Department of Materials Science and Engineering , Tel Aviv University , Tel Aviv 69978001 , Israel.
Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208-3108 , United States.
ACS Appl Mater Interfaces. 2019 Sep 18;11(37):33850-33858. doi: 10.1021/acsami.9b09404. Epub 2019 Sep 10.
The influence of planar defects, in the form of stacking faults, within perovskite oxides on catalytic activity has received little attention because controlling stacking-fault densities presents a major synthetic challenge. Furthermore, stacking faults in ceramics are not thought to appreciably impact surface chemistry, which partly explains why their direct effect on catalysis is generally ignored. Here, we show that Ruddlesden-Popper (RP) stacking faults in otherwise stoichiometric LaFeO can be broadly controlled by modulating the ceramic synthesis route. Electronic structure calculations along with electron microscopy and spectroscopy show that energetically favorable RP faults occur both near the surface and in bunches and enhance CO oxidation kinetics. Density functional theory (DFT) + shows that subsurface RP faults strengthen the adsorption and co-adsorption of CO, O, and O, which could lower the apparent activation energy of CO oxidation on faulted catalysts compared to that on their pristine counterparts. Our work suggests that planar defects should be considered a new and useful feature in hierarchal nanoscale design of future catalysts.
层状缺陷（如堆垛层错）对钙钛矿氧化物催化活性的影响尚未得到太多关注，因为控制堆垛层错密度是一个重大的合成挑战。此外，陶瓷中的堆垛层错被认为不会显著影响表面化学，这在一定程度上解释了为什么它们对催化的直接影响通常被忽略。在这里，我们表明，通过调节陶瓷合成路线，可以广泛控制其他方面化学计量的 LaFeO 中的 Ruddlesden-Popper（RP）堆垛层错。电子结构计算以及电子显微镜和光谱表明，在表面附近和束中都会发生能量有利的 RP 层错，并增强 CO 氧化动力学。密度泛函理论（DFT）+表明，亚表面 RP 层错会增强 CO、O 和 O 的吸附和共吸附，这可能会降低有缺陷催化剂上 CO 氧化的表观活化能，与无缺陷催化剂相比。我们的工作表明，在未来催化剂的分级纳米设计中，平面缺陷应该被视为一种新的、有用的特征。
