Tailored nanoparticles: Uniform Pd icosahedra (see TEM images) were controllably synthesized in high yield by a facile polyol process. Their size can be readily tailored from 15 to 42 nm by tuning ...the reaction parameters. The high density of twin boundaries and sharp edges on the surfaces of the Pd icosahedra could make them promising for many applications, for example, catalysis.
A facile and low-cost method to prepare periodic Au@metal-organic framework （MOF） （MIL-100（Fe）） nanoparticle arrays was developed. The arrays were fabricated in situ using monolayer colloidal ...crystals as templates, followed by Au deposition on substrates, and annealing. MIL-100（Fe） coatings were applied on the nanospheres using a simple solvent thermal process. The prepared periodic Au@MIL-100（Fe） nanoparticle （NP） arrays were characterized by two peaks in the visible spectra. The first peak represented the surface plasmon resonance （SPR） of the Au nanospheres, and the other peak, or the diffraction peak originated from the periodic structure in the NP array. After modification with 3-aminophenylboronic acid hemisulfate （PBA）, the Au@MIL-100（Fe） NP arrays exhibited sensitive responses to different glucose concentrations with good selectivity. These responses could be due to the strong interaction between PBA and glucose molecules. The diffraction peak was sensitive at low glucose concentrations （less than 12 mM）, whereas the SPR peak rapidly responded at high concentrations. The peaks thus demonstrated satisfactory complementary sensitivity for glucose detection in different concentration regions. These results can be used to develop a dual-channel biosensor. We also created a standard diagram, which can be used to efficiently monitor blood glucose levels. The proposed strategy can be extended to develop different dual-channel sensors using Au@MIL-100（Fe） NP arrays agents. functionalized with different recognition
We apply a nanomanipulation technique to assemble pairs of monodispersed octahedral gold nanocrystals (side length, 150 nm) along their major axes with a varying tip-to-tip separation (25−125 nm). ...These pairs are immobilized onto indium tin oxide coated silica substrates and studied as plasmonic dimers by polarization-selective total internal reflection (TIR) microscopy and spectroscopy. We confirm that the plasmon coupling modes with the scattering polarization along the incident light direction result from the transverse-magnetic-polarized incident light, which induces two near-field-coupled dipole moments oriented normal to the air−substrate interface. In such cases, both in-phase (antibonding) and antiphase (bonding) plasmon coupling modes can be directly observed with the incident light wave vector perpendicular and parallel to the dimer axis, respectively. The observation of antiphase plasmon coupling modes (“dark” plasmons) is made possible by the unique polarization nature of the TIR-generated evanescent field. Furthermore, with decreasing nanocrystal separation, the plasmon coupling modes shift to shorter wavelengths for the incident light perpendicular to the dimer axis, whereas relatively large red shifts of the plasmonic coupling modes are found for the parallel incident light.
A capillary gradient‐induced self‐assembly strategy is developed to successfully fabricate 2D periodic Au nanosphere arrays on a centimeter‐sized scale through a bisolvent system at air/water ...interface. The bisolvent system used in this strategy consists of two steps. It first induces Au nanoparticles (NPs) floating on the water surface. Then, it compresses the sparse Au NPs into a densely close‐packed array by creating an effective capillary gradient along the water surface. This study indicates that the effects of the capillary gradient depend on water solubility and vapor pressure of a compressing solvent. A compression mechanism of capillary gradient is reasonably proposed for such self‐assembly of a densely packed monolayer on the water surface. This proposed self‐assembly strategy has advantages of having a simple operation and being environment‐friendly. The assembled Au NP arrays can provide an important and promising platform for major applications in biosensors and catalysis.
A capillary gradient‐induced self‐assembly strategy to organize monodispersed Au nanospheres into periodic dense 2D Au nanosphere arrays over a centimeter‐sized scale at the air/water interface is presented by using a bisolvent system. The presented strategy has advantages of having a simple operation and being environment‐friendly.
Using clean solar energy to reduce CO2 into value-added products not only consumes the over-emitted CO2 that causes environmental problems, but also generates fuel chemicals to alleviate energy ...crises. The photocatalytic CO2 reduction reaction (PCO2RR) relies on the semiconductor photocatalysts that suffer from high recombination rate of the photo-generated carriers, low light harvesting capability, and low stability. This review explores the recent discoveries on the novel semiconductors for PCO2RR, focusing on the rational catalyst design strategies (such as surface engineering, band engineering, hierarchical structure construction, single-atom catalysts, and biohybrid catalysts) that promote the catalytic performance of semiconductor catalysts on PCO2RR. The advanced characterization techniques that contribute to understanding the intrinsic properties of the photocatalysts are also discussed. Lastly, the perspectives on future challenges and possible solutions for PCO2RR are presented.
