Cu-Modified SrTiO₃Perovskites Toward Enhanced Water–Gas Shift Catalysis: A Combined Experimental and Computational Study

A water–gas shift reaction (WGS) is important and widely applied in the production of H 2 . Cu-modified perovskites are promising catalysts for WGS reactions in hydrogen generation. However, the structure-dependent stability and reaction pathways of such materials remain unclear. Herein, we report catalytically active Cu-modified SrTiO 3 (nominally SrTi 1– x Cu x O 3 ) prepared by a modified polymeric precursor method. Microstructural analysis revealed a partially segregated CuO phase in the as-prepared materials. Operando X-ray diffraction and absorption spectroscopy showed the reduction of CuO into a stable metallic phase under conditions of WGS reactions for all compositions. Among the characterized materials, the x = 0.20 composition showed the highest turnover frequency, lowest activation energy, and the highest WGS rate at 300 °C. According to density functional calculations, the formation of CuO is energetically less favorable compared with SrTiO 3, explaining why the segregated CuO phase on the SrTiO 3 surface is reduced to Cu during the catalytic reaction, while SrTiO 3 remains. For x = 0.20, the size of the segregated CuO phase is optimum for facilitating the catalytic reaction. In contrast, a higher Cu content ( x = 0.3) results in an aggregation of smaller CuO particles, resulting in fewer surface active sites and a net decrease in catalytic performance.