Systems and methods are provided for production of carbon nanotubes and H.sub.2 using a reaction system configuration that is suitable for large scale production. In the reaction system, a substantial portion of the heat for the reaction can be provided by using a heated gas stream. Optionally, the heated gas stream can correspond to a heated H.sub.2 gas stream. By using a heated gas stream, when the catalyst precursors for the floating catalyst-chemical vapor deposition (FC-CVD) type catalyst are added to the gas stream, the gas stream can be at a temperature of 1000° C. or more. This can reduce or minimize loss of catalyst precursor material and/or deposition of coke on sidewalls of the reactor. Additionally, a downstream portion of the reactor can include a plurality of flow channels of reduced size that are passed through a heat exchanger environment, such as a shell and tube heat exchanger. This can provide cooling of the gas flow after catalyst formation to allow for carbon nanotube formation, while also reducing the Reynolds number of the flow sufficiently to provide laminar flow within the region where carbon nanotubes are formed.

Systems and methods are provided for production of carbon nanotubes and H.sub.2 using a reaction system configuration that is suitable for large scale production. In the reaction system, a substantial portion of the heat for the reaction can be provided by using a heated gas stream. Optionally, the heated gas stream can correspond to a heated H.sub.2 gas stream. By using a heated gas stream, when the catalyst precursors for the floating catalyst-chemical vapor deposition (FC-CVD) type catalyst are added to the gas stream, the gas stream can be at a temperature of 1000° C. or more. This can reduce or minimize loss of catalyst precursor material and/or deposition of coke on sidewalls of the reactor. Additionally, a downstream portion of the reactor can include a plurality of flow channels of reduced size that are passed through a heat exchanger environment, such as a shell and tube heat exchanger. This can provide cooling of the gas flow after catalyst formation to allow for carbon nanotube formation, while also reducing the Reynolds number of the flow sufficiently to provide laminar flow within the region where carbon nanotubes are formed.

The embodiments of the present disclosure relate to a method and apparatus for producing a carbon nanomaterial product (CNM) product that may comprise carbon nanotubes and various other allotropes of nanocarbon. The method and apparatus employ a consumable carbon dioxide (CO.sub.2) and a renewable carbonate electrolyte as reactants in an electrolysis reaction in order to make CNTs. In some embodiments of the present disclosure, operational conditions of the electrolysis reaction may be varied in order to produce the CNM product with a greater incidence of a desired allotrope of nanocarbon or a desired combination of two or more allotropes.

A method of making carbon nanotubes is provided, the method includes depositing a catalyst layer on a substrate, placing the substrate having the catalyst layer in a reaction furnace, heating the reaction furnace to a predetermined temperature, introducing a carbon source gas and a protective gas into the reaction furnace to grow a first carbon nanotube segment structure comprising a plurality of metallic carbon nanotube segments, and applying a pulsed electric field to grow a second carbon nanotube segment structure from the plurality of metallic carbon nanotube segments, where the pulsed electric field is a periodic electric field including a plurality of positive electric field pulses and a plurality of negative electric field pulses alternately arranged, and the second carbon nanotube segment structure includes a plurality of semiconducting carbon nanotube segments.

A method of making carbon nanotubes is provided, the method includes depositing a catalyst layer on a substrate, placing the substrate having the catalyst layer in a reaction furnace, heating the reaction furnace to a predetermined temperature, introducing a carbon source gas and a protective gas into the reaction furnace to grow a first carbon nanotube segment structure comprising a plurality of metallic carbon nanotube segments, and applying a pulsed electric field to grow a second carbon nanotube segment structure from the plurality of metallic carbon nanotube segments, where the pulsed electric field is a periodic electric field including a plurality of positive electric field pulses and a plurality of negative electric field pulses alternately arranged, and the second carbon nanotube segment structure includes a plurality of semiconducting carbon nanotube segments.

A carbon nanotube (CNT) hybrid material that includes a blend comprising a catalyst supported on at least one of a metal, metalloid, metal oxide or carbon support, and at least one material selected from the group of materials consisting of: cementitious materials, materials used in the production of cementitious materials, and materials used to enhance cementitious materials, and CNT on the blend.

A carbon nanotube (CNT) hybrid material that includes a blend comprising a catalyst supported on at least one of a metal, metalloid, metal oxide or carbon support, and at least one material selected from the group of materials consisting of: cementitious materials, materials used in the production of cementitious materials, and materials used to enhance cementitious materials, and CNT on the blend.

Provided is a method of producing a catalyst-bearing support that produces a catalyst-bearing support used in production of a fibrous carbon nanostructure. The production method includes: a stirring step of rotating an approximately circular tube-shaped rotary drum around a central axis so as to stir a particulate support; a spraying step of spraying a catalyst solution against the particulate support inside of the rotary drum; and a drying step causing a drying gas to flow to inside of the rotary drum from outside of the rotary drum so as to dry catalyst solution attached to the particulate support. In this production method, at least part of an implementation period of the stirring step and at least part of an implementation period of the spraying step overlap with each other.

Provided is a method of producing a catalyst-bearing support that produces a catalyst-bearing support used in production of a fibrous carbon nanostructure. The production method includes: a stirring step of rotating an approximately circular tube-shaped rotary drum around a central axis so as to stir a particulate support; a spraying step of spraying a catalyst solution against the particulate support inside of the rotary drum; and a drying step causing a drying gas to flow to inside of the rotary drum from outside of the rotary drum so as to dry catalyst solution attached to the particulate support. In this production method, at least part of an implementation period of the stirring step and at least part of an implementation period of the spraying step overlap with each other.

A method of fabricating a carbon nanotube (“CNT”) array includes providing a substrate with a CNT catalyst disposed on a surface of the substrate, heating the CNT catalyst to an annealing temperature, exposing the CNT catalyst to a CNT precursor for an exposure period to pre-load the CNT catalyst, and exposing the pre-loaded CNT catalyst to a carbon source for a growth period to form the CNT array. The formed CNT array comprises a plurality of CNT bundles that are aligned with one another in an alignment direction. At least one of the plurality of bundles comprises an average structural factor of 1.5 or less along an entirety of the length thereof.