The Mo2C@C catalyst was prepared by the calcination method under the argon gas flow of the activated walnut shell-ammonium heptamolybdate hybrid powder mixture, enhancing the electrocatalytic ...hydrogen evolution process.
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•The waste walnut shell powder was chosen as the carbon source for HER catalysts.•The walnut shell powders derived carbon matrix can enhance the electron transfer.•The open pores can facilitate electrolyte permeation and hydrogen release.
Herein, we choose the waste walnut shell as the carbon source, and ammonium heptamolybdate as the molybdenum source to prepare the β-Mo2C catalyst supported on carbon matrix (Mo2C@C) by the calcination method for hydrogen evolution reaction (HER). The open pores in the porous Mo2C nanoparticle clusters can facilitate electrolyte permeation and hydrogen molecules release as well as the carbon matrix can enhance the conductivity. As a result, the optimal Mo2C exhibits an efficient HER performance, with an overpotential of 140 mV at 10 mA cm−2 and a Tafel slope of 63 mV dec−1 as well as excellent electrochemical stability. The strategy changing waste walnut shell into the effective catalysts sets an example for the searching and designing rational energy materials.
Three-dimensional (3D) reduced graphene oxide (rGO) anchored carbon-coated Fe2O3 core-shell nanoparticles (Fe2O3@C-rGO) has been developed successfully through a simple one-pot hydrothermal process ...followed by a further annealing treatment. The 3D Fe2O3@C-rGO nanocomposite consists of carbon-coated Fe2O3 nanoparticle clusters (Fe2O3@C) and rGO nanosheets. The homogenously distributed and intercalated Fe2O3@C nanoparticles between rGO nanosheets form a highly conductive 3D carbon network with rGO, and present a hierarchical pore size structure, enabling fast ion and electron transport, as well as remarkable specific surface area. The electrochemical performance in supercapacitor has been characterized, and the as-prepared Fe2O3@C-rGO electrode shows a significant high specific capacitance of 211.4 F/g at 0.5 A/g and 177.2 F/g at 20 A/g with no visible performance decay even after 2500 cycles testing. These properties indicate a good potential to achieve high performance electrochemical devices.
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•The Fe2O3@C-rGO electrode showed 3D intercalated structure.•The 3D Fe2O3@C-rGO was prepared by hydrothermal method in one-step.•A synergistic effect of the Fe2O3, rGO and the interconnected carbon nanosphere has been studied.•The 3D Fe2O3@C-rGO electrode showed excellent capacitive performances.•The synthesis method is general and simple.
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•Fe3O4 nanoparticle clusters with enhanced magnetic properties were prepared successfully by ACMF-assisted co-precipitation.•The magnetic effect as well as heat effect of ACMF on ...Fe3O4 nanoparticles plays a key role in the enhancement of magnetic properties during the whole synthesis process.•This strategy might hold promise in preparation of high performance magnetic nanomaterials in the future.
Field-assisted synthesis has been one of the common strategies of nanoparticles preparation with enhanced properties. However, most researches focused on exploring the effects of monofunctional static field on the structure and properties of synthetic nanomaterials, few researchers have applied fields with period variation as assistance. Combining medium alternating current magnetic field with most widely used method traditional chemical co-precipitation held potential in preparation high quality Fe3O4 nanoparticle. In this study, Fe3O4 nanoparticle clusters were prepared in alternating-current magnetic field (ACMF) by co-precipitation principle, structural and magnetic properties were also characterized. Results demonstrated that Fe3O4 nanoparticle clusters prepared by co-precipitation heated in ACMF indicated a better heat production under ACMF, comparing with Fe3O4 nanoparticle clusters with similar size and distribution prepared by classic co-precipitation. It might be due to the magnetic effects induced by ACMF that Fe3O4 nanoparticles tend to grow along the magnetization direction. This technology might hold promise in preparation high performance magnetic nanomaterial in the future.
Antibacterial efficiency can be effectively improved by applying targeting antibacterial materials and strategies. Herein, the successful synthesis of uniform pH‐responsive Ag nanoparticle clusters ...(AgNCs) is demonstrated, which can collapse and reassemble into nonuniform Ag NPs upon exposure to the acidic microenvironment of bacterial infections. This pH triggered reassembly contributes greatly to the improved antibacterial activities of AgNCs against both methicillin‐resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The minimum inhibitory concentration and minimum bactericidal concentration against MRSA are as low as 4 and 32 µg mL−1 (which are 8 and 32 µg mL−1 for E. coli), respectively. In vivo skin wound healing experiments confirm AgNCs can serve as an effective wound dressing to accelerate the healing of MRSA infection. The development of responsive AgNCs offers new materials and strategies in targeting antibacterial applications.
The designed Ag nanoparticles clusters can undergo a collapse and reassembly process upon exposure to the acidic microenvironment of bacterial infections, which results in the highly efficient targeting antibacterial ability.
