Transmission electron microscopy studies of the Pd-C films obtained by physical and chemical vapor deposition

Transmission Electron Microscopy (TEM) analysis of carbonaceous films that contain palladium nanoparticles were carried out. These layers will be used in next-generation hydrogen sensors. The investigated films were obtained in Physical Vapor Deposition (PVD) and followed in Chemical Vapor Deposition (CVD) processes. For TEM analysis, cross-sections specimen (lamella) of both samples (i.e. PVD and PVD/CVD) were prepared with the usage of Focus Ion Beam (FIB). TEM analysis of the cross-sections determined the films' thickness, which were similar to 200 nm and similar to 300 nm for PVD and PVD/CVD films respectively. The greater thickness of the PVD/CVD films was associated with xylene decomposition and consecutive formation of porous structure. Our studies allowed to obtain some information about the distribution of palladium crystallites and porous carbon in the both layers of Pd-C. Furthermore, aggregation of small (similar to 2 nm) Pd nanocrystallites around the larger ones was observed for PVD and PVD/CVD films. In the PVD/CVD films a polycrystalline palladium have been observed. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.