Effect of catalyst preparation on the yield of carbon nanotube growth

MARIANO ESCOBAR; GERARDO H. RUBIOLO; ROBERTO CANDAL; SILVIA GOYANES

PHYSICA B - CONDENSED MATTER

Elsevier

Lugar: Amsterdam; Año: 2009 vol. 404 p. 2795 - 2798

0921-4526

Multi-wallcarbonnanotubes(MWCNTs)weresynthesizedbycatalyticchemicalvapordeposition(CVD) on catalyticironnanoparticlesdispersedinasilicamatrix,preparedbysolgelmethod.Inthis contribution,variationofgelationconditiononcatalyststructureanditsinfluenceontheyieldof carbonnanotubesgrowthwasstudied.Theprecursorutilizedweretetraethyl-orthosilicateandiron nitrate. Thesolsweredriedattwodifferenttemperaturesinair(25or80 1C) andthentreatedat450 1C for 10h.Thexerogelswereintroducedintothechamberandreducedinahydrogen/nitrogen(10%v/v) atmosphereat600 1C. MWCNTswereformedbydepositionofcarbonatomsfromdecompositionof acetylene at700 1C. ThesystemgelledatRTshowsayieldof100%respecttoinitialcatalystmass whereas theyieldofthatgelledat80 1C waslowerthan10%.Differentcrystallinephasesareobserved for bothcatalystsineachstepoftheprocess.Moreover,TPRanalysisshowsthatironoxidecanbe efficientlyreducedtometallicirononlyinthesystemgelledatroomtemperature.Carbonnanotubes displayadiameterofabout25–40nmandseveralmicronlengths.ThegrowthmechanismofMWCNTs is basegrowthmodeforbothcatalysts. 1C) andthentreatedat450 1C for 10h.Thexerogelswereintroducedintothechamberandreducedinahydrogen/nitrogen(10%v/v) atmosphereat600 1C. MWCNTswereformedbydepositionofcarbonatomsfromdecompositionof acetylene at700 1C. ThesystemgelledatRTshowsayieldof100%respecttoinitialcatalystmass whereas theyieldofthatgelledat80 1C waslowerthan10%.Differentcrystallinephasesareobserved for bothcatalystsineachstepoftheprocess.Moreover,TPRanalysisshowsthatironoxidecanbe efficientlyreducedtometallicirononlyinthesystemgelledatroomtemperature.Carbonnanotubes displayadiameterofabout25–40nmandseveralmicronlengths.ThegrowthmechanismofMWCNTs is basegrowthmodeforbothcatalysts.