Colloidal synthesis of Pt–In bimetallic nanoparticles for propane dehydrogenation

Recently, Pt-based bimetallic nanoparticles have drawn much attention because of their great catalytic performance and wide applications in diverse fields. In this work, we report that bimetallic Pt–In nanoparticles with uniform size distribution and controllable composition can be synthesized through a one-step, facile colloidal approach. Various characterization tools such as XRD, TEM, XPS, and synchrotron techniques have been used to characterize the as-obtained nanoparticles. It is demonstrated that the Pt and In elements are homogeneously distributed in the whole nanoparticle. The bimetallic Pt–In nanoparticles have shown great catalytic performance, including high activity, high selectivity, and high stability, for the propane dehydrogenation reaction to produce propene, one of the most important chemicals. The excellent catalytic performance makes Pt–In bimetallic nanoparticles promising catalysts in future industrial application.

Ultrathin ZnSe nanowires: one-pot synthesis via a heat-triggered precursor slow releasing route, controllable Mn doping and application in UV and near-visible light detection

We report herein a heat-triggered precursor slow releasing route for the one-pot synthesis of ultrathin ZnSe nanowires (NWs), which relies on the gradual dissolving of Se powder into oleylamine containing a soluble Zn precursor under heating. This route allows the reaction system to maintain a high monomer concentration throughout the entire reaction process, thus enabling the generation of ZnSe NWs with diameter down to 2.1 nm and length approaching 400 nm. The size-dependent optical properties and band-edge energy levels of the ZnSe NWs were then explored in depth by UV-visible spectroscopy and cyclic voltammetry, respectively. Considering their unique absorption properties, these NWs were specially utilized for fabricating photoelectrochemical-type photodetectors (PDs). Impressively, the PDs based on the ZnSe NWs with diameters of 2.1 and 4.5 nm exhibited excellent responses to UVA and near-visible light, respectively: both possessed ultrahigh on/off ratios (5150 for UVA and 4213 for near-visible light) and ultrawide linear response ranges (from 2.0 to 9000 μW cm^-2 for UVA and 5.0 to 8000 μW cm^-2 for near-visible light). Furthermore, these ZnSe NWs were selectively doped with various amounts of Mn²⁺ to tune their emission properties. As a result, ZnSe NW film-based photochromic cards were creatively developed for visually detecting UVA and near-visible radiation.

Real-time visualization of diffusion-controlled nanowire growth in solution

This Letter shows that copper nanowires grow through the diffusion-controlled reduction of dihydroxycopper(I), Cu(OH)2(-). A combination of potentiostatic coulometry, UV-visible spectroscopy, and thermodynamic calculations was used to determine the species adding to growing Cu nanowires is Cu(OH)2(-). Cyclic voltammetry was then used to measure the diffusion coefficient of Cu(OH)2(-) in the reaction solution. Given the diameter of a Cu nanowire and the diffusion coefficient of Cu(OH)2(-), we calculated the dependence of the diffusion-limited growth rate on the concentration of copper ions to be 26 nm s(-1) mM(-1). Independent measurements of the nanowire growth rate with dark-field optical microscopy yielded 24 nm s(-1) mM(-1) for the growth rate dependence on the concentration of copper. Dependence of the nanowire growth rate on temperature yielded a low activation energy of 11.5 kJ mol(-1), consistent with diffusion-limited growth.

New Gold Nanostructures for Sensor Applications: A Review

Gold based structures such as nanoparticles (NPs) and nanowires (NWs) have widely been used as building blocks for sensing devices in chemistry and biochemistry fields because of their unusual optical, electrical and mechanical properties. This article gives a detailed review of the new properties and fabrication methods for gold nanostructures, especially gold nanowires (GNWs), and recent developments for their use in optical and electrochemical sensing tools, such as surface enhanced Raman spectroscopy (SERS).

Ultrathin nanostructures: smaller size with new phenomena

Ultrathin nanostructures possess the very essential features of nanomaterials, including quantum-confinement effects and unconventional reactivities, which are determined by the significant structure variations from the bulk material. More and more isolated reports on ultrathin nanostructures and various new phenomena have appeared in recent years but a comprehensive review on their typical features and future development has not followed. Here we aim to present a well-organized review which comments on the most important characteristics of non-carbon ultrathin nanostructures, in an attemp to reveal the underlying relationship between their reactivity, stability and transformation law, and their structures.

Nanowires and nanostructures that grow like polymer molecules

Unique properties (e.g., rubber elasticity, viscoelasticity, folding, reptation) determine the utility of polymer molecules and derive from their morphology (i.e., one-dimensional connectivity and large aspect ratios) and flexibility. Crystals do not display similar properties because they have smaller aspect ratios, they are rigid, and they are often too large and heavy to be colloidally stable. We argue, with the support of recent experimental studies, that these limitations are not fundamental and that they might be overcome by growth processes that mimic polymerization. Furthermore, we (i) discuss the similarities between crystallization and polymerization, (ii) critically review the existing experimental evidence of polymer-like growth kinetic and behavior in crystals and nanostructures, and (iii) propose heuristic guidelines for the synthesis of "polymer-like" crystals and assemblies. Understanding these anisotropic materials at the boundary between molecules and solids will determine whether we can confer the unique properties of polymer molecules to crystals, expanding them with topology, dynamics, and information and not just tuning them with size.