Carbon mineralization—converting carbon dioxide (CO2) into stable carbonate minerals, such as calcium carbonate (CaCO3)—has attracted much attention as a permanent way to sequester CO2. In this ...study, we developed a novel method for improving the efficiency of carbon mineralization using amine-functionalized magnetic nanoparticle clusters (A-MNCs). To prepare them, magnetic nanoparticle clusters composed of tens of small Fe3O4 nanoparticles were treated with 3-aminopropyltriethoxysilane to functionalize amine groups on their surfaces. When CO2 was bubbled into a NaOH solution, the rate of CO2 dissolution was enhanced in the presence of A-MNCs, mostly due to physical effects such as grazing and hydrodynamic effects that improved mass transfer between the solution and CO2 bubbles. In addition, A-MNCs promoted carbon mineralization in a NaOH solution containing Ca2+ by providing an additional mineralization route via carbamate formation, resulting in a threefold increase in efficiency to 81 %. We demonstrated that A-MNCs could be applied to leachate from slag, a byproduct of commercial steelmaking, increasing the efficiency by 2.6 times compared to the absence of A-MNCs. The resulting CaCO3 precipitate was confirmed to be calcite using X-ray diffraction and scanning electron microscopy. Furthermore, after the mineralization, A-MNCs were easily separated from the solution using a permanent magnet, while retaining their performance.
•A-MNCs improved CO2 dissolution rate by increasing mass transfer between the solution and CO2.•A-MNCs enhanced the carbon mineralization efficiency from 28 % to 81 %.•When A-MNCs were used in slag leachate, the mineralization efficiency reached 85 %.•The magnetically separated A-MNCs retained nearly consistent performance.
Granular materials, composed of densely packed particles, are known to possess unique mechanical properties that are highly dependent on the surface structure of the particles. A microscopic ...understanding of the structure‐property relationship in these systems remains unclear. Here, supra‐nanoparticle clusters (SNPCs) with precise structures are developed as model systems to elucidate the unexpected elastic behaviors. SNPCs are prepared by coordination‐driven assembly of polyhedral oligomeric silsesquioxane (POSS) with metal‐organic polyhedron (MOP). Due to the disparity in sizes, the POSS‐MOP assemblies, like their classic nanoparticles counterparts, ordering is suppressed, and the POSS‐MOP mixtures will vitrify or jam as a function of decreasing temperature. An unexpected elasticity is observed for the SNPC assemblies with a high modulus that is maintained at temperatures far beyond the glass transition temperature. From studies on the dynamics of the hierarchical structures of SNPCs and molecular dynamic simulation, the elasticity has its origins in the interpenetration of POSS‐ended arms. The physical molecular interpenetration and inter‐locking phenomenon favors the convenient solution or pressing processing of the novel cluster‐based elastomers.
Supra‐nanoparticle clusters (SNPCs) were synthesized by convergence of metal–organic polyhedron scaffolds with precise giant building blocks. The mechanical properties and structural dynamics can be regulated by fine‐tuning the surface functionalization of the terminal POSS moieties. Unexpected elasticity with high Young's modulus of the OPOSS‐ended SNPCs was found to be highly correlated with the interpenetration of the neighboring GLs.
We demonstrate template-guided self-assembly of gold nanoparticles into ordered arrays of uniform clusters suitable for high-performance SERS on both flat (silicon or glass) chips and an optical ...fiber faucet. Cluster formation is driven by electrostatic self-assembly of anionic citrate-stabilized gold nanoparticles (∼11.6 nm diameter) onto two-dimensionally ordered polyelectrolyte templates realized by self-assembly of polystyrene-block-poly(2-vinylpyridine). A systematic variation is demonstrated for the number of particles (N ≈ 5, 8, 13, or 18) per cluster as well as intercluster separations (S c ≈ 37–10 nm). Minimum interparticle separations of <5 nm, intercluster separations of ∼10 nm, and nanoparticle densities on surfaces as high as ∼7 × 1011/in.2 are demonstrated. Geometric modeling is used to support experimental data toward estimation of interparticle and intercluster separations in cluster arrays. Optical modeling and simulations using the finite difference time domain method are used to establish the influence of cluster size, shape, and intercluster separations on the optical properties of the cluster arrays in relation to their SERS performance. Excellent SERS performance, as evidenced by a high enhancement factor, >108 on flat chips and >107 for remote sensing, using SERS-enabled optical fibers is demonstrated. The best performing cluster arrays in both cases are achievable without the use of any expensive equipment or clean room processing. The demonstrated approach paves the way to significantly low-cost and high-throughput production of sensor chips or 3D-configured surfaces for remote sensing applications.
