{ "id": "epfa6h38w5", "slug": "floating-catalyst-chemical-vapor-deposition", "title": "Floating catalyst chemical vapor deposition", "updated": "2026-10-25", "topic_path": [ { "id": "physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/topics/physical" }, { "id": "physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry" }, { "id": "physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods" }, { "id": "physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.chemical-synthesis" } ], "geo": [ { "id": "geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis", "label": "Non-geographic · 1946 to 2000: Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t1946", "label": "Non-geographic · 1946 to 2000", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946" }, { "id": "geo.nongeo.t1946.physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical" }, { "id": "geo.nongeo.t1946.physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry" }, { "id": "geo.nongeo.t1946.physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry.methods" }, { "id": "geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis", "label": "Chemical synthesis", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t1946.physical.chemistry.methods.chemical-synthesis" } ] } ], "excerpt": "Floating catalyst chemical vapor deposition (FCCVD, also called aerosol CVD) is a technique where catalyst nanoparticles float in the gas stream, so carbon nanotubes grow airborne and are collected continuously as films, yarns, and aerogels.", "snippet": "Floating catalyst chemical vapor deposition (FCCVD, also called aerosol CVD) is a technique where catalyst nanoparticles float in the gas stream, so carbon nanotubes grow airborne and are collected continuously as films, yarns, and aerogels.", "node": "physical.chemistry.methods.chemical-synthesis", "markdown": "# Floating catalyst chemical vapor deposition\n\nFloating catalyst chemical vapor deposition (FCCVD, also called aerosol CVD or FC-CVD) is a chemical vapor deposition technique in which catalytic nanoparticles are formed and carried in the gas stream rather than fixed on a substrate, so carbon nanotubes nucleate and grow while airborne and can be collected continuously as films, aerogels (ultra-light solid from gel with liquid replaced by gas), yarns, and sheets. Because the catalyst is formed and carried in the gas phase rather than immobilized on a growth substrate, the process runs in a single continuous step from precursor decomposition through nanotube growth, which makes it scalable and lets the growing nanotubes self-assemble directly into freestanding materials.[1](https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr00289f) • [2](https://pubs.acs.org/jpccck/article-pdf/127/49/23577/2864756/jp3c05777.pdf) Growth in the floating mode is fast, reported at \\( 10^{7} \\)–\\( 10^{8} \\) atoms per second, up to 1000 times faster than substrate CVD, and the resulting nanotubes are longer and of higher quality than those from fluidized- or packed-bed methane pyrolysis reactors, according to Adam Boies, a synthesis engineer at Stanford University who led recent multi-pass reactor research.[1](https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr00289f) • [3](https://cen.acs.org/synthesis/process-chemistry/chemical-reactor-carbon-nanotube-hydrogen-catalyst/103/web/2025/12)\n\n| Key fact | Value |\n|---|---|\n| Peak reactor temperature (one modeling study) | 1150–1300 °C[4](https://www.mdpi.com/2073-4344/10/12/1383) |\n| Standard feed | Hydrogen carrier, methane (~20% of mass), ferrocene (0.5%), thiophene (3%)[4](https://www.mdpi.com/2073-4344/10/12/1383) |\n| Catalyst nanoparticle size for growth | One to few nanometers[5](https://www.sciencedirect.com/science/article/abs/pii/S0008622325002751) |\n| Growth rate (in situ, high-temperature reactor) | 250 μm/s mean, lengths 0.1–54 μm[6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) |\n| Direct fiber extraction yield | Greater than 3 g per day of few-walled CNTs[7](https://www.sciencedirect.com/science/article/abs/pii/S1385894720304885) |\n| Water-assisted forest purity | Above 99.98% carbon purity, heights up to 2.5 mm[6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) |\n| Multi-pass gas recycling | ~99 vol% of process gas recirculated; effluent 84.7 vol% \\( H_{2} \\)[8](https://www.nature.com/articles/s41560-025-01925-3) |\n\n## How it works\n\nThe reactor working fluid carries a carbon source, an iron source, and a sulfur source in a carrier gas. On heating, the iron source decomposes into iron vapor, which nucleates into iron nanoparticles that remain suspended in the flow and serve as the floating catalyst; sulfur promotes this growth.[4](https://www.mdpi.com/2073-4344/10/12/1383) In a methane-fed multi-pass reactor, the precursors are heated to about 1300 °C, where methane pyrolyzes to hydrogen and C2 species, primarily acetylene and ethylene, in the presence of nucleating iron–sulfur nanoparticles.