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Transition metals such as cobalt are necessary for various clean-energy technologies, notably electric-vehicle batteries. Global demand for these metals is therefore projected to increase exponentially in coming decades. Metal-ion adsorption from water offers many advantages over mining, as adsorption processes are energy-efficient and compatible with diverse water sources. Porous organic polymers are promising adsorbents: Their covalent nature provides thermal and chemical stability, while their porosity leads to high adsorption capacity. Here, we synthesized a series of amide-linked porous organic polymers denoted TMC-TAPM through the polymerization of a tri-functional acyl chloride monomer with a tetra-functional amine monomer, and we studied the resulting materials for cobalt capture from aqueous solution. By controlling monomer stoichiometry during synthesis, we obtained materials with varying amounts of carbonyl or amino groups. The materials with increasing carbonyl content showed increasing cobalt adsorption capacities, with measured adsorption capacities up to 50 mg Co g−1. Cobalt adsorption capacity was observed to plateau past a certain stoichiometric ratio, indicating an optimal monomer stoichiometry of 1.5-fold excess acyl chlorides relative to amines. The captured cobalt could be desorbed to yield a re-activated adsorbent capable of repeated adsorption cycles, without loss in performance. These results provide design rules for the synthesis of robust, high-capacity transition metal adsorbents. [ABSTRACT FROM AUTHOR]

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Controlling the formation of nanosized branched nanoparticles with high uniformity is one of the major challenges in synthesizing nanocatalysts with improved activity and stability. Using a cubic‐core hexagonal‐branch mechanism to form highly monodisperse branched nanoparticles, we vary the length of the nickel branches. Lengthening the nickel branches, with their high coverage of active facets, is shown to improve activity for electrocatalytic oxidation of 5‐hydroxymethylfurfural (HMF), as an example for biomass conversion. [ABSTRACT FROM AUTHOR]

Abstract: We present a method for the synthesis and precise size control of magnetic nanoparticles in a reversible magnetic agglomeration mechanism. In this approach, nanoparticles nucleate and grow until a critical susceptibility is reached, in which magnetic attraction overcomes dispersive forces, leading to agglomeration and precipitation. This phase change in the system arrests nanoparticle growth and gives true thermodynamic control over the size of nanoparticles. We then show that increasing the alkyl chain length of the surfactant, and hence increasing steric stabilization, allows nanoparticles to grow to larger sizes before agglomeration occurs. Therefore, simply by choosing the correct surfactant, the size and magnetic properties of iron nanoparticles can be tailored for a particular application. With the continuous addition of the precursor solution, we can repeat the steps of nucleation, growth, and magnetic agglomeration indefinitely, making the approach suitable for large scale syntheses. [ABSTRACT FROM AUTHOR]

Core-shell nanostructures are promising candidates for the next generation of catalysts due to synergistic effects which can arise from having two active species in close contact, leading to increased activity. Likewise, catalysts displaying added functionality, such as a magnetic response, can have increased scientific and industrial potential. Here, Pd/Fe3O4 core-shell nanowire clusters are synthesized and applied as hydrogenation catalysts for an industrially important hydrogenation reaction: the conversion of acetophenone to 1-phenylethanol. During synthesis, the palladium nanowires self-assemble into clusters which act as a high-surface-area framework for the growth of a magnetic iron oxide shell. This material demonstrates excellent catalytic activity due to the presence of palladium while the strong magnetic properties provided by the iron oxide shell enable facile catalyst recovery. [ABSTRACT FROM AUTHOR]

We report a new assay for breakdown of high molecular weight, insoluble lignin based on lignin films. In this method, decrease in film thickness is detected upon solubilization of mass through either chemical alteration of the lignin or molecular weight reduction. The assay was performed with organosolv lignin, the only chemical modification being an oxidative pretreatment to provide film stability with respect to dissolution. The assay is sensitive to release of as little as 20 Å of material from the film. A multiplexed format was developed using a silicone block in the form of a standard 96-well plate, allowing simultaneous assaying of a large number of reaction conditions. The assay was demonstrated using the Fenton reaction, revealing new insights into the physicochemical aspects of this reaction system with insoluble lignin. In particular, mass solubilized from the film was found to pass through a maximum as a function of the initial concentration of FeCl2 ([FeCl2]o), with the maximum occurring at [FeCl2]o = 1 mM for [H2O2]o = 5%. At that condition, solubilization of mass occurs in two stages. The reaction produces mostly ring-opened products of mass greater than 700 g mol−1, along with a minority of low molecular weight aromatics. The new insight from this work is an important step toward optimizing this complex reaction system for effective lignin breakdown. [ABSTRACT FROM AUTHOR]

This work describes a technique forforming high-density arraysand patterns of membrane-bound proteins through binding to a curvature-organizedcompositional pattern of metal-chelating lipids (Cu2+-DOIDAor Cu2+-DSIDA). In this bottom-up approach, the underlyingsupport is an e-beam formed, square lattice pattern of hemispheres.This curvature pattern sorts Cu2+-DOIDA to the 200 nm hemisphericallattice sites of a 600 nm × 600 nm unit cell in Ld- Lophase separated lipid multibilayers. Binding ofhistidine-tagged green fluorescent protein (His-GFP) creates a highdensity array of His-GFP-bound pixels localized to the square latticesites. In comparison, the negative pixel pattern is created by sortingCu2+-DSIDA in Ld- Lβ′phase separated lipid multibilayers to the flat grid between thelattice sites followed by binding to His-GFP. Lattice defects in theHis-GFP pattern lead to interesting features such as pattern circularity.We also observe defect-free arrays of His-GFP that demonstrate perfectarrays can be formed by this method suggesting the possibility ofusing this approach for the localization of various active moleculesto form protein, DNA, or optically active molecular arrays. [ABSTRACT FROM AUTHOR]