Environmental electron microscopy (ETEM) for catalysts with a closed E-cell with carbon windows.

In a standard high-resolution electron microscope (Jeol 3010), an environmental sample holder designed by Jeol, has been used for in situ observations at the atomic scale of catalysts, during a chemical reaction. Experiments have been performed in H(2) and O(2) at a pressure up to 4 mbar at room temperature, and in the case of H(2), at various temperatures until 350 degrees C. For the first time, Au and Pd clusters supported on TiO(2) and amorphous carbon have been observed with a windows-cell environmental electron microscopy (ETEM) system, with the resolution of the (1 1 1) lattice fringes. Au clusters have been cleaned in H(2) and have got the equilibrium shape of the fcc crystals during annealing. The same Au particles can be observed during successive treatments under O(2) and H(2). For Pd clusters in situ exposed to O(2) , the adhesion has decreased.