In Situ Industrial Bimetallic Catalyst Characterization using Scanning Transmission Electron Microscopy and X-ray Absorption Spectroscopy at One Atmosphere and Elevated Temperature.

We have developed a new experimental platform for in situ scanning transmission electron microscope (STEM) energy dispersive X-ray spectroscopy (EDS) which allows real time, nanoscale, elemental and structural changes to be studied at elevated temperature (up to 1000 °C) and pressure (up to 1 atm). Here we demonstrate the first application of this approach to understand complex structural changes occurring during reduction of a bimetallic catalyst, PdCu supported on TiO , synthesized by wet impregnation. We reveal a heterogeneous evolution of nanoparticle size, distribution, and composition with large differences in reduction behavior for the two metals.

Real-time imaging and local elemental analysis of nanostructures in liquids.

A new design of in situ liquid cells is demonstrated, providing the first nanometer resolution elemental mapping of nanostructures in solution. The technique has been applied to investigate dynamic liquid-phase synthesis of core-shell nanostructures and to simultaneously image the compositional distribution for multiple elements within the resulting materials.

X-ray energy-dispersive spectrometry during in situ liquid cell studies using an analytical electron microscope.

The use of analytical spectroscopies during scanning/transmission electron microscope (S/TEM) investigations of micro- and nano-scale structures has become a routine technique in the arsenal of tools available to today's materials researchers. Essential to implementation and successful application of spectroscopy to characterization is the integration of numerous technologies, which include electron optics, specimen holders, and associated detectors. While this combination has been achieved in many instrument configurations, the integration of X-ray energy-dispersive spectroscopy and in situ liquid environmental cells in the S/TEM has to date been elusive.