Direct Visualization of Independent Ta Centers Supported on Two-Dimensional TiO<sub>2</sub> Nanosheets.

Bo, Zhenyu; Thornburg, Nicholas E; Peng, Lingxuan; Gutierrez Moreno, Jose Julio; Nolan, Michael; Marks, Laurence D; Notestein, Justin M · Nano Lett · 2019

basic_science · Level V

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Abstract

Highly dispersed, supported oxides are ubiquitous solid catalysts but can be challenging to characterize with atomic precision. Here, it is shown that crystalline anatase TiO<sub>2</sub> nanosheets (∼5 nm thick) are ideal supports for imaging highly dispersed active sites. Ta cations were deposited by several routes, and high-resolution high angle annular dark-field scanning transmission electron microscopy was used to determine the location of Ta with respect to the TiO<sub>2</sub> lattice and quantify Ta-Ta distances. In the best case, it is shown that >80% of Ta atoms are isolated from one another, whereas other techniques are blind to this critical catalytic property or give only qualitative estimates. TiO<sub>2</sub> nanosheets may prove to be a useful platform for other types of catalysis studies.