Silver/Silicon nanowires/copper nanoparticles heterojunction for methyl orange degradation by heterogeneous photocatalys
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.641
Silver/Silicon nanowires/copper nanoparticles heterojunction for methyl orange degradation by heterogeneous photocatalysis under visible irradiation María Reina García Robles1, José de Jesús Pérez Bueno*,1, Crista Selene Arteaga Syllas1,2, Maria Luisa Mendoza López3, Federico Manriquez Guerrero1 1
Centro de Investigación y Desarrollo Tecnológico en Electroquímica S.C., Parque Tecnológico Querétaro s/n, Sanfandila, Pedro Escobedo, Querétaro, 76703, MÉXICO. [email protected]; * [email protected]
2 Universidad Tecnológica de Tula-Tepeji, Av. Universidad Tecnológica No. 1000, El Carmen, Tula de Allende, Hidalgo, 42830, MÉXICO. [email protected]
3 Tecnológico Nacional de México, Instituto Tecnológico de Querétaro, Av. Tecnológico s/n Esq. M. Escobedo Col. Centro C.P.76000 Querétaro, Qro. MÉXICO. E-mail: [email protected]
ABSTRACT
In this work, the degradation of methyl orange (MO) was analyzed by direct light with visible radiation (λ > 450 nm) of a dye solution in the presence of silicon nanowires (SiNWs) or silicon nanowires with copper nanoparticles (SiNWs-CuNPs). The SiNWs were synthesized by metal assisted etching from monocrystalline silicon wafers in aqueous HF / AgNO3 solution, and the CuNPs were deposited on the SiNWs via electroless. Discoloration with visible irradiation of aqueous methyl orange solution (C14H14N3NaOS) in the presence of SiNWs showed an efficiency of 71% after 120 min of illumination. The deposition of copper nanoparticles on the nanowires improves the efficiency of the photocatalytic reaction achieving 89% discoloration after 120 min exposure to visible light. The MO photocatalytic degradation with visible radiation in aqueous solution shows to be efficient in discoloration reaching up to 92% in a time of 150 min in the presence of SiNWs-CuNPs.
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INTRODUCTION Photocatalysis is considered an advanced oxidation process capable of directly converting solar energy into chemical energy. It is based on the degradation of pollutants on the surface of a photocatalyst (semiconductor) excited with radiant energy (visible or UV), thus representing an attractive strategy for the generation of renewable energy and environmental remediation. The photocatalytic process consists of four stages, the photoexcitation, where the semiconductor causes an excess of electrons in the conduction band and positive holes in the valence band, that is, gives rise to electron-hole pairs (e- h+) [1]. Second, the separation and transport of charge to the active sites on the catalyst surface and, simultaneously, recombination of the electron-hole pair. Finally, the reduction-oxidation reactions where the e- - h+ pairs in the active sites are used as oxidizing or reducing agents. However, th
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