Solvothermal Synthesis of Uniform Covalent Organic Framework Microspheres Enabling High-Loading Palladium for Oxygen Reduction Reaction

Abstract

Although the solvothermal synthesis has become a prevailing strategy for the preparation of diverse spherical covalent organic frameworks (COFs), synthesis of uniform COF microspheres has still been a grand challenge due to the uncontrollable kinetics. Herein, we introduced 2,4,6-trimethylbenzaldehyde (TBA) as a molecular regulator in the reaction system, where the size and uniformity of spherical COFs were controlled by dynamic reversibility of imine exchange between TBA and building units and depended on the addition amount, molecular structure, and synthesis temperature. The applicability of the synthetic strategy was demonstrated by varying different structural units. Moreover, imine linkages of COF microspheres function as active sites suitable for coordinating with Pd single atoms and atomic clusters to promote electron transfer and synergistically enhance electrocatalytic oxygen reduction reaction. This work addressed the problems of poor uniformity and untunable size of COF spheres previously faced by the solvothermal method, thereby providing guidance for the construction of spherical COF-based catalyst supports.

Research Progress on the Application of Covalent Organic Framework Nanozymes in Analytical Chemistry

“…Among them, the concentration of the catalyst, reaction time, temperature, and pressure all affect the structure and activity of COF nanozymes. Based on the solvothermal synthesis method, researchers have conducted a lot of work on the performance of COF nanozymes [68,69]. Solvothermal synthesis is widely used and is conducive to the large-scale preparation of COF nanozymes [65].…”

The Cutting‐Edge Progress in Covalent Organic Framework‐Based Nanomedicine

“…These versatile synthesis methods encompass solvothermal reactions, microwave-assisted procedures, ionothermal routes, interface-driven techniques, room temperature synthesis, electrochemical synthesis as well as mechanical grinding methodologies. [11][12][13][14][15][16][17] In the treatment of advanced cancer, chemotherapy is the most commonly used antitumor method. Chemotherapeutic drugs are typically administered intravenously or orally, affecting the entire body, which often leads to systemic side effects such as nausea and vomiting in patients.…”