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.