title: On the High Sensitivity of the Electronic States of 1 nm Gold Particles to Pretreatments and Modifiers.
abstract: In this paper, the effect of modifiers and pretreatments on the electronic states of 1 nm gold nanoparticles (AuNPs) supported on silica was systematically studied. AuNPs deposited on silica (particle size of 2-4 nm) modified with Ce, La and Fe oxides, were studied by FTIR of adsorbed CO after different redox treatments at 100, 300 and 500 °C. This study was conducted at room temperature to allow detecting the electronic states of gold, which is more likely involved in CO oxidation at the same temperature. AuNP size distribution was measured by HRTEM. It is shown that the electronic state of gold species (Aun(δ-), Au⁰, Aun(δ+), Au⁺) in 1 nm AuNPs is sensitive to the modifier as well as to the temperatures of redox pretreatments. Supports modified with the same additives but containing larger AuNPs (~3, 4, 5, and 7 nm) were also studied. They showed that Au⁰ remains stable irrespective of additives and redox pretreatments, indicating no significant effect of such treatments on the electronic properties of larger AuNPs. Samples with a predominant AuNP size of 2 nm are an intermediate case between these two groups of materials.
authors.affiliation: Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico. martynyuk_oksana@mail.ru.|Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia. martynyuk_oksana@mail.ru.
authors.forename: Oxana
authors.initials: O
authors.lastname: Martynyuk
authors.affiliation: Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico. Julia.Kotolevich@gmail.com.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Kotolevich
authors.affiliation: Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico. rovera91@hotmail.com.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Vélez
authors.affiliation: Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada 22860, Mexico. efren507.507@gmail.com.
authors.forename: Jesus Efren
authors.initials: JE
authors.lastname: Cabrera Ortega
authors.affiliation: Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico. tiznado@cnyn.unam.mx.
authors.forename: Hugo
authors.initials: H
authors.lastname: Tiznado
authors.affiliation: Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico. trino@cnyn.unam.mx.
authors.forename: Trino
authors.initials: T
authors.lastname: Zepeda Partida
authors.affiliation: CONACYT Research Fellow at Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada, 22860, Mexico. jmota@cnyn.unam.mx.
authors.forename: Josué D
authors.initials: JD
authors.lastname: Mota-Morales
authors.affiliation: Department of Physical and Analytical Chemistry, Tomsk Polytechnic University, Tomsk 634050, Russia. pestryakov2005@yandex.ru.
authors.forename: Alexey
authors.initials: A
authors.lastname: Pestryakov
authors.affiliation: Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México (UNAM), Ensenada 22860, Mexico. nina@cnyn.unam.mx.
authors.forename: Nina
authors.initials: N
authors.lastname: Bogdanchikova
mesh_terms: D000327:Adsorption; D004583:Electrons; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D006046:Gold; D012822:Silicon Dioxide
keywords: 1 nm gold; FTIR CO; electron stage of gold; sensitivity to pretreatment