IN view of the interest attaching to the vaporisation and diffusion of solids, the following observations may be worthy of record.

The Diffusion of Solids

Novel properties of graphene have been well documented, whereas the importance of nanosheets of MoS2 and other chalcogenides is increasingly being recognized over the last two to three years. Borocarbonitrides, BxCyNz, with insulating BN and conducting graphene on either side are new materials whose properties have been attracting attention. These two-dimensional (2D) materials contain certain common features. Thus, graphene, MoS2, and borocarbonitrides have all been used in supercapacitor applications, oxygen reduction reactions (ORRs), and lithium-ion batteries. It is instructive, therefore, to make a comparative study of some of the important properties of these layered materials. In this article, we discuss properties related to energy devices at length. We examine the hydrogen evolution reaction facilitated by graphene, MoS2, and related materials. We also discuss gas and radiation sensors based on graphene and MoS2 as well as gas storage properties of graphene and borocarbonitrides. The article shou...

Comparative Study of Potential Applications of Graphene, MoS2, and Other Two-Dimensional Materials in Energy Devices, Sensors, and Related Areas

Plasmonic nanostructures possessing unique and versatile optoelectronic properties have been vastly investigated over the past decade. However, the full potential of plasmonic nanostructure has not yet been fully exploited, particularly with single-component homogeneous structures with monotonic properties, and the addition of new components for making multicomponent nanoparticles may lead to new-yet-unexpected or improved properties. Here we define the term "multi-component nanoparticles" as hybrid structures composed of two or more condensed nanoscale domains with distinctive material compositions, shapes, or sizes. We reviewed and discussed the designing principles and synthetic strategies to efficiently combine multiple components to form hybrid nanoparticles with a new or improved plasmonic functionality. In particular, it has been quite challenging to precisely synthesize widely diverse multicomponent plasmonic structures, limiting realization of the full potential of plasmonic heterostructures. To address this challenge, several synthetic approaches have been reported to form a variety of different multicomponent plasmonic nanoparticles, mainly based on heterogeneous nucleation, atomic replacements, adsorption on supports, and biomolecule-mediated assemblies. In addition, the unique and synergistic features of multicomponent plasmonic nanoparticles, such as combination of pristine material properties, finely tuned plasmon resonance and coupling, enhanced light-matter interactions, geometry-induced polarization, and plasmon-induced energy and charge transfer across the heterointerface, were reported. In this review, we comprehensively summarize the latest advances on state-of-art synthetic strategies, unique properties, and promising applications of multicomponent plasmonic nanoparticles. These plasmonic nanoparticles including heterostructured nanoparticles and composite nanostructures are prepared by direct synthesis and physical force- or biomolecule-mediated assembly, which hold tremendous potential for plasmon-mediated energy transfer, magnetic plasmonics, metamolecules, and nanobiotechnology.

Multicomponent Plasmonic Nanoparticles: From Heterostructured Nanoparticles to Colloidal Composite Nanostructures.

ion of hydrogen from ammonia via the high basic character of O atoms was the initial step in the surface decomposition of NH3. 200,277,278 The formed hydroxyl was also a stripping agent for NHx dehydrogenation. 277 Atomic oxygen or hydroxyl-assisted dehydrogenation steps had lower barriers than recombination reactions. As derivatives of ammonia, amines can be selectively oxidized to the associated nitriles and aldehydes dependent on oxygen coverage. For example, at low oxygen coverage (i.e., θO < 0.5ML) propylamine initially underwent N H bond breaking to produce propionitrile andwater, while the formation of propionitrile, propaldehyde, water, CO, CO2, and N2O was observed at higher oxygen coverages. 202 Weigelt et al. observed a condensation reaction via covalent interlinking between a dialdehyde and octylamine coadsorbed on Au(111) employing STM. The self-assembled structures of formed diimine were visualized, and the reaction barrier was theoretically estimated to be ∼1.2 eV. 4.7. Other Reactions Rettner and Auerbach studied the reaction dynamics of H atoms with Cl chemisorbed (via Cl2 decomposition at 400 K) on Au(111). Employing molecular beam time-of-flight methods with quantum-state-specific detection, they resolved angular and velocity distributions of the HCl product as well as its rotational and vibrational state distributions and thus revealed the concurrence of two dynamically distinct mechanisms (Eley Rideal and Langmuir Hinshelwood) during the reaction. The formed HCl via the Eley Rideal mechanism leaves the surface with a high kinetic energy in a narrow angular distribution that displays a “memory” of the direction and energy of the incident hydrogen atoms. HCl molecules produced through the Langmuir Hinshelwood mechanism have a near-thermal energy distribution and an angular distribution that is close to that of a cosine function. Outka and Madix explored the oxidation of acetylene adsorbed on oxygen-precovered (θO = 0.6 ML) Au(110). Temperatureprogrammed reaction spectroscopy (TPRS) experiments yielded water (205 K) and carbon dioxide (525 K) as reaction products. Adsorbed acetylene was dehydrogenated in the presence of oxygen to formwater, which readily desorbed. Subsequently, the carbon left behind on the surface from further reacted with atomic oxygen at higher temperatures. In a related study, no oxidation reaction occurred when ethylene was adsorbed on the same surface. Formaldehyde also reacts with atomic oxygen-covered Au(110). Oxidative products of H2O at 215 K, H2 at 230 K, and CO2, H2O, and HCOOH at 340 K were observed. 97 Another Figure 21. (a) TPD spectra from the adsorption of 0.18ML of O atoms on Au(111) at 77 K followed by 0.23 ML of NH3 at 77 K. The heating rate was 1 K/s to 400 K, then 3 K/s to 600 K. Reproduced with permission from ref 200. Copyright 2006 American Chemical Society. (b) N N recombination energy plots at two different coverages: p(2 2) and p(3 3). Yellow and blue spheres represent Au and N atoms, respectively. Relevant energies are shown in eV. Reproduced with permission from ref 277. Copyright 2006 American Chemical Society.

