ABSTRACT

LaFeO₃ films were deposited to a thickness of 0.5 nm onto amorphous SiO₂ by Atomic Layer Deposition and used as supports for Pt. Uniform coverage of the SiO₂ was demonstrated by Scanning Transmission Electron Microscopy (STEM) and Temperature Programmed Desorption (TPD) of 2-propanol. The films were found to be amorphous to X-Ray Diffraction, but the reducibility of the Fe in the films and the ability of the films to maintain high Pt dispersions following harsh redox treatments suggested that the perovskite phase was formed on a short length scale. Similar to results found on Pt/LaFeO₃/MgAl₂O₄, Pt/LaFeO₃/SiO₂ catalysts maintained a high Pt dispersion following redox cycling at 1073 K and showed high activity for CO oxidation following high-temperature reduction. The implications for using these materials is discussed.

摘要

LaFeO _{3薄膜通过原子层沉积在无定形SiO 2}上沉积至0.5nm的厚度，并用作Pt的载体。通过 2-丙醇的扫描透射电子显微镜 (STEM) 和程序升温脱附 (TPD) 证明了 SiO ₂的均匀覆盖。X 射线衍射发现这些薄膜是无定形的，但薄膜中 Fe 的可还原性和薄膜在苛刻的氧化还原处理后保持高 Pt 分散的能力表明钙钛矿相是在短尺度上形成的。类似于在 Pt/LaFeO ₃ /MgAl ₂ O ₄、Pt/LaFeO ₃ /SiO _{2上发现的结果}催化剂在 1073 K 的氧化还原循环后保持高 Pt 分散，并在高温还原后显示出高的 CO 氧化活性。讨论了使用这些材料的含义。