Single-Atom Ni Heterogeneous Catalysts Supported UiO-66 Structure: Synthesis and Catalytic Activities

Abstract

Herein, the single-atom Ni site heterogeneous catalysts supported by the UiO-66 structure (University of Oslo-66 metal organic framework) were successfully synthesized by a postsynthetic metalation method, where Ni ions are covalently attached to the missing-linker defect sites at zirconium oxide clusters (Zr6O4(OH)4) in as-prepared UiO-66 structure, [Zr6O4(OH)4(BDC)(DMF)10(OH)10] (BDC (benzene-1,4-dicarboxylate), DMF (dimethylformamide)). The structure properties of the catalysts were characterized using powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), N2 adsorption-desorption isotherms (BET), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy (PL). It was found that single-atom Ni heterogeneous catalysts supported by the UiO-66 structure, UiO-66/Ni1.0 [Zr6O4(OH)4(C8H4O4)(DMF)10(OH)8Ni2(OH)2(Cl)2], showed a sphere-like morphology with a high specific surface area as well as good thermal stability. Specifically, the as-prepared UiO-66/Ni1.0 exhibited the excellent catalytic activity and stability for 4-nitrophenol reduction in terms of low activation energy ( E a = 23.15 kJ mo l − 1 ), high turnover frequency (76.19 molecules g-1 min-1), and high apparent rate constant ( k app = 0.956 mi n − 1 ). In addition, methylene blue (MB) was also chosen as the organic dye model for catalytic reduction reaction. The k app and TOF for the reduction of MB using UiO-66/Ni1.0 were 0.787 min−1 and 33.89 × 10 20 molecules g−1 min−1, respectively.

Water adsorption performance of UiO-66 modified by MgCl2 for heat transformation applications

“…The peak at 1657 cm −1 belongs to the symmetrical stretching vibration of the carboxylic acid groups coordinated with the Zr centers. [32] The peak at 1580 cm −1 is caused by the asymmetric stretching of O-C-O in the BDC ligands, the peak at 1506 cm −1 represents the typical vibration of C=C in the benzene ring, and the strong peak at 1398 cm −1 is related to the O-C-O symmetrical stretching of the carboxylic acid group in the BDC ligand. [33] The samples of UiO-66 modified by the two methods show a similar FTIR spectrum to that of pure UiO-66, and no distinct chemical bond is observed.…”

Enhancement of the catalytic performance of UIO-66 for the CO2 synthesis of cyclic carbonate using natural nanomaterials as a carrier

“…The peak for 1049 cm −1 belongs to the Si–O–Si bending vibrational mode. 20,21 Characteristic absorption peaks from the aromatic ring and the carboxyl group can be observed in the IR spectrum of UIO-66, with the presence of C–O telescopic vibration from the carboxyl group at 1398 cm −1 , the CC bond in the benzene ring showing an absorption band at 1575 cm −1 , and peaks in the regions of 1652 and 1583 cm −1 attributed to the symmetric telescopic vibration of carboxylic acid groups coordinated to the zirconium metal center during deprotonation. 22 The stretching vibration at 3412 cm −1 indicates the presence of –OH, 669 cm −1 corresponding to the stretching vibration of the Zr–O cluster on UIO-66, and the symmetric and asymmetric stretching vibration peaks of Zr–(OC) being located at 553 cm −1 .…”

Defect-rich UiO-66@g-C3N4/Ni frameworks as efficient water splitting photocatalysts

“…Ni NPs acted as a cocatalyst in this photocatalytic hydrogen evolution system, and stabilization was through C and N of g-C 3 N 4 and -OH/OH 2 species of the UiO-66 MOF. 25,26 The structural configuration and mechanistic approach responsible for the enhanced efficiency of H 2 evolution of the eosin Y (EY) sensitized UiO-66-D@g-C 3 N 4 /Ni heterostructure were systematically investigated. The junction formed at the interface of UiO-66-D and g-C 3 N 4 creates an unobstructed route for efficient photoinduced charge transfer, promoting the efficient dissociation of photogenerated electron-hole pairs.…”