Impact of Thermophoresis on Carbon Nanotube Growth by Chemical Vapor Deposition

Thermophoretic effect on the growth of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) has been investigated using a fully coupled gas-phase and surface chemistry model. This reactor-scale model employs conservation of mass, momentum, species, and energy equations to describe the evolution of hydrogen and hydrocarbon feed streams as they undergo thermal transport and chemical reactions within the CVD reactor. The resulting CNT growth rates on individual catalytic iron nanoparticles located on the reactor wall is predicted by the model as well as steady state velocity, temperature, and concentration fields within the reactor volume and concentrations of species adsorbed onto the nanoparticle surfaces. The effect of thermophoresis on volumetric concentration fields and surface species adsorption for deposition occurring in differing reactor boundary and flow conditions has been investigated to understand the impacts on CNT growth. This investigation is useful in order to optimize reactor design and boundary conditions to promote optimal CNT deposition rates.