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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

On the Effect of Native SiO2 on Si over the SPR-mediated Photocatalytic Activities of Au and Ag Nanoparticles

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Autor(es):
Wang, Jiale ; de Freitas, Isabel C. ; Alves, Tiago V. ; Ando, Romulo A. ; Fang, Zebo ; Camargo, Pedro H. C.
Número total de Autores: 6
Tipo de documento: Artigo Científico
Fonte: CHEMISTRY-A EUROPEAN JOURNAL; v. 23, n. 30, p. 7185-7190, MAY 29 2017.
Citações Web of Science: 5
Resumo

In hybrid materials containing plasmonic nanoparticles such as Au and Ag, charge-transfer processes from and to Au or Ag can affect both activities and selectivity in plasmonic catalysis. Inspired by the widespread utilization of commercial Si wafers in surface-enhanced Raman spectroscopy (SERS) studies, we investigated herein the effect of the native SiO2 layer on Si wafers over the surface plasmon resonance (SPR)-mediated activities of the Au and Ag nanoparticles (NPs). We prepared SERS-active plasmonic comprised of Au and Ag NPs deposited onto a Si wafer. Here, two kinds of Si wafers were employed: Si with a native oxide surface layer (Si/SiO2) and Si without a native oxide surface layer (Si). This led to Si/SiO2/Au, Si/SiO2/Ag, Si/Au, and Si/Ag NPs. The SPR-mediated oxidation of p-aminothiophenol (PATP) to p,p'-dimercaptoazobenzene (DMAB) was employed as a model transformation. By comparing the performances and band structures for the Si/Au and Si/Ag relative to Si/SiO2/Au and Si/SiO2/Ag NPs, it was found that the presence of a SiO2 layer was crucial to enable higher SPR-mediated PATP to DMAB conversions. The SiO2 layer acts to prevent the charge transfer of SPR-excited hot electrons from Au or Ag nanoparticles to the Si substrate. This enabled SPR-excited hot electrons to be transferred to adsorbed O-2 molecules, which then participate in the selective oxidation of PATP to DMAB. In the absence of a SiO2 layer, SPR-excited hot electrons are preferentially transferred to Si instead of adsorbed O-2 molecules, leading to much lower PATP oxidation. (AU)

Processo FAPESP: 15/21366-9 - Materiais híbridos contendo nanopartículas metálicas para aplicações catalíticas
Beneficiário:Pedro Henrique Cury Camargo
Linha de fomento: Auxílio à Pesquisa - Regular