Direct Imaging for Single Molecular Chain of Surfactant on CeO2 Nanocrystals

Xiaodong Hao; Chunlin Chen; Mitsuhiro Saito; Deqiang Yin; Kazutoshi Inoue; Seiichi Takami; Tadafumi Adschiri; Yuichi Ikuhara

doi:10.1002/smll.201801093

Direct Imaging for Single Molecular Chain of Surfactant on CeO₂ Nanocrystals

Small. 2018 Jul 1:e1801093. doi: 10.1002/smll.201801093. Online ahead of print.

Authors

Xiaodong Hao^{1

2}, Chunlin Chen¹, Mitsuhiro Saito³, Deqiang Yin¹, Kazutoshi Inoue¹, Seiichi Takami⁴, Tadafumi Adschiri^{1

2

5}, Yuichi Ikuhara^{1

3

6}

Affiliations

¹ WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan.
² Graduate School of Engineering, Tohoku University, Sendai, 980-8577, Japan.
³ Institute of Engineering Innovation, The University of Tokyo, Tokyo, 116-0013, Japan.
⁴ Graduate School of Engineering, Nagoya University, Nagoya, 464-8603, Japan.
⁵ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
⁶ Nanostructure Research Laboratory, Japan Fine Ceramics Center, Nagoya, 456-8587, Japan.

PMID: 29961954
DOI: 10.1002/smll.201801093

Abstract

Organic surfactant controls the synthesis of nanocrystals (NCs) with uniform size and morphology by attaching on the surface of NCs and further facilitates their assembly into ordered superstructure, which produces versatile functional nanomaterials for practical applications. It is essential to directly resolve the surfactant molecules on the surface of NCs to improve the understanding of surface chemistry of NCs. However, the imaging resolution and contrast are insufficient for a single molecule of organic surfactant on NCs. In this work, direct characterization of organic surfactant on CeO₂ NCs is conducted by using the state-of-the-art aberration corrected scanning transmission electron microscopy (STEM) imaging and electron energy loss spectra (EELS) techniques. The explicit evidence for the existence and distribution of organic surfactant on CeO₂ NCs are obtained on the atomic scale by EELS elemental mapping. Besides, STEM imaging parameters are systematically adjusted and optimized for the direct imaging of a single molecular chain of organic surfactant on CeO₂ NCs. Such direct visualization of organic surfactant molecule on the surface of NCs can be a significant step forward in the fields of nanomaterials surface chemistry and materials characterization.

Keywords: CeO2 nanocrystals; EELS mapping; STEM imaging; organic surfactant; surface chemistry.