Bimetallic Co/Zn zeolitic imidazolate framework ZIF-67 supported Cu nanoparticles: An excellent catalyst for reduction of synthetic dyes and nitroarenes.

In this study, a sub-class of microporous crystalline metal organic frameworks (MOFs) with zeolite-like configurations, i.e., zeolitic imidazolate frameworks of single node ZIF-67 and binary nodes ZIF-Co/Zn are used as the supports to develop Cu nanoparticles based nanocatalysts. Their catalytic activities are comparatively evaluated where Cu(x)@ZIF-Co/Zn exhibits better performances than Cu(x)@ZIF-67 in the reduction of synthetic dyes and nitroarenes. For instance, the Cu(0.25)@ZIF-Co/Zn catalyst shows an excellent reaction rate of 2.088 × 10-2 s-1 and an outstanding activity of 104.4 s-1gcat-1 for the reduction of methyl orange. The same catalyst also performs an exceptional catalytic activity in the hydrogenation of p-nitrophenol to p-aminophenol with the activity of 216.5 s-1gcat-1. A synergistic role of unique electronic properties rising from the direct contact of Cu NPs with the bimetallic nodes ZIF-Co/Zn, higher surface area of support, appropriate Cu loading and maintainable microporous frameworks with higher thermal and hydrolytic stability collectively enhances the catalytic activity of Cu(x)@ZIF-Co/Zn. Moreover, this catalyst shows excellent stability and recyclability, which can retain high conversion after reuse for 10 cycles.

Insight into the Superior Lithium Storage Properties of Ultrafine CoO Nanoparticles Confined in a 3 D Bimodal Ordered Mesoporous Carbon CMK-9 Anode.

Ultrafine CoO particles immobilized into the mesopores of three-dimensional cubic bimodal ordered mesoporous carbon CMK-9 is successfully prepared by using a combination of nanocasting and wet-impregnation methods. It is found that the cubic bimodal interconnected mesoporous framework of CMK-9 plays a crucial role in achieving the excellent electrochemical performances by assisting the rapid mass and charge transfer. Among the prepared nanocomposites, CoO(10)@CMK-9 delivers a discharge capacity of 830 mAh g-1 after 200 cycles at a current density of 100 mA g-1 in lithium-ion batteries. At a higher current density of 1000 mA g-1 , the anode presents an outstanding discharge capacity of 636 mAh g-1 after 200 cycles. In sodium-ion batteries, the anode provides a discharge capacity of 296 mAh g-1 after 250 cycles at a current density of 100 mA g-1 . The remarkable performances of CoO(10)@CMK-9 demonstrate the promising potentials of the nanocomposite as the anode for rechargeable batteries.

Ultrafine bimetallic Ag-doped Ni nanoparticles embedded in cage-type mesoporous silica SBA-16 as superior catalysts for conversion of toxic nitroaromatic compounds.

Highly active Ag-doped Ni nanoparticles are successfully fabricated within carboxylic acid (-COOH) functionalized mesoporous silica SBA-16 by a facile wet incipient technique for catalytic conversion of toxic nitroaromatics. The -COOH groups on SBA-16 play a crucial role by enhancing the electrostatic interactions with Ag(I)/Ni(II) cations, that control the crystal growth during the thermal reduction. Systematic characterizations of SBA-16C and Agx%Ni@SBA-16C are performed by different techniques including solid state 13C and 29Si nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), N2 sorption, X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and superconducting quantum interference device (SQUID). The highly dispersed ultrafine Ag-doped Ni NPs (∼3 nm) are well-confined within SBA-16C and exhibit magnetic properties that are extremely beneficial for recycling. The bimetallic Ag2.4%Ni@SBA-16C shows exceptionally high catalytic activity during catalytic conversion of toxic nitroaromatics to environmentally friendly amino-aromatics. The enhanced catalytic activity could be ascribed to the combined effects of unique electronic properties, synergistic effects of Ag-doped Ni, ultra-small size, metal loading, and favorable textural properties. These magnetically separable nanocatalysts show excellent durability.

Confinement of Cu nanoparticles in the nanocages of large pore SBA-16 functionalized with carboxylic acid: enhanced activity and improved durability for 4-nitrophenol reduction.

Carboxylic acid (-COOH) functionalized large pore mesoporous silica SBA-16 is prepared and utilized as the support to synthesize Cu nanoparticles (NPs). The interaction between the -COOH groups in the support and the metal precursors effectively controls the dispersion and size of the Cu NPs. The Cu NP encapsulated large pore SBA-16 is used as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The catalyst shows an excellent reaction rate of 1.55 × 10-2 s-1 and an outstanding activity of 950 s-1 g-1. The prominent catalytic activity can be attributed to the nanoscale dimension of the Cu NPs (ca. 5 nm) and their homogeneous distribution, and the 3D pore architecture of the support that allows easy transportation of the reactants. The cage-type mesopores of the support SBA-16 also effectively prevent aggregation and leaching of Cu NPs, and thus exhibit similar catalytic activity for several cycles, indicative of its superb durability.

pH responsive selective protein adsorption by carboxylic acid functionalized large pore mesoporous silica nanoparticles SBA-1.

