title: In situ study of copper reduction in SrTi1-xCuxO3 nanoparticles.
abstract: Perovskite strontium titanate is a promising functional material for gas sensors and catalysis applications. Herein, we report the preparation of SrTi1-xCuxO3 nanoparticles with Cu doped in the B sites using a modified polymeric precursor method. This study describes in detail the structural and local atomic configurations for the substitution of Cu into the titanium sites and its reducibility using X-ray diffraction (XRD), field emission gun scanning and transmission electron microscopies (FEG-SEM and TEM), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) analyses. Our results indicate that copper is segregated for x≥ 0.06. After exposing the samples to a hydrogen-rich atmosphere at temperatures over 500 K, copper is reduced from Cu(2+) to metallic Cu. This reduction was attributed to copper atoms that originated primarily from the CuO phase.
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970, São Carlos, SP, Brazil. valmor@ifsc.usp.br.
authors.forename: Vitor C
authors.initials: VC
authors.lastname: Coletta
authors.forename: Francielle C F
authors.initials: FC
authors.lastname: Marcos
authors.forename: Francisco G E
authors.initials: FG
authors.lastname: Nogueira
authors.forename: Maria I B
authors.initials: MI
authors.lastname: Bernardi
authors.forename: Alain
authors.initials: A
authors.lastname: Michalowicz
authors.forename: Renato V
authors.initials: RV
authors.lastname: Gonçalves
authors.forename: Elisabete M
authors.initials: EM
authors.lastname: Assaf
authors.forename: Valmor R
authors.initials: VR
authors.lastname: Mastelaro