Precisely Regulating the Three-Dimensional Morphology of COF-Based Architecture via the Alloy-Embedding Strategy as Efficient Photocatalysts

The construction of covalent organic frameworks (COFs) with distinct three-dimensional (3D) structures is crucial to explore the structure–activity relationship and expand potential applications. Herein, we propose a facile strategy to fabricate a COF snowflake, nanofiber, and nanosphere by introducing Au–Ag, Hg–Ag, and Pd–Ag alloys into the structure of phenanthroline-functionalized COF (PA-COF) via ordered reduction of metal ions by a phenanthroline moiety. The final morphologies of 3D PA-COF architectures depend critically on the assembly mode of COF modules, driven by the lattice mismatch as well as the distinct metal autocatalytic activities of the three different alloys. A machine learning model trained on limited data was adopted to guide the construction of a Au–Ag embedded COF snowflake (PA-COF-SF). The obtained PA-COF-SF showed excellent degradation performance to sulfamethoxazole (SMX) with a high-rate constant of 0.0606 min–1, due to the significantly enhanced charge transfer and separation efficiency contributed by the embedded Au–Ag alloy and the unique 3D snowflake architecture. Attributed to the strong interactions between Au/Ag atoms and the phenanthroline moiety, PA-COF-SF exhibited favorable homogeneity and remarkable stability, maintaining an 88.5% removal rate of SMX after 20 cycles. This work revealed the construction mechanism of a COF with a unique 3D architecture and provides insights into the structure–activity relationship of the COF materials.