Yu-Peng Yuan

Thiol-functionalization of metal-organic framework by a facile coordination-based postsynthetic strategy and enhanced removal of Hg2+ from water

The presence of coordinatively unsaturated metal centers in metal-organic frameworks (MOFs) provides an accessible way to selectively functionalize MOFs through coordination bonds. In this work, we describe thiol-functionalization of MOFs by choosing a well known three-dimensional (3D) Cu-based MOF, i.e. [Cu(3)(BTC)(2)(H(2)O)(3)](n) (HKUST-1, BTC=benzene-1,3,5-tricarboxylate), by a facile coordination-based postsynthetic strategy, and demonstrate their application for removal of heavy metal ion from water. A series of [Cu(3)(BTC)(2)](n) samples stoichiometrically decorated with thiol groups has been prepared through coordination bonding of coordinatively unsaturated metal centers in HKUST-1 with -SH group in dithioglycol. The obtained thiol-functionalized samples were characterized by powder X-ray diffraction, scanning electron microscope, energy dispersive X-ray spectroscopy, infrared spectroscopy, and N(2) sorption-desorption isothermal. Significantly, the thiol-functionalized [Cu(3)(BTC)(2)](n) exhibited remarkably high adsorption affinity (K(d)=4.73 × 10(5)mL g(-1)) and high adsorption capacity (714.29 mg g(-1)) for Hg(2+) adsorption from water, while the unfunctionalized HKUST-1 showed no adsorption of Hg(2+) under the same condition.

Hetero-nanostructured suspended photocatalysts for solar-to-fuel conversion

Converting solar energy into valuable hydrogen and hydrocarbon fuels through photocatalytic water splitting and CO2 photo-reduction is highly promising in addressing the growing demand for renewable and clean energy resources. Developing efficient photocatalysts for solar-driven H2 production and CO2 reduction is the most essential part in achieving this goal. For the purpose of attaining high photocatalytic efficiency, hetero-nanostructures formed by multiple material components have been demonstrated as an effective strategy. Within this heterostructure, its interface is a critical consideration, whereby it determines the principle of charge transfer across the heterojunctions and consequent surface reactions. This article reviews the recent developments of hetero-nanostructures for photocatalytic H2 production and CO2 reduction based on material compositions that form heterojunctions.

Fe3O4@MOF core–shell magnetic microspheres with a designable metal–organic framework shell

A novel kind of porous microsphere with a magnetic core and a tunable metal–organic framework (MOF) shell has been successfully fabricated utilizing a versatile step-by-step assembly strategy. The structure, composition, and function of the microspheres can be judiciously tailored by choosing various metal ions and polyfunctional organic ligands or tuning the assembly processes. Our results provide a valuable methodology for rationally designing novel core–shell architectures and MOF-based porous magnetic platforms.

Facile fabrication of magnetic metal–organic framework nanocomposites for potential targeted drug delivery

In this paper, we describe a facile, efficient, and environmentally friendly fabrication of a novel type of magnetic porous metal–organic-framework (MOF)-based nanocomposites that can be potentially used for targeted drug delivery. The magnetic MOF nanocomposites were fabricated by incorporation of Fe3O4 nanorods with nanocrystals of Cu3(BTC)2 (HKUST-1), a three dimensional (3D) MOF with a 3D channel system. The as-synthesized materials exhibited both magnetic characteristics and high porosity, making them excellent candidates for targeted drug delivery systems. An anti-cancer drug acting as a selective cyclooxygenase-2 (COX-2) inhibitor for pancreatic cancer treatment, Nimesulide, was laden into pores of the nanocomposites. These MOF-based magnetic nanocomposites could adsorb up to 0.2 g of Nimesulide per gram of composite, and it took as long as 11 days to complete the drug release in physiological saline at 37 °C.

New photocatalysts based on MIL-53 metal-organic frameworks for the decolorization of methylene blue dye.

The photocatalytic decolorization of methylene blue dye in aqueous solution using a novel photocatalyst MIL-53(Fe) metal-organic frameworks was investigated under UV-vis light and visible light irradiation. The effect of electron acceptor H(2)O(2), KBrO(3) and (NH(4))(2)S(2)O(8) addition on the photocatalytic performance of MIL-53(Fe) was also evaluated. The results show that MIL-53(Fe) photocatalyst exhibited photocatalytic activity for MB decolorization both under UV-vis light and visible light irradiation, and the MB decolorization over MIL-53(Fe) photocatalyst followed the first-order kinetics. The addition of different electron acceptors all enhances the photocatalytic performance of MIL-53(Fe) photocatalyst, and the enhanced rate follows the order of H(2)O(2)>(NH(4))(2)S(2)O(8)>KBrO(3) under UV-vis light irradiation, while in the order of (NH(4))(2)S(2)O(8)>H(2)O(2)>KBrO(3) under visible light irradiation. Moreover, MIL-53(Fe) did not exhibit any obvious loss of the activity for MB decolorization during five repeated usages. The photocatalytic activities over MIL-53(M) (M=Al, Fe), the isostructure to MIL-53(Fe), indicate that the metal centers show nil effect on the photocatalytic activity of MIL-53(M) photocatalysts.

