Cu and Co-modified SrTiO3 as materials for environmental applications

Abstract

SrTiO3-based powder materials with the general formula: SrTi0.98Me0.02O3, Sr0.95Ti0.98Me0.02O3 and Sr0.9Ti0.9Me0.1O3 where Me = Cu, Co were synthesised by modified sol-gel method followed by the proper thermal treatment. For all materials, the particle size distribution had a bimodal character. The Energy Dispersive Spectroscopy (EDS) results showed that cobalt was regularly and homogeneously distributed in the materials, while for Cu-modified samples the areas enriched with copper were observed. The phase analysis implied that for all materials strontium titanate was the main phase, nevertheless for materials with the higher amount of Cu/Co introduced the additional phases CuO/Co3O4 were also observed. However, Temperature Programmed Reduction (TPR) results indicated the presence of oxide phases in all obtained materials. In addition, these results confirmed a more effective incorporation of cobalt than copper into the titanium sublattice in the perovskite structure. Moreover, X-ray Photoelectron Spectroscopy (XPS) results showed that copper exists in the materials on +I and +II oxidation states while cobalt takes +II and +III. The catalytic tests of SrTiO3-based materials in NH3-SCR and NH3-SCO reactions showed that Co-modified SrTiO3 were active in ammonia oxidation, while Cu-modified samples were active in both reactions but in different temperature ranges.