Low Temperature Oxidation of Carbon Monoxide over Mesoporous Au-Fe 2

Low temperature active and stable mesoporous Au (0.1, 0.2, 0.5, and 1.0 wt.%) supported α-Fe2O3 catalysts were prepared via deposition-precipitation method. The H2-pretreated catalyst with 0.5 wt.% Au loading offered CO conversion of 100% at 323 K and showed continual activity for at least 120 h. X-ray diffraction and transmission electron microscopy analysis indicate that Au species were highly dispersed as nanoparticles (20–40 nm) on the surface of α-Fe2O3 support even after thermal treatment at 773 K. The N2-physisorption measurements show that the synthesized α-Fe2O3 support and Au-Fe2O3 nanocomposites possessed mesopores with high specific surface area of about 158 m2 g−1. X-ray photoelectron spectroscopy and H2-TPR results reveal that the Au species exist in metallic and partially oxidized state due to strong interaction with the support. Effective Au-Fe2O3 interaction resulted in a high activity for Au nanoparticles, locally generated by the thermal treatment at 773 K in air

Soft-templated synthesis of mesoporous nickel oxide using poly(styrene-block-acrylic acid-block-ethylene glycol) block copolymers

In this work, we report the soft-templated preparation of mesoporous nickel oxide using an asymmetric poly(styrene-block-acrylic acid-block-ethylene glycol) (PS-b-PAA-b-PEG) triblock copolymer. This block copolymer forms a micelle consisting of a PS core, a PAA shell and a PEG corona in aqueous solutions, which can serve as a soft template. Specifically, the PS block forms the core of the micelles on the basis of its lower solubility in water. The anionic PAA block interacts with the cationic Ni ions present in the solution to generate the shell. The PEG block forms the corona of the micelles and stabilizes the micelles by preventing secondary aggregation through steric repulsion between the PEG chains. In terms of textural characteristics, the as-synthesized mesoporous NiO exhibits a large average pore size of 35 nm with large specific surface area and pore volume of 97.0 m g and 0.411 cm g, respectively. It is expected that the proposed soft-templated strategy can be expanded to other metal oxides/sulfides in the future for potential applications in gas sensors, catalysis, energy storage and conversion, optoelectronics, and biomedical applications

Visible Light Active Magnesium Silicate–Graphitic Carbon Nitride Nanocomposites for Methylene Blue Degradation and Pb²⁺ Adsorption

Magnesium silicate nanosheets (MgSiNS) and graphitic carbon nitride (g-C3N4) nanocomposites were produced by varying different weight percentages of g-C3N4. The obtained nanocomposites were characterized by various techniques such as X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), diffuse reflectance UV–vis spectroscopy (DR UV–vis), N2-physisorption, transmission electron microscopy (TEM), and X-ray photon spectroscopy (XPS). The photocatalytic activities of the nanocomposites were measured using visible light irradiation to degrade methylene blue (MB) and Pb2+ adsorption in aqueous solution. The ideal physicochemical properties such as porosity, band gap energy, and functional groups in the MgSiNS-GN20 composite (80% MgSiNS and 20 wt % of g-C3N4) offered high Pb2+ adsorption (0.005 mol/g) and excellent MB degradation efficiency (approximately 93%) at pH 7 within 200 min compared to other composites. In addition, the influences of different reaction parameters such as the effect of pH, the load catalyst, and the concentration of MB and Pb+2 ions were examined. The obtained results indicate that inexpensive and eco-friendly MgSiNS and g-C3N4 composites could be recycled several times, hence representing a promising material to purify water from both organic and inorganic contaminants

Confined synthesis of coordination frameworks inside double-network hydrogel for fabricating hydrogel-based water pipes with high adsorption capacity for cesium ions

Hydrogel-based water pipes which can capture ionic contaminants are a promising solution for achieving efficient water treatment. However, the fabrication of such unique water pipes as an ion-harvester remains a challenge. In this work, we have fabricated this kind of water pipe through the confined synthesis of coordination frameworks inside a double-network PAAm/PAMPS hydrogel. The hydrogel could trigger the partial decomposition and reduction of K-3[Fe(CN)(6)] upon heating. The released Fe3+/Fe2+ ions could react with the [Fe(CN)(6)](4)(-)/[Fe(CN)(6)](3)(-), finally producing Prussian Blue coordination frameworks inside the hydrogel. The resulting composite exhibited a high capacity for Cs+ ions (397 mg g(-1) in 10 minutes) by taking the coupling effect between the cation-selective hydrogel and the coordination frameworks. By shaping this composite into water pipes, Cs+ ions present in the contaminated water could be captured by the pipe wall. The proposed strategy will be useful, providing a potential method for fast treatment of aqueous nuclear waste

