-driven H2O2 production, yet their structural-electronic correlations and scalability remain insufficiently elucidated. Herein, we reveal the pivotal role of the inductive effect in polymeric semiconductors. Cyano groups polarize the π-conjugated network in crystalline carbon nitride (CCN), generating a negative inductive effect that enhances charge dynamics and O2 adsorption but limits electron availability for oxygen reduction. Introducing ether linkages into ordered CCN chains (OCCN) reverses this effect, further facilitating charge separation and lowering the barrier for *OOH intermediate formation. Notably, the resulting positive inductive effect enables efficient photocharging of cyano groups with hot electrons. Consequently, OCCN delivers a remarkable H2O2 yield of 13 136.4 µmol g-1 h-1 in water, even higher performance in seawater, and sustains 110.4 µmol h-1 generation in continuous flow. These findings establish inductive effect engineering as a powerful approach for advancing polymeric photocatalysts toward scalable solar-to-chemical conversion.