In situ study of copper reduction in SrTi1−xCuxO3 nanoparticles†
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 Cu2+ to metallic Cu. This reduction was attributed to copper atoms that originated primarily from the CuO phase.