Isoelectronic Organic Dye-Based Covalent Organic Framework with Varied Nitrogen Content for Tuning Optoelectronic Properties and Photocatalytic H2 Evolution

The classical organic dyes anthracene, acridine, and phenazine, as building blocks in the construction of three covalent organic frameworks (COFs), are presented for comprehensive comparison studies. Employing a sophisticated atomic-level skeleton-editing strategy through the precise adjustment of nitrogen content enables the regulation of intrinsic properties across macro- to micro-scales, encompassing color, morphology, thermal stability, charge separation, transfer dynamics, energy level position, and photocatalytic performance, among others. Extensive characterization technologies and density functional theory (DFT) calculations are elaborately performed to illustrate the "butterfly effect", wherein atomic-level "flapping of the wings" within COF materials can significantly impact other aspects. In application experiments, photocatalytic hydrogen evolution (PHE) is studied as a model reaction. The results suggest that the anthracene-based COF (COF-Ant), with the strongest electron-donating ability, achieves the highest PHE rate among the three COFs at 2493 μmol·g–1·h–1. Additionally, the uniformity of the three COFs is highlighted, including shared features such as organic dyes and imine linkages, resulting in wide visible absorption, a narrow band gap, and topological features. This work offers a promising outlook for the rational construction of donor–acceptor (D–A) frameworks through atomic-level engineering, facilitating the customization of optoelectronic, photocatalysis, and other properties.