Preparation of Catalyst Samples for SEM Analyses

The preparation of most samples for SEM analysis is usually straightforward. For most of the metal catalyst, the sample can be analyzed without any pretreatment ( as it is ). However, it is important that the sample be dry, including preservation in a vacuum chamber, and be conductive. For catalysts in powder form, the material 

In many cases, gold may be used for the coating, which is usually done by sputtering. A thin film of Au is deposited on the catalyst, which occurs by means of plasma, by applying a voltage (usually 1-2 kV) to a gas, which may be air, under very low pressure. 

The thickness of the deposited metal must be controlled (in the range of 10-30 nm, depending on the material), which is relevant for catalysts. A very thin but heterogeneous layer may lead to insufficient emission amount of secondary electrons and may change the interpretation of the analysis of the surface material. A thick layer, however, can generate artifacts and mask details and/or change the 

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