Novel Sample Preparation for Operando TEM Studies

In situ studies of catalysts in the environmental transmission electron microscope (ETEM) are of great value to elucidate the structure of a catalyst under reaction conditions. This is important, since the structure of many catalysts change at elevated temperature in the presence of reactive gases [1-2]. One way to directly relate structure to activity is to measure the activity of the catalyst while it is being observed in the TEM, and this is called operando TEM. We measure catalytic activity by monitoring the amount of product gas from the catalytic reaction using electron energy-loss spectroscopy (EELS) and mass spectrometry [4]. The minute amount of catalyst present in a typically prepared powder TEM sample is usually not enough to produce a detectable amount of product gas. A new sample preparation technique was therefore developed to increase the amount of catalyst present in the microscope by at least an order of magnitude.