Chirality‐Induced Selective Electrosynthesis Hydrogen Peroxide and Tandem Green Chemical Synthesis

ABSTRACT

Two‐electron oxygen reduction reaction (2e ⁻ ‐ORR) toward hydrogen peroxide (H ₂ O ₂ ) suffers from sluggish O─O preservation and spin‐forbidden triplet O ₂ ‐to‐singlet H ₂ O ₂ 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 O ₂ bearing two parallel‐spin electrons readily accepts opposite‐spin electrons, alleviating the spin‐forbidden transition to promote the generation of H ₂ O ₂ . 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% H ₂ O ₂ 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 H ₂ O ₂ yield for C‐Salen‐COF‐Zn. Comprehensive mechanistic studies reveal that C‐Salen‐COF‐Zn preferentially adopts a Pauling‐type adsorption mode, favoring •O ₂ ⁻ 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 H ₂ O ₂ 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.