Three-Dimensional Phenazine-Integrated Covalent Organic Framework for Efficient Electrosynthesis of H₂O₂ Under Neutral Conditions.

Abstract

Covalent organic frameworks (COFs) have emerged as promising electrocatalytic platforms for hydrogen peroxide synthesis due to their tunable structures and well-defined active sites. However, most COF-based catalysts are limited to two-dimensional (2D) architectures and alkaline conditions, which restrict their practical application. Herein, we report a strategy for constructing three-dimensional (3D) COFs that enable efficient H₂O₂ electrosynthesis under neutral conditions. By incorporating phenazine units as linked cores, we achieved a 3D COF with a 6-fold interpenetrated dia topology, where the torsional characteristics of phenazine promote dimensional transformation from 2D to 3D architectures. The resulting BCTA-PZDC-COF exhibits enhanced electronic properties and charge transfer dynamics compared to its benzene-linked counterpart (BCTA-TPTC-COF). The BCTA-PZDC-COF demonstrates exceptional 2e^- oxygen reduction reaction (ORR) in neutral electrolyte, achieving 91% H₂O₂ selectivity and a mass activity of 4.46 A g^-1, representing 68% and 79% improvements over the BCTA-TPTC-COF, respectively. Notably, in a flow cell configuration, the catalyst achieves an H₂O₂ production rate of 6.7 mol g^-1 h^-1 with a Faradaic efficiency of 90.6%. Theoretical studies indicate that the phenazine structure facilitates optimal adsorption of *OOH intermediates on the catalytic sites, thereby enhancing electrocatalytic performance. This work provides a strategic approach for designing COF electrocatalysts under environmentally benign conditions.