De Novo synthesis of platinum-nanoparticle-encapsulated UiO-66-NH2 for photocatalytic thin film fabrication with enhanced performance of phenol degradation.

The structural and chemical stability of UiO-66-NH2 and its simulated solar irradiation responsive characteristic make it a suitable metal-organic framework (MOF) candidate as photocatalytic material. Platinum nanoparticles (Pt NPs) are typically immobilized in MOF to enhance the photocatalytic efficiency. However, introducing high metal content in MOF with high dispersion is still challenging using conventional methods. In this paper, we present de novo synthesis of Pt@UiO-66-NH2, which can reach a highest metal content of 16 wt% with an average nanoparticle size of around 2 nm as confirmed by ICP-MS analysis and TEM images. The presence of benzoic acid plays multiple important roles in Pt@UiO-66-NH2 formation, including binding formation with Zr clusters, facilitating Pt dispersion, and being a modulator in MOF construction. In addition, the Pt@UiO-66-NH2 is fabricated on the α-Al2O3 substrate as a photocatalytic membrane reactor (PMR) for phenol degradation, which shows over 70 % removal efficiency under light irradiation and H2O2 addition. The recycle test shows that the PMR can maintain high catalytic efficiency. The facile de novo synthesis method proposed in this study enables effective immobilization of high metal content in MOF, and construction of membrane-based photocatalyst for scale-up application.