Recent Advances in Chemical Synthesis Methodology of Inorganic Materials and Theoretical Computation of Metal Nanoparticles/Carbon Interfaces

Abstract

Using density functional theory (DFT) the interface of metal nanoparticles to cup-stacked carbon nanofibers were modelled and studied for binding interactions and characterization signatures for different crystal facets of mono-metallic Pt and the PtRu alloy. The strongest metal–carbon interaction is predicted for a (111) facet attached to a zigzag edge. The anchoring of the PtRu metal is found to have pronounced effects on the surface composition of the alloy. Whereas the bare surface is rich in Pt, the interface with carbon favors the stoichiometric bulk composition. Core level binding energies of carbon, platinum and ruthenium are found to provide valuable signatures of the interface and give means to interpret future high resolution photoemission core level spectroscopy experiments. A new synthesis methodology, namely Confined-Plume Chemical Deposition (CPCD), has been developed within the Lukehart Group. Originally this technique utilized the free electron laser (FEL) at Vanderbilt University; however this laser is not widely available to other researchers. As such, considerable effort has been made to extend CPCD to table-top lasers. CPCD represents a much faster synthesis methodology, capable of depositing desired materials directly on the support for application. Successful application of CPCD to several different research interests, namely magnetic field assisted deposition of Fe₃O₄, deposition Au on onion, and formation of lanthanide doped YBO₃ powders, is shown. Dysprosium and Holmium have the two highest magnetic susceptibilities of any elements. This makes them ideal materials for detecting small changes in electrical flow and thus magnetic flux. Dysprosium was produced by ball milling metallic flakes in a planetary ball mill under nitrogen atmosphere. This technique produces flat 5 to 20 μm metallic particles, but spherical particles are desired. Tumble milling was used to round these particles into 1 to 10 μm particles. These metallic dysprosium particles are then coated with platinum through a reductive transmetallization reaction with platinum hexafluoroacetylacetonate.