[8](https://www.nature.com/articles/s41560-025-01925-3) The commonly accepted simplified mechanism holds that nanotube growth occurs when catalyst nanoparticles of the correct size, one to few nanometers, are formed and other conditions are satisfied simultaneously.[5](https://www.sciencedirect.com/science/article/abs/pii/S0008622325002751) [Ferrocene](https://www.edgepedia.org/ferrocene) is an effective precursor for direct synthesis of high-quality single-walled nanotubes, and the formation of the iron floating catalyst involves initial competing chemical pathways that remain under study.[9](https://pubs.aip.org/aip/jap/article/129/4/044302/1079004/Initial-competing-chemical-pathways-during) Aerogel formation requires a catalyst, typically iron, and a promotor, typically sulfur; one study reinterprets their synergistic roles through sulfur-driven catalyst nucleation and a critical catalyst particle [mass concentration](https://www.edgepedia.org/mass-concentration).[10](https://www.nature.com/articles/s41598-017-14775-1)\n\nTemperature is central to the rate. [In situ](https://www.edgepedia.org/in-situ) measurements attribute the exceptionally high FCCVD growth rates to uniquely high reactor temperatures above 1500 K, and the CNT-containing particle number density increases more than 10-fold as the flow travels through a zone of rising temperature.[6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) Published peak-temperature ranges differ: one modeling study gives 1150–1300 °C,[4](https://www.mdpi.com/2073-4344/10/12/1383) while the in situ study attributes its results to temperatures above 1500 K (about 1230 °C and above); the sources do not settle a single canonical range.[6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) Hydrogen carrier gas generates a reducing atmosphere, facilitates carbon source decomposition, and prevents formation of amorphous carbon or soot, but synthesis yield decreases as hydrogen flow increases.[2](https://pubs.acs.org/jpccck/article-pdf/127/49/23577/2864756/jp3c05777.pdf)\n\n## How it is done\n\nA standard run injects a liquid or gaseous feed into a heated tube reactor. In one documented water-assisted recipe, the catalyst solution contains ferrocene and thiophene at an Fe:S molar ratio of 1:3, acetone as the carbon source, and 0–2 mL of de-ionized water; it is injected at 5–25 mL/h into an alumina tube reactor at 1250 °C with argon at 700–1200 sccm and hydrogen at 50–400 sccm.[11](https://www.mdpi.com/2079-4991/10/2/365) Gaseous carbon sources in use include carbon monoxide, ethylene, and methane; ethanol and toluene are common liquid sources.[2](https://pubs.acs.org/jpccck/article-pdf/127/49/23577/2864756/jp3c05777.pdf) In a CO-based aerosol CVD reactor operating at ambient pressure with an 880 °C hot zone, ferrocene vapor is carried by CO and mixed with an additional CO flow introduced through a thin injector probe tube (4 mm inner diameter) into the hot zone.[12](https://nanonasibulin.com/wp-content/uploads/sites/21/2023/04/Khabushev-activation.pdf)\n\nThe airborne nanotubes are collected continuously: the FCCVD process can wind the CNT aerogel directly into product forms such as yarns and sheets, giving mass production potential.[11](https://www.mdpi.com/2079-4991/10/2/365) Direct fiber extraction from the reactor has delivered yields greater than 3 g per day of nearly uniform few-walled nanotubes under published recipe conditions.[7](https://www.sciencedirect.com/science/article/abs/pii/S1385894720304885)\n\n## Origin\n\nThe FC-CVD process continuously produces carbon nanotubes in a heated reactor.[4](https://www.mdpi.com/2073-4344/10/12/1383) The aerosol (floating catalyst) CVD method is described as one of the most promising CNT synthesis approaches because of significant technological advantages: scalability, continuous operation mode, robust material handling, dry-transfer thin films, and direct deposition onto substrates.[12](https://nanonasibulin.com/wp-content/uploads/sites/21/2023/04/Khabushev-activation.pdf) The historical origins of the method, including the earlier fixed-catalyst approaches it displaced, are not documented in this article's cited sources.\n\n## Variants\n\nSeveral named variants modify the carrier gas, injection geometry, or chemistry. Water-assisted FCCVD adds de-ionized water to the catalyst system; it shifted production from multi-walled to double-walled nanotubes, with diameters decreasing from 19–23 nm to 10–15 nm and a Raman \\( I_{\\mathrm{G}}/I_{\\mathrm{D}} \\) ratio up to 10.23.