In article number 1701633, Sang Woo Han and co‐workers report a new synthetic strategy for the formation of colloidal clusters of core‐shell nanoparticles consisting of plasmonic Au cores and ...catalytically active shells with a high density of sub‐1 nm interparticle gaps. The prepared nanoparticle clusters realize the synergistic integration of plasmonic and catalytic functions in a single platform.
A novel enzyme-free glucose sensor is developed with the three-dimensional (3D) PtxNi1-x (x=0.1–0.9) alloy nanoclusters electrodeposited onto multi-walled carbon nanotubes (MWCNTs). The synthesis, ...structural, and compositional characterization of 3D PtxNi1-x/MWCNTs are reported. Cyclic voltammetry, linear sweep voltammetry, kinetic analysis, electrochemical impedance plots, and amperometric responses exhibit that the 3D PtxNi1-x/MWCNTs nanocomposites have more remarkable catalytic performance on the direct oxidation of glucose comparing with the 3D Pt/MWCNTs catalysts and the uniform dispersive morphology PtxNi1-x/MWCNTs catalysts. We further investigate how the Pt/Ni atomic ratios of these alloys play a key role in controlling the electrocatalytic activity and thus improve the glucose detection. The optimal Pt/Ni atomic ratio acquired in present experiment condition is 3/7, which proves linearity up to 15mM of glucose with a sensitivity of 0.94mA/mMcm2 and a detection limit of 0.3μM (S/N=3) at −0.30V. Meanwhile, the interference from dopamine, uric acid, p-acetamidophenol, ascorbic acid, urea, galactose, lactose and fructose is effectively avoided at this negative potential. The as-synthesized sensor is applicable to the glucose sensing in the real human serum with the concentrations agreeing well with that measured by a hospital. Furthermore, 90% of the surface active sites and the initial sensitivity are retained in continuous tests (31 days), proving favorable long-term stability.
Assemblies of magnetite nanoparticles created by the ultrasonic mechanocavitation in a viscous liquid have been obtained for use in magnetic hyperthermia. The magnetite nanoparticles inherit the ...perfect crystal structure of the original coarse-grained magnetite powder, with characteristic sizes of 0.2–8 μm, and have a high saturation magnetization, Ms = 92 emu/g, close to the value of pure magnetite. Measurements of the specific absorption rate (SAR) of assemblies in an alternating (ac) magnetic field showed a significant dependence of SAR on the nanoparticle concentration, as well as on the shape of particle macroaggregates. A 4-fold increase in the SAR of elongated clusters of particles oriented parallel to the action of ac magnetic field was found in comparison with an assembly of quasi-spherical clusters. In addition a sharp dependence of the SAR of an assembly of elongated clusters on the ac magnetic field direction with respect to the cluster orientation axis was revealed. The results obtained are in qualitative agreement with the results of numerical simulation of dense clusters of magnetic nanoparticles based on the solution of the stochastic Landau-Lifshitz equation.
