Regulating Electron Transfer in Vanadium-Based Metal-Organic Frameworks via the Synergy of Linker Engineering and...

Precise regulation of ligands in metal-organic frameworks (MOFs) to modulate the local electronic structure and charge distribution has become an effective strategy for optimizing their electrochemical performance. However, utilizing ligand-functionalized MOFs to activate their potential in aqueous zinc-ion batteries remains a challenge. Herein, eight ligand-functionalized X-MIL-47 (X represents the functional groups) samples are prepared using a one-pot solvothermal method. The polar substituents on the ligand regulated the electronic structure of the MOFs through inductive and conjugative effects, altering the electron density of the metal center and thereby facilitating the optimization of the Zn²⁺ insertion/extraction kinetics. The coordination environment of X-MIL-47 is analyzed using X-ray absorption fine structure spectroscopy, and the Zn²⁺ storage mechanism is thoroughly investigated through both in situ/ex situ spectroscopic techniques. The experimental results are consistent with DFT calculations, indicating that the introduction of polar substituents induces charge redistribution within the MOFs, thereby enhancing the reversibility of the redox reaction. Furthermore, a machine learning model based on the orthogonal expansion method and experimental data is developed to predict electrode material performance under varying conditions. This study provides new insights into the design of functional MOFs for energy storage applications.