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Nano Lett. 2019 Sep 11;19(9):6363-6369. doi: 10.1021/acs.nanolett.9b02532. Epub 2019 Aug 8.

Etching-Assisted Route to Heterophase Au Nanowires with Multiple Types of Active Surface Sites for Silane Oxidation.

Author information

1
Frontier Institute of Science and Technology and State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710049 , China.
2
Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an , Shaanxi 710049 , China.
3
Institute of Advanced Electrochemical Energy and School of Materials Science and Engineering , Xi'an University of Technology , Xi'an , Shaanxi 710048 , China.
4
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute , Forschungszentrum Jülich , 52425 Jülich , Germany.
5
Structure of Materials Group , ESRF-The European Synchrotron CS40220 , 38043 Grenoble , France.

Abstract

The construction of multiple types of active sites on the surface of a metallic catalyst can markedly enhance its catalytic activity toward specific reactions. Here, we show that heterophase gold nanowires (Au NWs) with multiple types of active surface sites can be synthesized using an etching-assisted process, yielding the highest reported turnover frequency (TOF) for Au catalysts toward the silane oxidation reaction by far. We use synchrotron powder X-ray diffraction (PXRD) and aberration-corrected (scanning) transmission electron microscopy (TEM) to show that the Au NWs contain heterophase structures, planar defects, and surface steps. Moreover, the contribution to the catalytic performance from each type of active sites was clarified. Surface steps on the Au NW catalysts, which were identified using aberration-corrected (scanning) TEM, were shown to play the most important role in enhancing the catalytic performance. By using synchrotron PXRD, it was shown that a small ratio of metastable phases within Au NWs can enhance catalytic activity by a factor of 1.35, providing a further route to improve catalytic activity. Of the three types of surface active sites, surface terminations of planar defects such as twin boundaries (TB) and stacking faults (SF) are less active than metastable phases and surface steps for Au catalysts toward the silane oxidation reaction. Such an etching-assisted synthesis of heterophase Au NWs promises to open new possibilities for catalysis, plasmonic, optics, and electrical applications.

KEYWORDS:

Au nanowires; catalysis; heterophase; planar defects; steps

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