Chandrani Roychowdhury
UHV-STEM

An annular dark field STEM image of carbon supported intermetallic PtPb nanoparticles. These find use as catalytic materials in PEM fuel cells. The nanoparticles were synthesized on carbon support to prevent their aggregation and increase the surface area of the material. In the image, the bright spots are that of PtPb nanoparticles about 3-6 nm in size, while the grey matrix is carbon black. The annular dark field detector in the UHV-STEM provides images sensitive to atomic number, hence the nanocrystalline PtPb particles ( high Z elements) are more clearly visible as bright spots as compared to the grey amorphous carbon background (Z= 6).

Dept: Chemistry and Chemical Biology
PI: Prof. Francis J. DiSalvo