Yun Tae Gyu, Heo Yoon, Bin Bae Hyung, Chung Sung-Yoon
Department of Materials Science and Engineering, and KAIST Institute for the Nanocentury, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Korea.
KAIST Analysis Center, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Korea.
Nat Commun. 2021 Feb 5;12(1):824. doi: 10.1038/s41467-021-21055-0.
Although numerous studies on oxide catalysts for an efficient oxygen evolution reaction have been carried out to compare their catalytic performance and suggest new compositions, two significant constraints have been overlooked. One is the difference in electronic conduction behavior between catalysts (metallic versus insulating) and the other is the strong crystallographic surface orientation dependence of the catalysis in a crystal. Consequently, unless a comprehensive comparison of the oxygen-evolution catalytic activity between samples is made on a crystallographically identical surface with sufficient electron conduction, misleading interpretations on the catalytic performance and mechanism may be unavoidable. To overcome these limitations, we utilize both metallic (001) LaNiO epitaxial thin films together with metal dopants and semiconducting (001) LaCoO epitaxial thin films supported with a conductive interlayer. We identify that Fe, Cr, and Al are beneficial to enhance the catalysis in LaNiO although their perovskite counterparts, LaFeO, LaCrO, and LaAlO, with a large bandgap are inactive. Furthermore, semiconducting LaCoO is found to have more than one order higher activity than metallic LaNiO, in contrast to previous reports. Showing the importance of facilitating electron conduction, our work highlights the impact of the near-Fermi-level d-orbital states on the oxygen-evolution catalysis performance in perovskite oxides.
尽管已经开展了大量关于用于高效析氧反应的氧化物催化剂的研究，以比较它们的催化性能并提出新的组成，但有两个重要限制被忽视了。一个是催化剂之间电子传导行为的差异（金属性与绝缘性），另一个是晶体中催化作用对晶体学表面取向的强烈依赖性。因此，除非在具有足够电子传导的晶体学相同表面上对样品之间的析氧催化活性进行全面比较，否则对催化性能和机理的误导性解释可能不可避免。为了克服这些限制，我们使用了金属性的（001）LaNiO外延薄膜以及金属掺杂剂，还有带有导电中间层支撑的半导体性的（001）LaCoO外延薄膜。我们发现，Fe、Cr和Al有利于增强LaNiO中的催化作用，尽管它们具有大带隙的钙钛矿对应物LaFeO、LaCrO和LaAlO没有活性。此外，与之前的报道相反，发现半导体性的LaCoO的活性比金属性的LaNiO高一个多数量级。我们的工作表明了促进电子传导的重要性，突出了近费米能级d轨道态对钙钛矿氧化物析氧催化性能的影响。
