Surface engineering to tailor the active sites of SrTi0.9Co0.1O3-δ perovskite for CO oxidation

Abstract

We successfully engineered the surface properties of SrTiO3 perovskite for a carbon monoxide (CO) oxidation catalyst by substituting Co ions (10 at.%) into Ti-sites in SrTiO3 and subsequently applying a reductive thermal treatment. The substitution of Co ions in SrTiO3 induced charge imbalance, which was compensated by the generation of oxygen vacancies. During the subsequent reductive thermal treatment process, lattice oxygen species were released from the lattice of SrTiO3, leading to the further formation of oxygen vacancies and the segregation of Co cations on the catalyst surface. Thus, SrTi0.9Co0.1O3-δ catalyst showed superior activity compared to the pristine SrTiO3 in CO oxidation, and its catalytic activity was further enhanced after the thermal treatment. This improvement was due to the abundant surface oxygen vacancies generated by Co substitution and reductive thermal treatment. The presence of a surface Co-enriched phase increased the concentration of Co at the catalyst surface, providing more adsorption sites for CO. These findings demonstrate the effective control of the active sites (oxygen vacancies and B-site cations) in SrTiO3 using the two-step surface engineering method. This research contributes to the design of perovskite-oxide catalysts with reaction-tailored active sites by exploiting the synergistic effect of substitution and reductive thermal treatment methods.