[11](https://www.mdpi.com/2079-4991/10/2/365) Water acts as a weak oxidizer that selectively removes amorphous carbon without damaging the CNT network; catalyst deactivation occurs by carbon coating, and water removes this coating to revive catalyst activity, an effect verified by \"Ball-CVD\" and exploited by water-assisted \"super growth\" of vertically aligned SWCNT forests with purity above 99.98%. In a separate gas-flow-directed water-assisted CVD study, adding 0.43% water increased the average growth rate of 10–20 cm long nanotubes from 20 to 80–90 μm/s.[11](https://www.mdpi.com/2079-4991/10/2/365) • [6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) Deep-injection FCCVD (DI-FCCVD) sends the feed through a colder jet that penetrates deep into the reactor, creating axial recirculation near the walls; a heavier inert gas such as argon plays critical roles in simultaneously improving crystallinity and productivity of CNTs and CNT fibers.[5](https://www.sciencedirect.com/science/article/abs/pii/S0008622325002751) An open-atmosphere variant uses nitrogen as the sole carrier gas, eliminating both the hydrogen carrier and the inert-purged harvest box required by traditional FC-CVD; methanol was chosen as feedstock because at high temperature it forms CO and \\( H_{2} \\) rather than solid carbon, preventing soot.[13](https://link.springer.com/article/10.1007/s42823-024-00843-w) Reactor geometry is also a variant axis: a 100 mm large-diameter reactor was built to resolve scalability and continuous sheet formation limits,[14](https://pubs.rsc.org/en/content/articlelanding/2026/qm/d5qm00836k) and a multi-pass reactor recycles about 99 vol% of process gas through the hot zone in a quasi-closed loop, co-producing turquoise hydrogen and CNT mats without exogenous hydrogen during steady-state operation, and it works with pure methane and with methane contaminated with 33 vol% CO₂, simulating unrefined bioderived methane such as biogas or landfill gas.[8](https://www.nature.com/articles/s41560-025-01925-3) Vertically aligned nanotubes are harder to reach in this family: two-stage or higher CVD configurations are often used to produce VACNTs, but their adaptation in FC-CVD systems is significantly hindered, and FC-CVD typically uses ferrocene-derived Fe⁰ nanoparticles with camphor, toluene, or acetylene as carbon sources.[15](https://link.springer.com/article/10.1186/s13065-025-01460-y)\n\n## Applications\n\nThe route continuously transforms gas precursors into aerosols, then aerogels, then macroscopic nanotextiles, and has produced high-performance structural materials, transparent conductors, and battery anodes; bulk properties depend strongly on inter-particle properties and are dominated by alignment and volume fraction.[1](https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr00289f) The process yields high-quality CNTs suitable for macroscopic materials including direct-spun and solution-processed fibers, films, and foams,[5](https://www.sciencedirect.com/science/article/abs/pii/S0008622325002751) and aerosol CVD thin films show high electrical conductivity that attracts academic and industrial interest.[16](https://pubmed.ncbi.nlm.nih.gov/39811988/) Material quality examples include CNT/BMI composites from water-assisted FCCVD material with 1720 S/cm conductivity along the bundle alignment direction and an axial reduced modulus of 65 GPa,[11](https://www.mdpi.com/2079-4991/10/2/365) and open-atmosphere spun fibers at 240 ± 24 S/cm with a low \\( I_{\\mathrm{D}}/I_{\\mathrm{G}} \\) ratio indicating high crystallinity.[13](https://link.springer.com/article/10.1007/s42823-024-00843-w) For industrial context, manufacturers currently use methane pyrolysis to produce tens of thousands of metric tons of CNTs per year, mostly in fluidized- or packed-bed reactors; FCCVD's gas-phase catalyst route produces longer, higher-quality nanotubes better suited to electrodes and polymer composites.[3](https://cen.acs.org/synthesis/process-chemistry/chemical-reactor-carbon-nanotube-hydrogen-catalyst/103/web/2025/12)\n\n## Limitations and alternatives\n\nA low catalyst activation degree, the fraction of catalyst nanoparticles that nucleate nanotubes and contribute to SWCNT growth, is a main drawback hampering SWCNT mass production; ferrocene thermal decomposition is the in situ catalyst formation route, contrasted with ex situ delivery by a spark discharge generator.[12](https://nanonasibulin.com/wp-content/uploads/sites/21/2023/04/Khabushev-activation.pdf) Catalyst deactivation by carbon coating is the failure mode that water injection addresses.[6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) [Productivity](https://www.edgepedia.org/productivity) is not simply temperature-controlled: the rate of CNT mass production within the reactor does not vary monotonically with temperature, suggesting that changing catalyst activity governs overall production.[6](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449) [Transport phenomena](https://www.edgepedia.org/transport-phenomena) also limit output, as the deep-injection study's flow-pattern and hydrogen-chemistry productivity losses show.