title: Easy Access to Metallic Copper Nanoparticles with High Activity and Stability for CO Oxidation.
abstract: Copper catalysts are very promising, affordable alternatives for noble metals in CO oxidation; however, the nature of the active species remains unclear and differs throughout previous reports. Here, we report the preparation of 8 nm copper nanoparticles (Cu NPs), with high metallic content, directly deposited onto the surface of silica nanopowders by magnetron sputtering deposition. The as-prepared Cu/SiO2 contains 85% Cu0 and 15% Cu2+ and was enriched in the Cu0 phase by H2 soft pretreatment (96% Cu0 and 4% Cu2+) or further oxidized after treatment with O2 (33% Cu0 and 67% Cu2+). These catalysts were studied in the catalytic oxidation of CO under dry and humid conditions. Higher activity was observed for the sample previously reduced with H2, suggesting that the presence of Cu-metal species enhances CO oxidation performance. Inversely, a poorer performance was observed for the sample previously oxidized with O2. The presence of water vapor caused only a small increase in the temperature require for the reaction to reach 100% conversion. Under dry conditions, the Cu NP catalyst was able to maintain full conversion for up to 45 h at 350 °C, but it deactivated with time on stream in the presence of water vapor.
authors: †Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, São Paulo 05508-000, São Paulo, Brazil.
authors: Renato V
authors: RV
authors: Gonçalves
authors: §Unité de Catalyse et Chimie du Solide, UCCS, UMR CNRS 8181, F-59655 Villeneuve d'Ascq, France.|⊥Université Lille Nord de France, F-59000 Lille, France.
authors: Robert
authors: R
authors: Wojcieszak
authors: ||Instituto de Física, Universidade Federal do Mato Grosso do Sul, Avenida Costa e Silva s/n, Campo Grande 79070-900, Mato Grosso do Sul, Brazil.
authors: Heberton
authors: H
authors: Wender
authors: #Laboratório Nacional de Luz Síncrotron (LNLS), Rua Giuseppe Maximo Scolfaro 10.000, Campinas 13083-970, São Paulo Brazil.
authors: Carlos
authors: C
authors: Sato B Dias
authors: †Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, São Paulo 05508-000, São Paulo, Brazil.
authors: Lucas L R
authors: LL
authors: Vono
authors: □Universidade de Caxias do Sul, Bento Gonçalves 95700-000, Rio Grande do Sul, Brazil.
authors: Dario
authors: D
authors: Eberhardt
authors: △Instituto de Física, Universidade Federal do Rio Grande do Sul, Avenida Bento Gonçalves 9500, Rio Grande do Sul, Brazil.
authors: Sergio R
authors: SR
authors: Teixeira
authors: †Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, São Paulo 05508-000, São Paulo, Brazil.
authors: Liane M
authors: LM
authors: Rossi
keywords: CO oxidation; carbon monoxide; catalysis; copper nanoparticles; magnetron sputtering deposition