Oxidation of Alcohols into Carbonyl Compounds Using a CuO@GO Nano Catalyst in Oxygen Atmospheres

In this article, the oxidation of alcohols into carbonyl compounds was studied in oxygen atmospheres using a copper oxide on graphene oxide (CuO@GO) nano composites catalyst, synthesized by the wet chemistry method. CuO@GO nano composites were prepared from GO, and CuO NPs by the sol-gel method. The transformation of aromatic alcohols into corresponding carbonyl compounds in good-to-high yields were observed using the CuO@GO catalyst under an oxygen atmosphere. Synthesized CuO@GO was confirmed by FT-IR, XRD, XPS, TEM, FE-SEM, TEM, and SEM analyses, and revealed intercalation of CuO-NPs on/in GO nano sheets through the chelation of Cu+2 ions with CO, COOH, and OH groups presenting on the GO nano sheets. The catalytic activity of CuO@GO nano composites for the conversion of alcohols into carbonyl compounds were evaluated through TOF (2.56 × 10−3 mol g−1 min−1). The use of CuO@GO has shown catalytic activity and recyclability with a high conversion of alcohols to ketones. We assume that the proposed CuO@GO catalyst can be used for other key organic transformations and will be evaluated in the future

Synthesis of nanoporous calcium carbonate spheres using double hydrophilic block copolymer poly(acrylic acid-b-N-isopropylacrylamide)

We report self-assembly of double hydrophilic block copolymer poly(acrylic acid-b-N-isopropylacrylamide) in aqueous solution. Self-assembly of calcium ions chelated complex micelles upon mineralization reaction forms calcium carbonate (CaCO) sphere. High porosity on CaCO spheres can accommodate a large amount of anticancer drug (doxorubicin) and achieve sustainable drug release

Cr3C2 Nanoparticle-Embedded Carbon Nanofiber for Artificial Synthesis of NH3 through N-2 Fixation under Ambient Conditions

Cr3C2 Nanoparticle-Embedded Carbon Nanofiber for Artificial Synthesis of NH3 through N-2 Fixation under Ambient Condition

Electrochemical Synthesis of Ammonia Based on a Perovskite LaCrO3 Catalyst

Electrochemical synthesis of ammonia through the nitrogen reduction reaction (NRR) has the possibility to revolutionize our production of ammonia and to save our planet from both emissions and large energy consumption. In this study, a perovskite structured lanthanum chromite catalyst (LaCrO3) is synthesized, characterized as well as electrochemically evaluated for NRR. The highest ammonia yield is obtained at −0.8 V vs. reversible hydrogen electrode with an ammonia formation rate of 24.8 μg h−1 mg−1 cat, and a Faradaic efficiency of 15 %. Material calculation further confirms the possible mechanism of ammonia formation with the aid of LaCrO3 catalyst. The resulting conclusion offers a great alternative with the easily produced and low-cost perovskite structured electrocatalysts for ammonia production

Direct fabrication of tri-metallic PtPdCu tripods with branched exteriors for the oxygen reduction reaction

Design of multi-metallic nanocrystals with branched structures is very important for catalytic applications. Herein, a one-step synthesis of unique tri-metallic PtPdCu tripods with branched exteriors (PtPdCu TPs) in an aqueous solution is presented. Benefiting from their spatially and locally separated branches and tri-metallic compositions, the PtPdCu TPs exhibit superior activity and durability for the oxygen reduction reaction. The newly designed PtPdCu TPs are quite different from previous tripods in their branched exteriors. The developed one-step method is very feasible for the preparation of Pt-based multi-metallic tripods with designed compositions and desired performances

Few-layer graphitic shells networked by low temperature pyrolysis of zeolitic imidazolate frameworks

Few-layer graphitic shell networks show great promise in energy storage applications such as electrochemical accommodation of alkaline ions. However, the networking and graphitization processes remain a challenge because of the complicated procedures and high temperature used for fabrication. In this work, we report a simple synthetic method by employing low-temperature solid-state pyrolysis of ZIF-67 crystals to weave graphitic shells consisting of 3-10 layers into capsules. Owing to their unique structure, the few-layer graphitic shell networks show excellent electrochemical performance for fast sodium ion storage