Ordered Ionic Nanochannels in Covalent Organic Frameworks for Photosynthesis of H ₂ O ₂ From Ambient Air‐Equilibrated Water

Abstract

ABSTRACT Covalent organic frameworks (COFs) hold great promise for photosynthetic H 2 O 2 but suffer from limited water/oxygen transport dynamics and low electron utilization efficiency. Herein, we report efficient solar‐driven H 2 O 2 production directly from ambient air‐equilibrated water using ionic vinylene‐linked covalent organic frameworks (ivCOFs). Guided by electron donor‐acceptor (EDA) complexation, we synthesize highly crystalline ivCOFs with permanent porosity and well‐defined ionic nanochannels entirely in water. The resulting ivCOFs synergistically integrate ultrafast water transport and robust Pauling‐type O 2 adsorption. Notably, the embedded ionic groups modulate the electronic band structure, effectively suppressing the hydrogen evolution side reaction and enhancing both thermodynamic driving force and selectivity for the 2e − oxygen reduction to H 2 O 2 . Consequently, ivCOF‐I achieves a high H 2 O 2 production rate of 6.9 mmol g −1 h −1 , an apparent quantum yield of 15.7%, and a solar‐to‐chemical efficiency of 1.08%, all using only air and water. It operates stably in both batch and continuous‐flow systems (> 120 h), retaining structural integrity. Mechanistic studies confirm concurrent 2e − water oxidation and oxygen reduction pathways. This work underscores the pivotal role of EDA complexes in stabilizing ionic building blocks and offers a rational design paradigm for sustainable solar‐driven chemical production.