A novel magnetic recyclable photocatalyst based on a core–shell metal–organic framework Fe3O4@MIL-100(Fe) for the decolorization of methylene blue dye

We describe a novel type of magnetic recyclable Fe3O4@MIL-100(Fe) photocatalyst on the basis of a porous metal–organic framework (MOF) and its photocatalytic activities in the photodegradation of methylene blue (MB) dye. It was found that Fe3O4@MIL-100(Fe) exhibited photocatalytic activity for MB dye degradation under both UV-vis and visible light irradiation, and the MB decolorization over the Fe3O4@MIL-100(Fe) photocatalyst followed first-order kinetics. Moreover, it can be easily separated and recycled without significant loss of photocatalytic activity after being used many times. Therefore, compared to the conventional photocatalysts of TiO2 and C3N4 used in the photocatalytic degradation of dye, this magnetic core–shell photocatalyst is green, cheap and more suitable for large scale industrial applications.

Facile fabrication of magnetically separable graphitic carbon nitride photocatalysts with enhanced photocatalytic activity under visible light

Because of their potential application in the conversion of solar energy to chemical energy, the development of semiconductor photocatalysts that have high reactivity under visible light has received great attention. In the present work, we illustrate the design and fabrication of magnetically separable polymeric carbon nitride photocatalysts, i.e. Fe2O3/g-C3N4 composite photocatalysts, a novel type of visible light driven photocatalyst with a cost-effective recovery manner. The obtained Fe2O3/g-C3N4 composite catalysts with different Fe2O3 contents were characterized by powder X-ray diffraction (PXRD), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflection spectroscopy (DRS), vibration sample magnetometry (VSM) and thermogravimetric analysis (TGA). The saturation magnetization at 300 K varies from 0.37 to 1.56 emu g−1, depending on the different Fe2O3 contents (2.8–11.6 wt%) in the Fe2O3/g-C3N4 composites, clearly indicating the excellent magnetic separation characteristics of the as-prepared photocatalysts. Remarkably, the photocatalytic activity of the magnetic Fe2O3/g-C3N4 photocatalysts under visible light irradiation was increased up to 1.8 times for the photodegradation of Rhodamine B (RhB) under visible light irradiation compared with the conventional pure g-C3N4 photocatalyst. A possible mechanism for the enhanced photocatalytic activity of the Fe2O3/g-C3N4 composite photocatalyst was also proposed to guide the further improvement of their photocatalytic activity.

Rapid synthesis of nanoscale terbium-based metal–organic frameworks by a combined ultrasound-vapour phase diffusion method for highly selective sensing of picric acid

A combined ultrasound-vapour phase diffusion technique was used for the rapid synthesis of a terbium-based metal–organic framework (MOF), [Tb(1,3,5-BTC)]n. Compared with conventional solvothermal and ultrasound-assisted methods, such a kind of combined ultrasound-vapour phase diffusion technique is highly sufficient for synthesizing nanoscale MOF crystals in remarkably high yields. Significantly, the as-prepared [Tb(1,3,5-BTC)]n nanocrystals exhibited highly selective sensing of picric acid (PA) without the interference of other nitroaromatic compounds such as nitrobenzene, 2-nitrotoluene, 4-nitrotoluene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene. This makes them a potential candidate for developing novel luminescence sensors for the highly selective sensing of PA.

Hierarchically mesostructured MIL-101 metal–organic frameworks: supramolecular template-directed synthesis and accelerated adsorption kinetics for dye removal

Hierarchically mesostructured MIL-101 metal–organic frameworks (MOFs) were successfully synthesized under solvothermal synthesis conditions by using the cationic surfactant cetyltrimethylammonium bromide as a supramolecular template. The mesostructured MIL-101 MOFs were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption isotherms at 77 K. The results suggest that the mesostructured MIL-101 MOFs obtained are composed of numerous MOF nanocrystals. Pore size distribution analyses of the as-synthesized MOF samples reveal that such mesostructured MIL-101 MOFs have well-defined trimodal pore size distributions showing simultaneous existence of meso- and macropore channel systems. Significantly, such hierarchically mesostructured MIL-101 exhibits remarkably accelerated adsorption kinetics for dye removal in comparison with the bulk MIL-101 crystals, which is due to unique hierarchically meso- and macropores created in the solid.

Enhanced visible-light-driven photocatalytic hydrogen generation over g-C3N4 through loading the noble metal-free NiS2 cocatalyst

Nickel sulfide nanoparticles were successfully grown as a cocatalyst on the surface of polymeric g-C3N4 photocatalysts through a hydrothermal method. The NiS2 composition is confirmed by various spectroscopic techniques and electron microscopy. It was found that the presence of NiS2 nanoparticles on the g-C3N4 surface could greatly enhance the photocatalytic activity of g-C3N4 for hydrogen generation under visible-light irradiation. Significantly, the NiS2-loaded g-C3N4 was capable of showing an even higher photocatalytic H2 generation rate than that of Pt-loaded g-C3N4. Such enhanced photocatalytic activities by NiS2-loading could be attributed to the effective charge transfer between g-C3N4 and the attached NiS2 nanoparticles which might also serve as active sites for proton reduction into H2. Our studies demonstrate a promising strategy to develop economic noble-metal-free composites as photocatalysts for efficient solar-to-hydrogen conversion.