Halogen atom-induced local asymmetric electron in covalent organic frameworks boosts photosynthesis of hydrogen peroxide from water and air

Abstract

The solar-to-chemical conversion (SCC) efficiency of hydrogen peroxide (H₂O₂) photosynthesis is governed by the O₂ adsorption model and energy level, which are experimentally challenging to be tuned. Herein, we report a new strategy for tuning of the O₂ adsorption and electron potential energy level of covalent organic frameworks (COFs) using halogen atom (F, Cl, Br, and I) as a regulatory reagent, and demonstrate that I-COFs exhibit the maximum thermodynamic driving force for 2e^– oxygen reduction reaction (ORR). The introduction of I atom inhibits the O–O bond breakage for enhancing the selectivity of 2e^– ORR from 56.5% to 87.0%, thus promoting the continuous natural sunlight-driven photosynthesis of H₂O₂ directly from water and air, showing a high SCC efficiency of 1.88% and the operational stability of over 200 h. Meanwhile, I-COFs also show 100% antibacterial performance and efficient wound healing ability, which is significantly better than that of H-COFs with symmetric electron distribution.