A water–gas shift reaction (WGS) is important and widely applied in the production of H₂. 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 SrTiO₃ (nominally SrTi_1–xCu_xO₃) 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 SrTiO₃, explaining why the segregated CuO phase on the SrTiO₃ surface is reduced to Cu during the catalytic reaction, while SrTiO₃ 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.

中文翻译：

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Cu改性SrTiO ₃钙钛矿对增强水煤气变换催化的实验和计算研究相结合

水煤气变换反应（WGS）很重要，并广泛应用于H ₂的生产中。铜改性钙钛矿是有希望的催化剂，可用于制氢的WGS反应。但是，这种材料的结构依赖性稳定性和反应途径仍然不清楚。在此，我们报告了具有催化活性的铜改性SrTiO ₃（名义上为SrTi _{1– x} Cu _x O ₃）通过改进的聚合前体方法制备。显微组织分析表明，所制备的材料中CuO相部分偏析。Operando X射线衍射和吸收光谱表明，在所有组合物的WGS反应条件下，CuO还原为稳定的金属相。在表征的材料中，x = 0.20的成分在300°C时表现出最高的转换频率，最低的活化能和最高的WGS速率。根据密度泛函计算，与SrTiO ₃相比，CuO的形成在能量上不利，这解释了为什么SrTiO ₃表面的偏析CuO相在催化反应过程中被还原为Cu，而SrTiO _3保留了下来。对于x＝ 0.20，偏析的CuO相的尺寸对于促进催化反应是最佳的。相反，较高的Cu含量（x = 0.3）导致较小的CuO颗粒聚集，从而导致较少的表面活性位点和催化性能的净降低。