Structure and surface chemistry of gold-based model catalysts.

https://uwaterloo.ca/centre-advanced-materials-joining/sites/ca.centre-advanced-materials-joining/files/uploads/files/hang_growth_behaviour.pdf

Growth behavior of Cu/Al intermetallic compounds and cracks in copper ball bonds during isothermal aging.

We observed that diffuse interfaces sharpen rather than broaden in completely miscible ideal binary systems. This is shown in situ during heat treatments at gradually increasing temperatures by scattering of synchrotron radiation in coherent Mo/V multilayers containing initially diffuse interfaces. This effect provides a useful tool for the improvement of interfaces and offers a way to fabricate better x-ray or neutron mirrors, microelectronic devices, or multilayers with giant magnetic resistance.

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Transient interface sharpening in miscible alloys.

We demonstrate, using computer simulations based on deterministic kinetic equations and Monte Carlo technique, that during intermixing in an ideal AB system with an initially wide A/B interface-if the diffusion coefficient D strongly depends on concentration-the interface can become sharp on nanoscale. The sharp interface shifts proportionally with time (in contrast to the square root law). Furthermore, it is also shown that at the beginning of the intermixing in a finite bilayer or in multilayers, the diminution of the concentration gradient takes place by filling up one of the initially pure layers (layer B if D is large there) and by the shift of the sharpening interface.

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Interface Sharpening instead of Broadening by Diffusion in Ideal Binary Alloys

Size dependent spinodal decomposition in Cu-Ag nanoparticles

Possible origins of diffusional stress-free strains and their effects on interdiffusion are treated. Experimental examples of such stress effects (change of the growth rate, bending, failure of wires with coatings, stabilization of multilayers) are exposed and explained. Results of computer simulations, carried out on the basis of Stephenson’s coupled equations, are also presented. It is shown that both the “gradient” (the presence of a new term proportional to the stress gradient) and “mobility” (the pressure dependence of the diffusion coefficients) effects can be important. Special features of the above phenomena on nanometre length scale are also considered.

Diffusion-induced stresses and their relaxation

Nanoporous gold nanoparticles (NPG-NPs) with controlled particle size and pore size are fabricated via a combination of solid-state dewetting and a subsequent dealloying process. Because of the combined effects of size and porosity, the NPG-NPs exhibit greater plasmonic tunability and significantly higher local field enhancement as compared to solid NPs. The effects of the nanoscale porosity and pore size on the optical extinction are investigated for the NPG-NPs with different particle sizes experimentally and theoretically. The influences of both porosity and pore size on the plasmonic properties are very complicated and clearly different for small particles with dominated dipole mode and large particles with dominated quadrupole mode. Au/Al2O3 hybrid porous NPs with controlled porosity and composition ratio are fabricated through plasma-enhanced atomic layer deposition of Al2O3 into the porous structure. In the Au/Al2O3 hybrid porous NPs, both Au and Al2O3 components are bicontinuously percolated over ...

Zoltán Erdélyi

Papers

Transient interface sharpening in miscible alloys.

Interface Sharpening instead of Broadening by Diffusion in Ideal Binary Alloys

Size dependent spinodal decomposition in Cu-Ag nanoparticles

Diffusion-induced stresses and their relaxation

Nanoporous Gold Nanoparticles and Au/Al2O3 Hybrid Nanoparticles with Large Tunability of Plasmonic Properties