If your sample is nano-powder, a small amount of your catalyst nano-powder sample ( one or two grains) is dispersed in ethanol (10 ml). Every step is taken very carefully to avoid the contamination. Place a droplet of the catalyst nano-powder suspension on the TEM grid using a glass dropper (cleaned and washed) then allow the ethanol to evaporate (minimum 24 hours). after completing this protocol sample grid insert the sample holder and insert the TEM.

I'd like to suggest Vishal's method except the solvent acetone. For the solvent, it is safer to use ethanol (the other two answers above).