Hahn Christopher, Hatsukade Toru, Kim Youn-Geun, Vailionis Arturas, Baricuatro Jack H, Higgins Drew C, Nitopi Stephanie A, Soriaga Manuel P, Jaramillo Thomas F
Department of Chemical Engineering, Stanford University, Stanford, CA 94305.
SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, CA 94025.
Proc Natl Acad Sci U S A. 2017 Jun 6;114(23):5918-5923. doi: 10.1073/pnas.1618935114. Epub 2017 May 22.
In this study we control the surface structure of Cu thin-film catalysts to probe the relationship between active sites and catalytic activity for the electroreduction of CO to fuels and chemicals. Here, we report physical vapor deposition of Cu thin films on large-format (∼6 cm) single-crystal substrates, and confirm epitaxial growth in the <100>, <111>, and <751> orientations using X-ray pole figures. To understand the relationship between the bulk and surface structures, in situ electrochemical scanning tunneling microscopy was conducted on Cu(100), (111), and (751) thin films. The studies revealed that Cu(100) and (111) have surface adlattices that are identical to the bulk structure, and that Cu(751) has a heterogeneous kinked surface with (110) terraces that is closely related to the bulk structure. Electrochemical CO reduction testing showed that whereas both Cu(100) and (751) thin films are more active and selective for C-C coupling than Cu(111), Cu(751) is the most selective for >2e oxygenate formation at low overpotentials. Our results demonstrate that epitaxy can be used to grow single-crystal analogous materials as large-format electrodes that provide insights on controlling electrocatalytic activity and selectivity for this reaction.
在本研究中，我们控制铜薄膜催化剂的表面结构，以探究活性位点与将CO电还原为燃料和化学品的催化活性之间的关系。在此，我们报道了在大面积（约6厘米）单晶衬底上物理气相沉积铜薄膜，并使用X射线极图确认了在<100>、<111>和<751>取向的外延生长。为了理解体相结构与表面结构之间的关系，对Cu(100)、(111)和(751)薄膜进行了原位电化学扫描隧道显微镜研究。研究表明，Cu(100)和(111)的表面吸附晶格与体相结构相同，而Cu(751)具有与体相结构密切相关的、带有(110)平台的异质扭结表面。电化学CO还原测试表明，虽然Cu(100)和(751)薄膜在C-C偶联方面比Cu(ll1)更具活性和选择性，但Cu(751)在低过电位下对生成>2e含氧化合物的选择性最高。我们的结果表明，外延可用于生长单晶类似材料作为大面积电极，从而为控制该反应的电催化活性和选择性提供见解。
