Synthesis of exfoliated CNT-metal-clay nanocomposite by chemical vapor deposition

A novel exfoliated carbon nanotube (CNT)-metal-clay composite was synthesized using catalyst decomposition of acetylene over nanoclay immobilized iron and platinum catalysts. The exfoliated nanoclay immobilized nano-sized catalysts, e.g. Pt or Fe, with diameters of a few nanometers was obtained via a metal organic chemical vapor deposition (MOCVD) process where the temperature of chemical vapor deposition (CVD) corresponds to an optimum decomposition temperature of organo-clay and a complete degradation of organic ligand of organic metal precursors. Counter diffusion and charge imbalance of nanoclay facilitated exfoliation of clay gallery and the uniform deposition and chemical bonding of the metal catalysts. Chemical bonding between metal catalysts and clay surfaces was verified using WAXD and transmission electron microscopy (TEM) analysis. The BET surface area and volume of the metal-clay were increased by 10 times and 3 times, respectively. The use of an organo-clay Cloisite 20A was the main course of clay exfoliation in the CVD process and the exfoliated structure was retained after the growth of MWNT as confirmed by WXRD analysis. Efforts were also made to prepare a nanocomposite membrane of MWNT-Pt-clay in Nafion for use in hydrogen fuel cells. The use of MWNT-Pt-clay in the Nafion membrane is believed to impart the membrane with simultaneously better mechanical strength, good self-humidifying performance and higher barrier resistance properties.