Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Sci Rep. 2011;1:27. doi: 10.1038/srep00027. Epub 2011 Jun 30.
Reduction and oxidation in transition-metal oxides are keys to develop technologies related to energy and the environment. Here we report the selective topochemical reduction observed when artificial superlattices with transition-metal oxides are treated at a temperature below 300 °C with CaH(2). CaFeO(2)/SrTiO(3) infinite-layer/perovskite artificial superlattice thin films were obtained by low-temperature reduction of CaFeO(2.5)/SrTiO(3) brownmillerite/perovskite artificial superlattice thin films. By the reduction only the CaFeO(2.5) layers in the artificial superlattices were reduced to the CaFeO(2) infinite layers whereas the SrTiO(3) layers were unchanged. The observed low-temperature reduction behaviors strongly suggest that the oxygen ion diffusion in the artificial superlattices is confined within the two-dimensional brownmillerite layers. The reduced artificial superlattice could be reoxidized, and thus, the selective reduction and oxidation of the constituent layers in the perovskite-structure framework occur reversibly.
过渡金属氧化物中的还原和氧化是开发与能源和环境相关技术的关键。在这里，我们报告了当人工超晶格用钙氢化物（CaH(2)）在 300°C 以下处理时观察到的选择性拓扑化学还原。通过低温还原CaFeO(2.5)/SrTiO(3)钙钛矿型布朗米勒/钙钛矿型人工超晶格薄膜，得到了CaFeO(2)/SrTiO(3)无限层/钙钛矿型人工超晶格薄膜。通过还原，只有人工超晶格中的 CaFeO(2.5)层被还原为 CaFeO(2)无限层，而 SrTiO(3)层没有变化。观察到的低温还原行为强烈表明，人工超晶格中的氧离子扩散被限制在二维布朗米勒层内。还原后的人工超晶格可以被再氧化，因此，钙钛矿结构骨架中组成层的选择性还原和氧化可以可逆地发生。
