Linker scissoring strategy enables precise shaping of Fe/Mn-MOF to construct S-scheme heterojunction with Bi2S3 for enhanced photoexcitation under peroxymonosulfate activation

Abstract

Metal-organic frameworks (MOFs) with controllable shapes and sizes exhibit tremendous potential in environmental remediation. However, the synergistic effects between shape and photocatalytic performance have not been fully established. Herein, a tailored strategy of ligand trimming through acetic acid-regulated solvothermal methods was successfully designed to develop controlled shapes of bimetallic Fe/Mn-MOF. This approach yielded hexagonal prismatic bipyramidal crystals (HPBC), quadratic bipyramidal crystals (QBC) and hexagonal platelet crystals (HPC). This work broke through the limitations of the traditional single morphology regulation and effectively modulated the crystal growth rate, allowing for the formation of three MOF shapes. Nitrogen physisorption and photocatalytic experiments confirmed that the smaller particle size of QBC possessed the highest surface area and catalytic activity, indicating that the suitable particle size provided a higher active site. Therefore, QBC was chosen to focus on the study with the optimal morphology and integrated with Bi2S3 to construct an S-scheme heterojunction. This heterojunction facilitated efficient electron-hole separation and migration driven by the built-in electric field, significantly boosting photocatalytic activity. A superior 94.26% degradation efficiency for tetracycline was reached within 40 min via photoexcitation. Based on both experimental results and DFT theoretical calculations, the non-radical oxidation (1O2) mechanism involved in the electrophilic attack toward peroxymonosulfate (PMS) activation was discovered. This study would guide the rational design of the structure-activity heterojunction catalysts.