Theory-Driven Design and Targeting Synthesis of a Highly-Conjugated Basal-Plane 2D Covalent Organic Framework for Metal-Free Electrocatalytic OER

It is a great challenge to obtain oriented design and synthesis of new two-dimensional covalent organic frameworks (2D-COFs) with proper CN stoichiometry, N position, and band structures as specific electrocatalysts. Driven by density functional theory (DFT) calculations, we designed and synthesized a new phenazine-linked 2D-COF (COF-C4N) by solvothermal reaction of triphenylenehexamine (TPHA) and hexaketocyclohexane (HKH). Structural analysis confirmed that COF-C4N possesses an ordered crystalline structure with a highly conjugated basal plane and better stability. COF-C4N exhibited OER performance with a low overpotential of 349 mV at 10 mA cm–2 and a Tafel slope of 64 mV dec–1. A combination of theoretical and experimental studies revealed that better OER performance is attributed to better crystallinity and stability, an appropriate band gap, and an N position that promotes the formation of C active sites around N atoms. The strategy of theory-driven design and targeting synthesis of 2D-COFs for OER may provide a new way to further develop metal-free materials for clean energy application.