Proper design and preparation of high-performance and stable dual functional photocatalytic materials remains a significant objective of research. In this work, highly dispersed Pd nanoparticles of about 3–6 nm in diameter are immobilized in the metal-organic framework (MOF) UiO-66(NH₂) via a facile one-pot hydrothermal method. The resulting Pd@UiO-66(NH₂) nanocomposite exhibits an excellent reusable and higher visible light photocatalytic activity for reducing Cr(VI) compared with UiO-66(NH₂) owing to the high dispersion of Pd nanoparticles and their close contact with the matrix, which lead to the enhanced light harvesting and more efficient separation of photogenerated electron–hole pairs. More significantly, the Pd@UiO-66(NH₂) could be used for simultaneous photocatalytic degradation of organic pollutants, like methyl orange (MO) and methylene blue (MB), and reduction of Cr(VI) with even further enhanced activity in the binary system, which could be attributed to the synergetic effect between photocatalytic oxidation and reduction by individually consuming photogenerated holes and electrons. This work represents the first example of using the MOFs-based materials as dual functional photocatalyst to remove different categories of pollutants simultaneously. Our finding not only proves great potential for the design and application of MOFs-based materials but also might bring light to new opportunities in the development of new high-performance photocatalysts.

Metal–organic frameworks (MOFs) have been arousing a great interest owing to their unique physicochemical properties. In this work, Zr-benzenedicarboxylate (UiO-66) and its derivative, Zr-2-NH₂-benzenedicarboxylate (UiO-66(NH₂)), are successfully prepared via a facile solvothermal method and applied to photocatalytic reactions. Powder X-ray diffraction (XRD) confirms the isoreticular nature of UiO-66 and UiO-66(NH₂), while Fourier transformed infrared spectra (FTIR) prove the effective presence of amino group. UV-vis diffuse reflectance spectra (DRS) show the photoabsorption edge of UiO-66 could be shifted to the visible light region by simply introducing the amino group (–NH₂) on the organic ligand. Importantly, UiO-66(NH₂) is proved to perform as an efficient multifunctional visible-light-driven photocatalyst with high stability and considerable recyclability in both the photocatalytic selective oxidation of alcohols to aldehydes using molecular oxygen as oxidant and catalytic reduction of aqueous Cr(VI) to Cr(III) under ambient conditions. Furthermore, the possible reaction mechanism has also been investigated in detail. This work makes a systematic attempt to understand the reaction of photocatalytic selective oxidation of alcohols over MOFs and represents the first example to report the identification of MOFs as promising visible-light photocatalysts toward reduction of aqueous Cr(VI). More significantly, our finding also provides a new way to design MOFs-based photocatalysts, that is, by tuning the predesigned ligands with specific functional groups, the optical absorption properties of MOFs can be flexibly modulated, and then the effective solar energy conversion can be expected.

CdS nanorods have been successfully decorated on the surface of MOF (metal–organic framework) UiO–66(NH₂) via a facile room-temperature photodeposition technique in a controlled manner. Electrochemical measurements indicate that the CdS photodeposition proceeds via the preferential reduction of Cd ions to Cd⁰ followed by chemical reaction with S₈. The photocatalytic performances of the obtained CdS–UiO–66(NH₂) nanocomposites have been evaluated by selective oxidation of various alcohol substrates using molecular oxygen as a benign oxidant. The results show that such CdS–UiO–66(NH₂) nanocomposites exhibit considerable photocatalytic activity and stability, which may be due to the large specific surface area and the charge injection from CdS into UiO–66(NH₂) leads to efficient and longer charge separation by reducing the recombination of electron–hole pairs. This work represents the first example of using MOFs not only as supports but also as electron providers to trigger the reaction for coupling MOFs with metal sulfides, thus fabricating novel MOF–CdS nanocomposite systems and improving their photocatalytic activity. It is hoped that our findings could offer useful information and open a new window for the design of novel MOF–semiconductor nanocomposites as efficient visible light driven photocatalysts.

UiO-66-X (X = H, NH₂, NO₂, Br) have been successfully synthesized and tested for their photocatalytic activity in water treatment. Results show that electronic effect of the ligand substituents greatly affects the photocatalytic activity of UiO-66. The rates obtained by different substituents are linearly correlated with their Hammett coefficients.