Method and device for producing carbon nanotubes

Abstract

Methods and devices for producing carbon nanotubes are disclosed herein. These methods and devices are based on chemical vapor deposition (CVD) in an open environment under atmospheric pressure, which eliminates the need for a vacuum chamber or evacuation process to remove oxygen and/or impurities prior to carbon nanotube growth.

1 . A device for producing carbon nanotubes, the device comprising:
 a fluid delivery portion comprising a carbon-containing precursor reservoir, a reducing agent reservoir, and an inert gas reservoir;   a coaxial jet reactor in fluid communication with the fluid delivery portion, wherein the coaxial jet reactor comprises an outer nozzle configured to receive an inert gas and an inner nozzle configured to receive a carbon-containing precursor and a reducing agent;   a deposition portion in fluid communication with the coaxial jet reactor, wherein the deposition portion comprises an outer zone configured to receive the inert gas from the outer nozzle, an inner zone configured to receive the carbon-containing precursor and reducing agent from the inner nozzle, and a substrate having at least a portion within the inner zone, wherein the outer zone, inner zone and the substrate are in an open environment; and   a heating source configured to heat the at least the portion of the substrate within the inner zone effective to thermally decompose at least a portion of the carbon-containing precursor in the presence of the reducing agent and produce the carbon nanotubes on the substrate.   
     
     
         2 . The device of  claim 1 , wherein the fluid delivery portion further comprises a mixer, a mass flow controller, or both, wherein the mixer is at a junction upstream of the inner nozzle of the coaxial jet reactor and downstream of the carbon-containing precursor reservoir and the reducing agent reservoir, and wherein the mass flow controller configured to regulate an amount of fluid dispensed by the carbon-containing precursor reservoir, reducing agent reservoir, or inert gas reservoir. 
     
     
         3 . The device of  claim 1 , wherein a ratio of a thickness of the outer zone of the coaxial jet reactor to the inner zone of the coaxial jet reactor is greater than or equal to about 0.1:1. 
     
     
         4 . The device of  claim 1 , wherein the deposition portion further comprises an exhaust, a scattered light absorber, or both. 
     
     
         5 . The device of  claim 1 , wherein the heating source is a laser. 
     
     
         6 . The device of  claim 1 , further comprising an optical lens, an aligning laser, a laser diode, a beam splitter, a mirror, a temperature-sensing device, or a combination comprising at least one of the foregoing. 
     
     
         7 . The device of  claim 1 , further comprising a controller in operative communication with the heating source, mass flow controller, mixer, optical lens, aligning laser, laser diode, beam splitter, mirror, temperature sensing device, substrate, or a combination comprising at least one of the foregoing. 
     
     
         8 . The device of  claim 1 , wherein the substrate is a moving substrate. 
     
     
         9 . The device of  claim 1 , wherein a surface of the substrate comprises a nanotube growing catalyst. 
     
     
         10 . The device of  claim 1 , wherein a volumetric ratio of the carbon-containing precursor to the reducing agent is about 0.01:1 to about 15:1. 
     
     
         11 . The device of  claim 1 , wherein a volumetric ratio of the carbon-containing precursor and the reducing agent to the inert gas is about 0.001:1 to about 10:1. 
     
     
         12 . A device for producing carbon nanotubes, the device comprising:
 a fluid delivery portion comprising a carbon-containing precursor reservoir, a reducing agent reservoir, an inert gas reservoir, a carbon-containing precursor mass flow controller, a reducing agent mass flow controller, an inert gas mass flow controller, and a mixer at a junction downstream of the carbon-containing precursor reservoir and the reducing agent reservoir, and   a coaxial jet reactor in fluid communication with the fluid delivery portion, wherein the coaxial jet reactor comprises an outer nozzle configured to receive an inert gas and an inner nozzle configured to receive a carbon-containing precursor and a reducing agent;   a deposition portion in fluid communication with the coaxial jet reactor, wherein the deposition portion comprises an outer zone configured to receive the inert gas from the outer nozzle, an inner zone configured to receive the carbon-containing precursor and reducing agent from the inner nozzle, a substrate having at least a portion within the inner zone, a nanotube growing catalyst disposed on a surface of the substrate, an exhaust, and a scattered light absorber, wherein the outer zone, inner zone, substrate, nanotube growing catalyst exhaust, and scattered light absorber are in an open environment;   a laser, wherein a beam produced by the laser is configured to heat the at least the portion of the substrate within the inner zone effective to thermally decompose at least a portion of the carbon-containing precursor in the presence of the reducing agent and produce the carbon nanotubes on the substrate; and   a controller in operative communication with the laser, carbon-containing precursor mass flow controller, reducing agent mass flow controller, inert gas mass flow controller, mixer, substrate or a combination comprising at least one of the foregoing.   
     
     
         13 . The device of  claim 12 , wherein a ratio of a thickness of the outer zone of the coaxial jet reactor to the inner zone of the coaxial jet reactor is greater than or equal to about 0.1:1. 
     
     
         14 . The device of  claim 12 , further comprising an optical lens, an aligning laser, a laser diode, a beam splitter, a mirror, a temperature-sensing device, or a combination comprising at least one of the foregoing. 
     
     
         15 . The device of  claim 14 , wherein the controller is further in operative communication with the optical lens, aligning laser, laser diode, beam splitter, mirror, temperature sensing device, or a combination comprising at least one of the foregoing. 
     
     
         16 . The device of  claim 12 , wherein the substrate is a moving substrate. 
     
     
         17 . A method for growing carbon nanotubes, comprising:
 heating at least a portion of a substrate in an open environment;   forming a first jet of reactants comprising a carbon-containing precursor and a reducing agent, wherein the first jet is surrounded by a second jet of inert gas that is effective to protect the reactants from the open environment;   thermally decomposing at least a portion of the carbon-containing precursor in the presence of the reducing agent in proximity to the heated substrate; and   growing the carbon nanotubes on the at least the portion of the substrate.   
     
     
         18 . The method of  claim 17 , further comprising mixing the carbon-containing precursor with the reducing agent prior to the forming the jet of reactants in an open environment. 
     
     
         19 . The method of  claim 17 , further comprising disposing a nanotube growing catalyst onto the at least a portion of a substrate. 
     
     
         20 . The method of  claim 17 , further comprising moving the substrate contemporaneously with the growing.