Chiralizing Covalent Organic Frameworks to Boost H2O2 Photosynthesis.

Solar-driven H2O2 photosynthesis offers a sustainable route to on-site oxidant production, yet the selective reduction of triplet O2 to spin-paired H2O2 remains kinetically challenging. Covalent organic framework (COF) photocatalysts have largely focused on charge separation and active-site reactivity, while overlooking the spin character of electrons transferred to O2. Here we discover that chiralization renders COFs significantly enhanced production of H2O2, and report a chiralization strategy for spin-regulated H2O2 photosynthesis in β-ketoenamine-linked COFs. The chiral frameworks enable spin-selective electron transport, favor the O-O-bond-preserving reduction pathway and lower the apparent kinetic barrier for H2O2 formation. Chiralization enhances H2O2 production by 38.7%-252.1% relative to achiral counterparts. A bipyridine-containing chiral COF reaches 22.8 mmol g-1 h-1 using solely water and oxygen, with an apparent quantum yield of 10.3% at 420 nm, placing it at the forefront of sacrificial-agent-free COF systems. Membrane-integrated chiral COFs enable continuous-flow H2O2 production. These findings establish chirality as a design parameter coupling spin-selective electron transport with O2 reduction pathway control, opening new directions for COF photocatalysis.