Two series of strontium titanates doped with Ni, Co, or Cu with general formula of SrTi_1-xMe_xO₃ for Sr-stoichiometric and Sr_0.95Ti_1−xMe_xO₃ for Sr-non-stoichiometric materials (where Me = Ni, Co or Cu and x were 0.02 and 0.06) were obtained by the wet chemical method. The samples were calcinated at 900, 950, and 1050 °C and characterized in terms of their structural properties (XRD), the possibility of undergoing the reduction and oxidation reactions (TPR/TPOx), and catalytic properties. All obtained materials were multiphase and although the XRD analysis does not confirm the presence of Ni, Co, and Cu oxides (with one exception for Cu-doped sample), the TPR/TPOx profiles show reduction peaks that can be attributed to the reduction of these oxides which may at first appear in an amorphous form. Catalytic tests in dry reforming of methane reaction showed that the highest catalytic activity was achieved for Ni-doped materials (up to 90% of CH₄ conversion) while Co and Cu-doped samples showed only a very slight catalytic effect. Additionally, the decrease in methane conversion with an increasing calcination temperature was observed for Ni-doped strontium titanates.

Two wet-synthesis methods: citrate-combustion and modified (with PVA addition) Pechini synthesis were used to obtain Co-doped strontium titanate with assumed chemical compositions of SrTi_1−xCo_xO₃ (where x = 0.02; 0.06; 0.10). All samples were calcined at 900 °C and sintered at 1200 °C, with PVA series being also calcined at 700 and 800 °C, since TG measurements indicated for this method materials lower minimal calcination temperature than for the citrate-combustion series materials. In general, the modified Pechini approach lowers calcination temperature of materials (up to 200 °C) and produces more structurally homogeneous materials than in the case of the citrate-combustion methods. However, the HT XRD measurements reveal the presence of extra cobalt oxide phases in pva_STO_xCo materials that were not visible using conventional XRD measurements. The presence of cobalt oxide has been confirmed for both series of materials based on TPR tests. Moreover, these measurements indicate the incorporation of some amount of cobalt into the perovskite structure. The fact of substituting titanium with cobalt in SrTiO₃ structure seems to be confirmed by the results of XAS studies. Additionally, XAS results allowed us to state that Co²⁺/Co³⁺ ratio fell as cobalt loading increased in the materials. The examination of SrTiO₃ lattice parameter changes for sintered samples is consistent with the findings of the XAS tests and indicates that cobalt adopts +2 oxidation state in the case of the material with the lowest Co content, and the share of Co³⁺ increases with the growth of the Co amount introduced into the system.