Chirality-Induced Selective Electrosynthesis Hydrogen Peroxide and Tandem Green Chemical Synthesis.

Two-electron oxygen reduction reaction (2e--ORR) toward hydrogen peroxide (H2O2) suffers from sluggish O─O preservation and spin-forbidden triplet O2-to-singlet H2O2 transition. Herein, we resolve this pivotal challenge by leveraging the chirality-induced spin selectivity (CISS) effect in inherently chiral Salen covalent organic frameworks (C-Salen-COFs-Zn) as 2e--ORR electrocatalysts. The CISS effect imparts uniform surface electron spin polarization to the C-Salen-COFs-Zn, whereby triplet O2 bearing two parallel-spin electrons readily accepts opposite-spin electrons, alleviating the spin-forbidden transition to promote the generation of H2O2. The C-Salen-COF-Zn exhibits exceptional spin selectivity with CISS-induced spin polarization efficiency exceeding 90%, delivering superior electrocatalytic performance to its achiral counterpart. C-Salen-COF-Zn achieves 87.0% H2O2 selectivity, 297.7 mmol g-1 h-1 production rates at 0.2 V versus RHE, and Faradaic efficiencies up to 93.7% at 0.6 V versus RHE in H-type cell. Flow-cell system achieves 1169.7 and 1207.6 mmol g-1 h-1 H2O2 yield for C-Salen-COF-Zn. Comprehensive mechanistic studies reveal that C-Salen-COF-Zn preferentially adopts a Pauling-type adsorption mode, favoring •O2 - formation by partially filling the π* antibonding orbitals, preserving the O─O bond. The spin-selective C-Salen-COF-Zn was integrated into a closed-loop cascade system for on-demand H2O2 generation and utilization, delivering 72% sodium perborate, 56% sodium peroxycarbonate, 82.7% lignin-to-benzoic acid conversions, and electro-Fenton degradation in advanced oxidation processes.