The Detailed Evolution of Carbon Spheres by Hydrothermal Method

Carbon spheres (CSs) can be synthesized easily by hydrothermal method using various solutions and a lot of mechanisms have been employed to explain their formation. In our work, some special phenomena such as the uniform size and surface corruption have been found as the reaction time increased. However, less attention has been focused on the detailed evolution phenomena of CSs. In order to understand these special phenomena well, classical nucleation theory was employed to study the reaction dynamics of CSs during the evolution processes. This work not only deeply reveals the evolution mechanism of CSs, but also opens a possible way for the control of size and morphologies of CSs through hydrothermal methods

The application of localized surface plasmons resonance in Ag nanoparticles assisted Si chemical etching

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Ding, R., Dai, H., Li, M., Huang, J., Li, Y., Trevor, M., & Musselman, K. P. (2014). The application of localized surface plasmons resonance in Ag nanoparticles assisted Si chemical etching. Applied Physics Letters, 104(1), 011602 and may be found at https://doi.org/10.1063/1.4855615Localized surface plasmons excited by Ag nanoparticles are introduced in the chemical etching process of silicon. A special crateriform structure with gradually varying radius is achieved by the surface electromagnetic field enhancement effect of localized surface plasmons resonance (LSPR). Theoretical analysis demonstrates that the formation kinetics of the crateriform structures conforms to the local electromagnetic field enhancement and forward scattering induced by LSPR. The LSPR assisted photocatalytic etching offers a potential approach for the preparation of the surface microstructures used in optoelectronic devices.National Natural Science Foundation of China [91333122, 51372082, 51172069, 50972032, 61204064, 51202067]Ph.D. Programs Foundation of Ministry of Education of China [20130036110012, 20110036110006]Fundamental Research Funds for the Central Universities [11ZG02

The over-step coalescence of carbon atoms on copper surface in the CVD growth of graphene: density functional calculations

The ways in which carbon atoms coalesce over the steps on copper (111) surface are ascertained by density functional theory (DFT) calculations in the context of chemical vapor deposition (CVD) growth of graphene. Two strategies, (1) by putting carbon atoms on and under the steps separately and (2) by importing additional carbon atoms between the ones separated by the steps, have been attempted to investigate if an over-step coalescence of carbon atoms could take place. Based on analyses about the optimized configurations and adsorption energies of carbon atoms nearby the steps, as well as the energy evolution curve of the system throughout the geometry optimizations process, we determined the main way in which graphene grows over the steps continuously: the carbon atoms, adsorbed additionally on the locations between the already existing ones which are separated by the steps, link them (these carbon atoms separated by the steps) together. The direct over-step coalescence of the carbon atoms separated by the steps is very difficult, although the energy barrier preventing their coalescence can be weakened by importing carbon atoms on and under the steps gradually. Our results imply potential applications in directing the fabrication of graphene with particular structure by controlling the surface topography of copper substrate

Morphology-controlled synthesis of silver nanoparticles on the silicon substrate by a facile silver mirror reaction

The Ag nanoparticles (Ag-NPs) with different morphology were quickly deposited on p-type Si substrate by a facile silver mirror reaction without capping agents and morphology driving seeds at room temperature. By controlling the concentrations of [Ag(NH3)2]+ and reducing agent (glucose), short rod and quasi-round Ag-NPs were produced on Si substrate. The results show that the shape of the Ag-NPs was defined by [Ag(NH3)2]+ concentration. The concentration of glucose affected the coverage fraction instead of shape of Ag-NPs. Under the high concentrations of [Ag(NH3)2]+, anisotropic crystal structure of short rod Ag-NPs were ascribed to total energy minimization. The high glucose concentration led to agglomeration of particles. Different nanoporous structures on Si substrate etched by using Ag-NPs enable control over its properties and are useful for the solar cells applications