The synthesis, characterization and applications of heteroatom doped glassy carbon materials.

摘要

An investigation of the synthesis, characterization and applications of a new class of glassy carbon materials was accomplished. The incorporation of non-carbon atoms in glassy carbon was achieved via low temperature thermal treatment (600{dollar}spcirc{dollar}C) of derivatized poly(phenylene diacetylene) oligomeric precursors. The glassy carbon materials herein contain chlorine, fluorine and platinum. The platinum doped glassy carbon materials were used to determine the effect of platinum particle size on the catalytic reforming reactions of n-hexane. It was determined that the selectivity toward aromatization increased with decreasing platinum particle size. By controlling platinum particle size via manipulation of the platinum doping levels in the oligomeric precursors, we have eliminated such variables as particle-support interactions and support acidity/basicity, microstructure and composition in the catalysts. This allows us to unambiguously observe the effects of changes in product distribution with changes in platinum particle size.; The investigation of halogen doped glassy carbon provided unique insight into the structure and property relationships of electrode surfaces and materials. The incorporation of the dopants resulted in dramatic changes in the physical and chemical properties of the materials. Specifically, an investigation of the surface energies of the glassy carbon materials found a decrease in the surface energy of fluorine doped glassy carbon relative to chlorine doped glassy carbon which was lower than non-doped glassy carbon. This effect is central to our investigations of electrocatalytic surfaces because the energetics of solid and liquid interfaces are critical to the efficiency of electrochemical processes. In order to take advantage of the robust, low surface energy, electrically conductive properties of fluorine doped glassy carbon in fuel cell electrode applications, a glassy carbon material containing both fluorine and platinum was prepared. These materials possessed, within experimental error, the same electrocatalytic response for proton and dioxygen reduction as polycrystalline platinum wire, yet contained only {dollar}sim{dollar}0.5 atom % platinum.