Autor(es): San-Miguel, Miguel A ; Da Silva, Edison Z ; Zanetti, Sonia M [UNESP] ; Cilense, Mario [UNESP] ; Fabbro, Maria T ; Gracia, Lourdes ; Andrés, Juan ; Longo, Elson [UNESP]
Data: 2018
Identificador Persistente: http://hdl.handle.net/11449/177995
Origem: Oasisbr
Assunto(s): Ag nanoparticles; density functional theory; plasmonic effect; transmission electron microscopy; α-Ag2WO4
Made available in DSpace on 2018-12-11T17:28:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-04-26
Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.
Institute of Chemistry State University of Campinas - Unicamp
Institute of Physics 'Gleb Wataghin' State University of Campinas - Unicamp
Institute of Chemistry UNESP (Universidade Estadual Paulista)
Chemistry Department Federal University of Sao Carlos - UFSCar
Departament de Quĩmica Fĩsica i Analĩtica Universitat Jaume i
CDMF-UNESP Universidade Estadual Paulista, PO Box 355
Institute of Chemistry UNESP (Universidade Estadual Paulista)
CDMF-UNESP Universidade Estadual Paulista, PO Box 355
