INTECIN   20395
INSTITUTO DE TECNOLOGIAS Y CIENCIAS DE LA INGENIERIA "HILARIO FERNANDEZ LONG"
Unidad Ejecutora - UE
artículos
Título:
Effect of catalyst preparation on the yield of carbon nanotube growth
Autor/es:
M. ESCOBAR; G. RUBIOLO; R. CANDAL; S. GOYANES
Revista:
PHYSICA B - CONDENSED MATTER
Editorial:
Elsevier Science
Referencias:
Año: 2009 vol. 404 p. 2795 - 2798
ISSN:
0921-4526
Resumen:
st1:*{behavior:url(#ieooui) } <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-hyphenate:none; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB; mso-fareast-language:#00FF;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Multi-wall carbon nanotubes (MWCNTs) were synthesized by catalytic chemical vapor deposition (CVD) on catalytic iron nanoparticles dispersed in a silica matrix, prepared by sol gel method. In this contribution, variation of gelation condition on catalyst structure and its influence on the yield of carbon nanotubos growth was studied. The precursor utilized were tetraethyl-orthosilicate and iron nitrate. The sols were dried at two different temperatures in air (25 or 80ºC) and then treated at 450°C for 10 h. The xerogels were introduced into the chamber and reduced in a hydrogen/nitrogen (10% v/v) atmosphere at 600°C. MWCNTs were formed by deposition of carbon atoms from decomposition of acetylene at 700°C. The system gelled at RT shows a yield of 100% respect to initial catalyst mass whereas the yield of that gelled at 80ºC was lower than 10%. Different crystalline phases are observed for both catalysts in each step of the process. Moreover, TPR analysis shows that iron oxide can be efficiently reduced to metallic iron only in the system gelled at room temperature. Carbon nanotubes display a diameter of about 25-40 nm and several micron lengths. The growth mechanism of MWCNTs is base growth mode for both catalysts.