Exosomes are a class of naturally occurring nanoparticles that are secreted endogenously by mammalian cells. Clinical applications for exosomes remain a challenge because of their unsuitable donors, ...low scalability, and insufficient targeting ability. In this study, we developed a dual-functional exosome-based superparamagnetic nanoparticle cluster as a targeted drug delivery vehicle for cancer therapy. The resulting exosome-based drug delivery vehicle exhibits superparamagnetic behavior at room temperature, with a stronger response to an external magnetic field than individual superparamagnetic nanoparticles. These properties enable exosomes to be separated from the blood and to target diseased cells. In vivo studies using murine hepatoma 22 subcutaneous cancer cells showed that drug-loaded exosome-based vehicle delivery enhanced cancer targeting under an external magnetic field and suppressed tumor growth. Our developments overcome major barriers to the utility of exosomes for cancer application.
Abstract In this study, the photothermal effect of magnetic nanoparticle clusters was firstly reported for the photothermal ablation of tumors both in vitro in cellular systems but also in vivo ...study. Compared with individual magnetic Fe3 O4 nanoparticles (NPs), clustered Fe3 O4 NPs can result in a significant increase in the near-infrared (NIR) absorption. Upon NIR irradiation at 808 nm, clustered Fe3 O4 NPs inducing higher temperature were more cytotoxic against A549 cells than individual Fe3 O4 NPs. We then performed in vivo photothermal therapy (PTT) studies and observed a promising tumor treatment. Compared with PBS and individual magnetic Fe3 O4 NPs by NIR irradiation, the clustered Fe3 O4 NPs treatment showed a higher therapeutic efficacy. The treatment effects of clustered Fe3 O4 NPs with different time of NIR illumination were also evaluated. The result indicated that a sustained high temperature generated by NIR laser with long irradiation time was more effective in killing tumor cells. Furthermore, histological analysis of H&E staining and TUNEL immunohistological assay were further employed for antitumor efficacy assessment of PTT against A549 tumors.
Resin composites have been frequently applied in dental restoration due to their distinguished overall performance. The size, structure and composition of inorganic fillers have significant effects ...on the properties of dental resin composites (DRCs). The aim of our research is to strengthen the structure of spray-dried silica colloidal nanoparticle clusters (SCNCs) by means of a calcination process, and achieve the excellent comprehensive performance of DRCs by the combined use with different fillers. The results indicate that the SCNCs calcined at 500 °C has a significant strengthening effect on the flexural properties and hardness of DRCs except the decrease of compressive strength in comparison to the uncalcined SCNCs. To overcome this problem, the SiO2 nanoparticles (NPs) as building blocks for SCNCs and the SCNCs were further adopted as co-fillers of the calcined SCNCs (CSCNCs). It can be found that the strengthening effect of SCNCs is better than that of the NPs at the same filling ratio. The DRCs filled with 60 wt% CSCNCs and 10 wt% SCNCs have a greatly enhanced compressive strength, reaching the same level with the DRCs filled with 70 wt% SCNCs. More importantly, the corresponding flexural strength (143.5 ± 8.3 MPa), flexural modulus (8.91 ± 0.48 GPa) and hardness (70.7 ± 1.4 HV) still have an improvement of 14%, 23% and 48% in comparison with those of the counterpart, respectively.
•Realizing architectural engineering of CNCs with quite different nanocrystal subunit.•Plenty of grain boundary and lattice distortion are formed within PtNi/CeO2 CNCs.•The unique CNC structure ...improves the electron conductivity of PtNi/CeO2.•These novel functions contribute to the efficient electrooxidation of liquid fuels.
Clustering pony-size nanocrystals into secondary structures (colloidal nanocrystal clusters, CNCs) not only combines the properties of primary nanocrystals, but also obtains the novel functions originated from the strengthened interactions between neighboring nanocrystals. Herein, we use the PtNi clusters and CeO2 clusters as the primary subunits to construct the PtNi/CeO2 CNCs, which can enhance the interaction between PtNi and CeO2 clusters, as well as improve the electron conductivity of CeO2 originated from the strengthened attachment. Plenty of grain boundaries and lattice distortion generated after introducing the CeO2 clusters into the inner surface of PtNi CNCs, which improves the electrooxidation activity and anti-CO-poisoning ability of PtNi/CeO2 CNCs. Specifically, the PtNi/CeO2 CNCs exhibited higher specific activities than PtNi CNCs towards electrooxidation reactions of methanol, formic acid and ethylene glycol, as well as 8.5, 7.7 and 7.0 times higher than those of Pt/C, respectively, along with enhanced stability. Combined with the experiments and characterizations, the improved property is originated from the novel functions of grain boundary, subtle lattice distortion and strengthened interaction. This study realizes architectural engineering of CNCs with quite different nanocrystal subunits, and creates an effective strategy for eliminating the disadvantages of conventional Pt/CeO2 catalyst in electrooxidation of liquid fuels.
Hydrophobic interactions constitute one of the most important types of nonspecific interactions in biological systems, which emerge when water molecules rearrange as two hydrophobic species come ...close to each other. The prediction of hydrophobic interactions at the level of nanoparticles (Brownian objects) remains challenging because of uncontrolled diffusive motion of the particles. We describe here a general methodology for solvent-induced, reversible self-assembly of gold nanoparticles into 3D clusters with well-controlled sizes. A theoretical description of the process confirmed that hydrophobic interactions are the main driving force behind nanoparticle aggregation.
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.
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