A noble metal-free Na Al Si doped libethenite nanoparticle clusters were obtained by applying the method of hydrothermal synthesis. The Linear Sweep Voltammetry (LSV) curve of this nanoparticle ...cluster electrode shows that there is no noble metal in the hydrogen evolution reaction (HER), and it still exhibits good catalytic activity. The catalytic activity of the libethenite nanoparticle cluster is further enhanced after reduction by the amperometric i-t curve method (A i-t C). The electrochemical performance and catalytic mechanism were investigated by the cyclic voltammetry (CV) method. The characterization analysis by XRD, SEM, TEM, EDS, and XPS found that the catalyst was isomorphous with the natural mineral libethenite, but different from the minerals with Cu and P as the main components in nature when the crystal synthesized under hydrothermal conditions was doped. The heterogenous libethenite nanoparticle cluster framework is replaced by more additional Na, Al, and Si elements. Cu and P elements in the libethenite nanoparticle cluster structure are connected through the mineral framework and uniformly distributed in the crystal structure. This structure increases the electrochemical activity of its HER. Due to the interaction of Cu and P, the catalyst exhibits good catalytic performance for HER under acidic conditions. The reduction by the electrochemical i-t curve reduces the consumption of Cu and enhances the stability of the mineral framework.
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•An inorganic doped libethenite nanoparticle clusters catalyst exhibited high activity in the HER.•Electrochemical reduction method is used to improve catalytic performance.•High activity catalyst in HER for high energy density cell.•Low cost and environment protection for none noble metal.
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•Mobile gold nanoparticle clusters encapsulated into hollow silica spheres.•The hollow spheres assembled in a specific space by external electric fields.•Reversible control over the ...assembled and dispersed states of the hollow spheres.•Raman intensities depending on the assembled states of the hollow spheres.•The hollow spheres providing compartments to keep the clusters colloidally stable.
Assembly of plasmonic nanoparticle clusters having hotspots in a specific space is an effective way to efficiently utilize their plasmonic properties. In the assembly, however, bulk-like aggregates of the nanoparticles are readily formed by strong van der Waals forces, inducing a decrease of the properties. The present work proposes an advanced method to avoid aggregation of the clusters by encapsulating into a confined space of hollow silica interior. Hollow spheres incorporating gold nanoparticle clusters were synthesized by a surface-protected etching process. The observation of inner nanoparticles with liquid cell transmission electron microscopy experimentally proved that the nanoparticles moved as a cluster instead of as dispersed nanoparticles within the water-filled hollow compartment. The hollow spheres incorporating the nanoparticle clusters were assembled in the vicinity of electrodes by application of an external AC electric field, resulting in the enhancement of Raman intensities of probe molecules. The nanoparticle-cluster-containing hollow spheres were redispersed when the electric field was turned off, showing that the hollow silica spheres can act as a physical barrier to avoid the cluster aggregation. The Raman intensities were reversibly changed by switching the electric field on and off to control the assembled or dispersed states of the hollow spheres.
Nanobubbles have been widely studied for their use in water treatments. Conventional methods for producing nanobubbles require significantly high levels of electric power. A system that involves ...inducing an alternative magnetic field (AMF) in flowing water has been developed, which has relatively low power requirements compared to other methods. Experimental results are presented that indicate nanobubbles are generated by this AMF system. These results include ζ potential measurements in deionized water, light scattering observations, and nanoparticle tracking analysis (NTA) measurements of object size and relative scattering intensity for water containing 5 × 10–4 M CaCO3. The NTA results also suggest the formation of nanobubble–nanoparticle clusters. Finally, an earlier work is reviewed which demonstrated that this AMF treatment led to the removal of tubercles on the inner walls of pipe samples. This prior result is discussed in light of the present evidence of nanobubble formation and a hypothesis is proposed based on the dissolution of CaCO3 as a result of nanobubble–nanoparticle clustering.
Manipulation of nanomaterials such as nanoparticles (NPs) and nanorods (NRs) to make clusters is of significant interest in material science and nanotechnology due to the unusual collective ...opto-electric properties in such structures that cannot be found in the individual NPs. This work demonstrates an effective way to arrange NP clusters (NPCs) to make the desired arrays based on removable and NP-guidable liquid crystalline template using sublimation and reconstruction phenomenon. The position of the NPCs is precisely controlled by the defect structure of the liquid crystal (LC), namely toric focal conic domains (TFCDs), during thermal annealing to construct the LC and corresponding NPC structures. As a proof of concept, the surface-enhanced Raman scattering (SERS) activity of a fabricated array of gold nanorod (GNR) clusters is measured and shown to have highly sensitive detection characteristics essential for potential sensing applications.
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