Schottky junctions and localized surface plasmon resonance synergistic effect of Pt/MIL-53(Al, Cr, or Fe) for ketoprofen degradation: Pathways, DFT calculation, mechanism and structure-activity relationships

The noble metal nanoparticles (NMNPs) in different chemical environments have different catalytic activities. The photocatalytic degradation ability of NMNPs was improved obviously by the combination with metal-organic frameworks (MOFs). By adjusting the metal center, the MOFs have the different chemical state and properties, further influence the photodegradation of the NMNPs. In this work, Pt/MIL-53(Al, Cr or Fe) composites were synthesized by a deposition method. The morphology, structure and photoelectric properties of the materials were systematically characterized and compared. The degradation experiments of ketoprofen showed that the catalytic activity was Pt/MIL-53(Al) > Pt/MIL-53(Cr) > Pt/MIL-53(Fe). The degradation pathways and intermediates of ketoprofen were analyzed by density functional theory (DFT) calculations and liquid chromatography-mass spectrometry (LC-MS). Through energy band structure and trap experiments, the synergistic effect of Schottky junctions and localized surface plasmon resonance (LSPR) was found. Under simulated sunlight, Pt NPs can both inject hot electrons into MIL-53 and capture electrons transferred from MIL-53. In addition, the structure-activity relationship of materials was firstly discussed via textural and optoelectronic properties. The full utilization of active sites and e−-h+ pairs is the key to improving the photocatalytic activity of the materials.