The role of metal nanoparticles in the catalytic production of single-walled carbonnanotubes—a review

Abstract

Recent progress in chemical vapour deposition and aerosol synthesis of single-walled carbonnanotubes (SWCNTs) is reviewed with an emphasis on the role of metal nanoparticles inthe processes. The effect of the various parameters on SWCNT formation is reported on thebasis of published experiments. Evolution of the catalyst particle size distribution due tocollision, sintering and evaporation of metal during SWCNT synthesis is discussed.The active catalyst has been demonstrated to be in a reduced metal form bycomparison of the experimental data and calculations regarding the equilibriumconcentration of carbon and oxygen in iron. Also the effect of the catalyst particle size onmelting temperature and carbon solubility in metal is discussed. The stability ofdifferent carbon precursors (hydrocarbons and carbon monoxide) is consideredthermodynamically. Furthermore, estimation of the maximum length of 1 and 2.5 nmdiameter SWCNTs as a function of carbon solubility is conducted to determine whethercarbon dissolution and precipitation are simultaneous or subsequent process steps.