Abstract
The filling of multi-walled carbon nanotubes (MWNTs) or vapor grown carbon fibers (VGCFs) with Pb2+ salts was investigated using two different methods. Using a two-step process, we were successful in filling VGCFs, but not MWNTs; nonetheless, there was no X-ray absorption from the tubes. In contrast, with an in-situ method, no filling of carbon nanotubes (CNTs) with metal or metal salts was observed; however, significant X-ray absorption was based on metal salts present on the outside of the CNTs. The presence of surface coating with good X-ray absorption led to the study of coating MWNTs, VGCFs, and single walled carbon nanotubes (SWNTs) with PbS or Bi2S3 using liquid phase deposition using the aid of surfactants and acid treated tubes. Acid treated tubes give a more even growth of the metal sulfide nanoparticles compared to the surfacted tubes. The PbS coated VGCFs show a comparable transmission of X-rays as commercially available 100% lead lined apron, but slightly lower attenuation per g/cm2 of material.