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Pieces of eight: Single‐crystalline Au nano‐octahedra with well‐defined shape and tunable size can be synthesized by a modified polyol process. The octahedral Au nanocrystals have sharp corners and ...display optical properties that are sensitive to the crystal sizes and the truncation of the tips.
•BiOCl0.9I0.1/BiON catalysts are reasonably designed and synthesized via a room temperature in-situ etching method.•BiOCl0.9I0.1/BiON catalysts provide typical sample model to study heterojunction ...effect for the photodegradation of tetracycline.•Enhanced photodegradation activity due to photogenerated carriers separation and specific surface area optimized by heterojunction design.
Hierarchical heterostructures have emerged as promising candidates for the efficient photocatalytic degradation of antibiotics owing to their matched energy levels and tunable absorption bands. Herein, we report the facile synthesis of a heterojunction photocatalyst composed of basic bismuth nitrate (BiON) and BiOCl0.9I0.1 using a simple room-temperature hydrolysis method. Our results demonstrate that the BiON/BiOCl0.9I0.1 composite exhibits superior photodegradation performance compared to pure-phase materials owing to the catalytic enhancement at the heterointerface and the effective separation of the photogenerated carriers. Moreover, the unique three-dimensional microsphere morphology of the synthesized composite enhances its specific surface area and light absorption, further enhancing its photocatalytic activity. In the tetracycline (TC) photodegradation reaction as a model reaction, the catalyst could degrade 88% of TC in just 25 min. Overall, this work provides a promising strategy for the facile and low-cost synthesis of heterogeneous photocatalytic degradation materials.
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In this study, an effective wet-chemical route was developed in an aqueous solution for the synthesis of spindle-like palladium nanoparticles(Pd NPs). Spindle-like Pd NPs in high-yield were ...successfully synthesized by using cetyltrimethylammonium chloride(CTAC) as surfactant and ascorbic acid(AA) as reduction reagent. The influence factors including the concentration of CTAC, AA, and Na I, as well as the reaction temperature for synthesis of spindle-like Pd NPs were systematically investigated. The formation mechanism of spindle-like Pd NPs was proposed on the basis of these experimental results. Spindlelike Pd NPs with high density of twins and sharp edges exhibit enhanced catalytic activities for the reduction of 4-nitrophenol.
As substitutes for natural peroxidases, most nanomaterial-based enzyme mimetics (nanozymes) have unique properties such as high stability, low-cost, large surface area, and high catalytic activity. ...However, they usually work in acidic conditions and thus impede their real applications. In this work, by modulating the nanostructure, composition, and surface property of the bimetallic materials, the positively charged poly(diallyldimethylammonium)-stabilized Au@Ag heterogeneous nanorods (NRs) were developed as synergistic peroxidase-like interfaces, which exhibited high activity over a wide pH range (pH 4.0–6.5) using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the chromogenic substrate. At pH 6.5, the peroxidase-like activity for the Au@Ag heterogeneous NRs was stable and optimal within 20–40 °C. Moreover, the Au@Ag heterogeneous NRs showed excellent temperature stability and long-term storage stability. Given these characters, the detection of H2O2 at pH 6.5 was proposed on the basis of the Au@Ag heterogeneous NRs catalyzing the colorimetric reaction of H2O2 and ABTS, where the oxidized ABTS showed a typical absorption peak at 414 nm. The absorbance at 414 nm was linear with H2O2 concentration from 0.01 to 10 mM. Further, considering that Au@Ag heterogeneous NRs and glucose oxidase (GOx) have similar optimal pH for catalytic activities, a novel one-pot method for the detection of glucose was developed by the coupled catalytic reaction using GOx, Au@Ag heterogeneous NRs, and ABTS at nearly neutral pH (pH 6.5) and 37 °C. This proposed method had simple and rapid processes, wide linear range (0.05–20 mM), and reliability for the successful analysis of real samples. On the basis of these attractive and unique characteristics, Au@Ag heterogeneous NRs can become promising substitutes for peroxidase in analytical chemistry and environmental science.
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