[5](https://www.sciencedirect.com/science/article/abs/pii/S0008622325002751) Against supported-catalyst CVD, FCCVD trades substrate-bound control (for example, vertically aligned forests) for continuous, single-step operation and direct assembly into freestanding materials.[1](https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr00289f) • [15](https://link.springer.com/article/10.1186/s13065-025-01460-y) Quantitative comparisons with arc discharge and laser ablation are not settled in the published literature; only qualitative statements about CVD displacing the high-temperature techniques are available.\n\n## References\n\n1. [Gas-to-nanotextile: high-performance materials from floating 1D nanoparticles (Nanoscale, 2023)](https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr00289f)\n2. [FCCVD synthesis of Fe-SWCNTs: effect of hydrogen concentration (J. Phys. Chem. C)](https://pubs.acs.org/jpccck/article-pdf/127/49/23577/2864756/jp3c05777.pdf)\n3. [Gas looping boosts efficiency of carbon nanotube production (C&EN, December 2025)](https://cen.acs.org/synthesis/process-chemistry/chemical-reactor-carbon-nanotube-hydrogen-catalyst/103/web/2025/12)\n4. [Flow Simulations Including Iron Nanoparticle Nucleation, Growth and Evaporation for Floating Catalyst CNT Production (Catalysts, 2020)](https://www.mdpi.com/2073-4344/10/12/1383)\n5. [Understanding the effect of transport phenomena in deep-injection floating catalyst chemical vapor deposition carbon nanotube synthesis (Carbon, 2025)](https://www.sciencedirect.com/science/article/abs/pii/S0008622325002751)\n6. [Measurement of High Carbon Nanotube Growth Rate, Mass Production, Agglomeration, and Length in a Floating Catalyst Chemical Vapor Deposition Reactor](https://pubs.acs.org/doi/full/10.1021/acsnano.4c15449)\n7. [Forecasting continuous carbon nanotube production in the floating catalyst environment (Chemical Engineering Journal, 2020)](https://www.sciencedirect.com/science/article/abs/pii/S1385894720304885)\n8. [Production of hydrogen and carbon nanotubes from methane using a multi-pass floating catalyst chemical vapour deposition reactor with process gas recycling](https://www.nature.com/articles/s41560-025-01925-3)\n9. [Initial competing chemical pathways during floating catalyst chemical vapor deposition carbon nanotube growth (Journal of Applied Physics)](https://pubs.aip.org/aip/jap/article/129/4/044302/1079004/Initial-competing-chemical-pathways-during)\n10. [The Dependence of CNT Aerogel Synthesis on Sulfur-driven Catalyst Nucleation Processes and a Critical Catalyst Particle Mass Concentration (Scientific Reports, 2017)](https://www.nature.com/articles/s41598-017-14775-1)\n11. [Continuous Synthesis of Double-Walled Carbon Nanotubes with Water-Assisted Floating Catalyst Chemical Vapor Deposition (Nanomaterials, 2020)](https://www.mdpi.com/2079-4991/10/2/365)\n12. [Activation of Catalyst Particles for Single-walled Carbon Nanotube Synthesis (Khabushev et al.)](https://nanonasibulin.com/wp-content/uploads/sites/21/2023/04/Khabushev-activation.pdf)\n13. [Open-atmosphere spinning of carbon nanotube fibers sans hydrogen flow by floating catalyst chemical vapor deposition (Carbon Letters, 2024)](https://link.springer.com/article/10.1007/s42823-024-00843-w)\n14. [A large-diameter FCCVD reactor approach for scalable CNT sheet fabrication (Materials Chemistry Frontiers)](https://pubs.rsc.org/en/content/articlelanding/2026/qm/d5qm00836k)\n15. [A novel fabrication method of vertically aligned carbon nanotubes by single-stage floating catalyst CVD (BMC Chemistry, 2025)](https://link.springer.com/article/10.1186/s13065-025-01460-y)\n16. [Aerosol CVD Carbon Nanotube Thin Films: From Synthesis to Advanced Applications: A Comprehensive Review (2025)](https://pubmed.ncbi.nlm.nih.gov/39811988/)\n\n---\n*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Chemical principles and methods › Chemical synthesis*\n\n*Initially written Sep 29, 2026 · Edited: Oct 15, 2026; Oct 21, 2026; Oct 25, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition", "markdown_url": "https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Floating catalyst chemical vapor deposition\", Edgepedia (EdgeChat), https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition. Edgepedia Community License 1.0.", "credit_md": "\"[Floating catalyst chemical vapor deposition](https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition](https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Floating catalyst chemical vapor deposition\", Edgepedia (EdgeChat), https://www.edgepedia.org/floating-catalyst-chemical-vapor-deposition. Edgepedia Community License 1.0.", "speakable": "Floating catalyst chemical vapor deposition is a technique where catalyst nanoparticles float in the gas stream, so carbon nanotubes grow airborne and are collected continuously as films, yarns, and aerogels." }