A straightforward and effective polyol route for the controllable synthesis of high-quality gold (Au) octahedra with uniform size is presented in an ethylene glycol solution. Large-scale Au octahedra with the size ranging from tens to hundreds of nanometers were selectively synthesized in high-yield. The surfaces of octahedral Au nanocrystals are smooth and correspond to {111} planes. Formation of Au nanooctahedra was attributed to the preferential adsorption of cationic surfactant poly(diallyldimethylammonium) chloride (PDDA) molecules on the {111} planes of Au nuclei that inhibited the growth rate along the <111> direction. The reduction rate of gold ions in the synthesis process can be rationally manipulated by acidic and basic solutions. This provides a facile and effective route to harvest Au octahedra with different dimensions. The synthetic strategy has the advantage of one-pot and requires no seeds, no foreign metal ions, and no pretreatment of the precursor, so that this is a practical method for controllable synthesis of Au octahedra. Size-dependent optical properties of Au octahedra were numerically and experimentally analyzed. The analysis shows that Au octahedra with sharp edges possess attractive optical properties, promising their applications to surface-enhancement spectroscopy, chemical or biological sensing, and the fabrication of nanodevices.
Superhydrophobic bionic surfaces with hierarchical micro/nano structures were synthesized by decorating single-walled or multiwalled carbon nanotubes (CNTs) on monolayer polystyrene colloidal crystals using a wet chemical self-assembly technique and subsequent surface treatment with a low surface-energy material of fluoroalkylsilane. The bionic surfaces are based on the regularly ordered colloidal crystals, and thus the surfaces have a uniform superhydrophobic property on the whole surface. Moreover, the wettability of the bionic surface can be well controlled by changing the distribution density of CNTs or the size of polystyrene microspheres. The morphologies of the synthesized bionic surfaces bear much resemblance to natural lotus leaves, and the wettability exhibited remarkable superhydrophobicity with a water contact angle of about 165 degrees and a sliding angle of 5 degrees.
A sonication-assisted sequential chemical bath deposition (S-CBD) approach is presented to uniformly decorate CdS quantum dots (QDs) on self-organized TiO2 nanotube arrays (TNTAs). This approach avoids the clogging of CdS QDs at the TiO2 nanotube mouth and promotes the deposition of CdS QDs into the nanotubes as well as on the tube walls. The photoelectrochemical and photocatalytic properties of the resulting CdS-decorated TNTAs were explored in detail. In comparison with a classical S-CBD approach, the sonication-assisted technique showed much enhancement in the photoelectrochemical and photocatalytic activities of the CdS QDs-sensitized TNTAs.
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.
We present a facile synthetic route to a silver bowl-like array film with hierarchical structures on glass substrate using the colloidal monolayer as a template. In these special hierarchical structures, microstructures were provided by a colloidal template of polystyrene latex spheres and nanostructures resulting from the thermal decomposition of silver acetate. These structures were chemically modified with 1-hexadecanethiol, and a corresponding self-assembled monolayer (SAM) was formed on their surfaces. Due to the lotus leaf-like morphology with hierarchical micro/nanostructures, the film displayed an extraordinary superhydrophobicity after chemical modification. Water contact angle and sliding angle were 169 degrees and 3 degrees (the weight of water droplets: 3 mg), respectively. Additionally, its optical property has also been investigated. This structure could be used in microfluidic devices, optical devices, and biological science.
A simple seed-layer assisted electrochemical deposition (ECD) route has been successfully developed for
preparation of different ZnO nanostructures, and their optical and field emission properties are also studied.
ZnO films, nanowires, and nanosheets could be prepared in a rational way by just controlling the ECD current
density. The corresponding growth mechanisms are also discussed on the basis of the characteristics of the
ZnO crystal structure and the influences of the seed-layer and ECD current density. Except for ZnO nanosheets,
both the room-temperature and low-temperature photoluminescence measurements of the ZnO films and
nanowire arrays show strong ultraviolet excitonic emission, which proves their good crystal quality. Detailed
analysis of the field emission (FE) properties indicates that the hierarchical ZnO nanowire array shows good
FE property due to their high aspect ratio, small radius curvature, and proper density.
A novel one-step sonochemical approach to synthesize a plasmonic photocatalyst of AgCl nanocubes (ca. 115 nm in edge length) with a small amount of Ag metal species is presented. The nanoscale Ag/AgCl hybrid photocatalysts with cubic morphology are readily formed under ambient ultrasonic conditions and neither external heat treatment nor reducing agents are required. The size of the Ag/AgCl photocatalysts could be controlled by changing the concentrations of Ag(+) ions and polyvinylpyrrolidone molecules in precursor solutions. The compositions, microstructures, influencing factors, and possible growth mechanism of the Ag/AgCl hybrid nanocubes were systematically investigated. The Ag/AgCl photocatalysts show excellent photocatalytic performance for degradation of various dye molecules under visible light.
Immer acht: Einkristalline Au‐Nanooktaeder mit genau definierter Form und einstellbarer Größe konnten mit einem modifizierten Polyolprozess hergestellt werden. Die oktaedrischen Au‐Nanokristalle haben scharfe Ecken und optische Eigenschaften, die empfindlich auf die Kristallgröße und das Abschneiden von Spitzen reagieren.
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