Enhanced Properties and Stability of Block-MOFs for Electrochemical Reduction through Tuning the Defective Sites

Abstract The poor electrical conductivity and insufficient active sites of MOFs severely restrict their electrocatalytic applications. Herein, tannic acid (TA), a polyhydroxy molecule, was used to etch the surface of MIL-101(Fe). The hydroxyl groups chelate with exposed Fe sites to stabilize active centers and improve electrocatalytic durability. Among TA-modified MIL-101(Fe) samples with different reaction durations, MIL-101(Fe)-1h delivers nearly full conversion, high Faradaic efficiency, and excellent selectivity for electrochemical nitrobenzene hydrogenation. Control experiments confirm that the TA-etching strategy creates abundant active sites, enhances stability, and modulates the local microenvironment for boosted catalytic performance.