Cubic mesoporous silica nanoparticles (MSNs) with the SBA-1 moiety, functionalized with carboxylic acid (COOH) groups as well as enlarged mesopores, are successfully synthesized using tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) as silica sources, complexes formed by polyacrylic acid (PAA) and hexadecylpyridinium chloride (CPC) as templates, and trimethylbenzene (TMB) as pore expander. The successful incorporation of organic functionalities are confirmed by 13C and 29Si solid-state NMR. The structural properties of cubic mesostructures are characterized by powder XRD, N2 adsorption-desorption isotherms, and TEM measurements. The prepared MSNs exhibit a remarkably high adsorption capacity of 1138 mg g-1 at pH 8.2 when they are used as the supports to immobilize papain. Both factors of the large pore size of the support and the favorable electrostatic attractions between the carboxylate groups on the adsorbent surface and the papain molecules play important roles in reaching such a high adsorption capacity. The immobilized papain possesses better thermal stability, pH tolerance, and heat resistance in comparison to the free papain. The materials are also used for selective adsorption of a single protein (papain) from the binary mixture of two different types of proteins (papain and hemoglobin). Our results demonstrate that proteins such as papain and hemoglobin with different isoelectric points and shapes can be effectively separated from their binary mixture by simply tuning the pH of the buffer.

Carboxylic acid Functionalized Cage-Type Mesoporous Silica FDU-12 as Support for Controlled Synthesis of Platinum Nanoparticles and Their Catalytic Applications.

Carboxylic acid functionalized 3D cage-type mesoporous silica FDU-12 with high surface area and pore volume was synthesized by a one-pot co-condensation method and used as support to synthesize Pt nanoparticles (NPs). The uniformly distributed COOH groups in the cage can control the growth of Pt NPs with high dispersion (Pt@CF-12). Pt@CF-12 was used as catalyst for the hydrolysis of ammonia borane to generate H2 and for the reduction of 4-nitrophenol to 4-aminophenol. The catalyst exhibits higher catalytic activity (H2 generation rate of 17.8 L H2 min-1 gcat-1 ) and lower activation energy of 30.67 kJ mol-1 compared with other Pt-based silica catalysts due to the small size of the Pt NPs (3.5 nm) and cage-type porous structure of the support, which allowed easy diffusion of reactants. Pt@CF-12 has excellent durability, since the support prevented NP aggregation and leaching of NPs during catalysis. Pt@CF-12 can convert 93 % of 4-nitrophenol to 4-aminophenol within 10 min.

Bifunctional Cage-Type Cubic Mesoporous Silica SBA-1 Nanoparticles for Selective Adsorption of Dyes.

Bifunctional SBA-1 mesoporous silica nanoparticles (MSNs) with carboxylic acid and amino groups (denoted as CNS-10-10) have been successfully synthesized, characterized, and employed as adsorbents for dye removal. Adsorbent CNS-10-10 shows high affinity towards cationic and anionic dyes in a wide pH range, and exhibits selective dye removal of a two-dye mixture system of cationic methylene blue and anionic eosin Y. By changing the pH of the medium, the selectivity of the adsorption behavior can be easily modulated. For comparison purposes, the counterparts, that is, pure silica SBA-1 MSNs (CS-0) and those with either carboxylic acid or amino functional groups (denoted as CS-10 and NS-10, respectively) were also prepared to evaluate their dye-adsorption behaviors. As revealed by the zeta-potential measurements, the electrostatic interaction between the adsorbent surface and the dye molecule plays an important role in the adsorption mechanism. Adsorbent CNS-10-10 can be easily regenerated and reused, and maintains its adsorption efficiency up to 80 % after four cycles.

The influence of residual stress on the shear strength between the bone and plasma-sprayed hydroxyapatite coating.

Plasma-sprayed HA coating (HAC) 50 and 200 microm thick on Ti6Al4V cylinders was transcortically implanted in the femora of canines. Push-out testing of implant-bone interfaces showed that the HAC coating exhibited higher shear strength at 50 microm coating than 200 microm one. The plasma-sprayed HACs were exhibited compressive residual stresses and the thicker HAC exhibited higher residual stress than that of the thinner HAC. Due to the structure for 50 and 200 microm implants were the same, meaning similar cohesive strength of the lamellar splats. And, there was no difference in the physiological environment; hence the difference of the shear strength for the 50 and 200 microm-HAC implants could best be attributed to the compressive residual stress existed in the HA coating.