In Situ Construction of Pt–Ni NF@Ni‐MOF‐74 for Selective Hydrogenation of p ‐Nitrostyrene by Ammonia Borane

Highly Robust {In2}-Organic Framework for Efficiently Catalyzing CO2 Cycloaddition and Knoevenagel Condensation

To improve the catalytic performance of metal-organic frameworks (MOFs), creating higher defects is now considered as the most effective strategy, which can not only optimize the Lewis acidity of metal ions but also create more pore space to enhance diffusion and mass transfer in the channels. Herein, the exquisite combination of scarcely reported [In₂(CO₂)₅(H₂O)₂(DMF)₂] clusters and 2,6-bis(2,4-dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (H₅BDCP) under solvothermal conditions generated a highly robust nanoporous framework of {[In₂(BDCP)(DMF)₂(H₂O)₂](NO₃)}_n (NUC-65) with nanocaged voids (14.1 Å) and rectangular nanochannels (15.94 Å × 11.77 Å) along the a axis. It is worth mentioning that an In(1) ion displays extremely low tetra-coordination modes after the thermal removal of its associated four solvent molecules of H₂O and DMF. Activated {[In₂(BDCP)](Br)}_n (NUC-65Br), as a defective material because of its extremely unsaturated metal centers, could be generated by bromine ion exchange, solvent exchange, and vacuum drying. Catalytic experiments proved that the conversion of epichlorohydrin with 1 atm CO₂ into 4-(chloromethyl)-1,3-dioxolan-2-one catalyzed by 0.11 mol % NUC-65Br could reach 99% at 65 °C within 24 h. Moreover, with the aid of 5 mol % cocatalyst n-Bu₄NBr, heterogeneous NUC-65Br owns excellent universal catalytic performance in most epoxides under mild conditions. In addition, NUC-65Br, as a heterogeneous catalyst, exhibits higher activity and better selectivity for Knoevenagel condensation of aldehydes and malononitrile. Hence, this work offers a fresh insight into the design of structure defect cationic metal-organic frameworks, which can be better applied to various fields because of their promoted performance.

Chemically Bonded Plasmonic Triazole-Functionalized Au/Zeolitic Imidazole Framework (ZIF-67) for Enhanced CO2 Photoreduction

The design of functionalized metallic nanoparticles is considered an emerging technique to ensure the interaction between metal and semiconductor material. In the literature, this interface interaction is mainly governed by electrostatic or van der Waals forces, limiting the injection of electrons under light irradiation. To enhance the transfer of electrons between two compounds, close contact or chemical bonding at the interface is required. Herein, a new approach was reported for the synthesis of chemically bonded plasmonic Au NPs/ZIF-67 nanocomposites. The structure of ZIF-67 was grown on the surface of functionalized plasmonic Au NPs using 1H-1,2,4-triazole-3-thiol as the capping agent, which acted as both stabilizer of Au nanoparticles and a molecular linker for ZIF-67 formation. As a result, the synthesized material exhibited outstanding photocatalytic CO₂ reduction with a methanol production rate of 2.70 mmol h^-1  g^-1 _cat under sunlight irradiation. This work emphasizes that the diligent use of capping agents, with suitable functional groups, could facilitate the formation of intimate heterostructure for enhanced photocatalytic CO₂ reduction.

Support Morphology Effect on Selective Hydrogenation of 3-Nitrostyrene to 3-Vinylaniline over Pt/α-Fe2 O3 Catalysts

Selective hydrogenation of substituted nitroaromatic compounds is an extremely important and challenging reaction. Supported metal catalysts attract much attention in this reaction because the properties of metal nanoparticles (NPs) can be modified by the nature of the support. Herein, the support morphology on the catalytic performance of selective hydrogenation of 3-nitrostyrene to 3-vinylaniline was investigated. Pt NPs supported on octadecahedral α-Fe₂ O₃ supports with a truncated hexagonal bipyramid shape (Pt/α-Fe₂ O₃ -O) and rod-shaped α-Fe₂ O₃ supports (Pt/α-Fe₂ O₃ -R) were prepared by glycol reduction method. Detailed characterizations reveal that the electronic structure and dispersion of Pt NPs can be modified by the supports. The Pt/α-Fe₂ O₃ -O catalyst exhibited superior catalytic performance for hydrogenation of 3-nitrostyrene because of its low coordinated Pt sites and the small Pt NPs size, which is benefit from the high-index exposed surfaces of truncated hexagonal bipyramid-shaped α-Fe₂ O₃ support. The structural evolution during the catalytic reaction was investigated in detail by identical location transmission electron microscopy (IL-TEM) method, which found that the high cycling activity of Pt/α-Fe₂ O₃ -O catalyst during the cycle experiment results from the stability of Pt NPs.

Fast catalytic transfer hydrogenation of phenol to cyclohexanol over urea modified Ni@CN nanoparticles

The Ni@CN-450 catalyst prepared via direct pyrolysis of Ni-MOF-74(N) exhibited superior catalytic activity in catalytic transfer hydrogenation.

Construction of Core-Shell MOF@COF Hybrids with Controllable Morphology Adjustment of COF Shell as a Novel Platform for Photocatalytic Cascade Reactions

Recently, novel core-shell MOF@COF hybrids display excellent performance in various fields because of their inherited advantages from their parent MOFs and/or COFs. However, it is still a grand challenge to adjust the morphology of MOFs and/or COFs for consequent performance improvement. Herein, a Ti-MOF@TpTt hybrid coated with ultra-thin COF nanobelt, which is different from the fibrillar-like parent COF, is successfully synthesized through a sequential growth strategy. The as-obtained Pd decorated Ti-MOF@TpTt catalyst exhibits much higher photocatalytic performance than those of Ti-MOF, TpTt-COF, and Ti-MOF@TpTt hybrids with fibrillar-like COF shell for the photocatalytic cascade reactions of ammonia borane (AB) hydrolysis and nitroarenes hydrogenation. These can be attributed to its high BET surface area, core-shell structure, and type II heterojunction, which offers more accessible active sites and improves the separation efficiency of photo-generated carriers. Finally, the possible mechanisms of the cascade reaction are also proposed to well explain the improved performance of this photocatalytic system. This work presents a constructive route for designing core-shell MOF@COF hybrids with controllable morphology adjustment of COF shell, leading to the improved photocatalytic ability to broaden the applications of MOF/COF hybrid materials.