Hydrocarbon gases (tshwj xeeb tshaj yog methane CH₄ thiab ethylene C₂H₂) muab cov txiaj ntsig zoo ua ntej rau cov pa roj carbon nanotubes (CNTs) hauv cov tshuaj vapor deposition (CVD) txoj kev, feem ntau hauv cov hauv qab no:
1. Cov ntsiab lus carbon siab thiab kev ua haujlwm tawg
- Cov pa roj carbon ntau-rau-hydrogen piv: Gases zoo li methane (CH₄) muaj cov pa roj carbon ntau- rau-hydrogen atomic piv, ua tau zoo tso carbon atoms thaum lub sij hawm pyrolysis, ua rau muaj cov pa roj carbon ntau.
- Qhov kub ntawm qhov kub thiab txias: Hauv CVD txheej txheem (700-1000 degree), hydrocarbon gases tuaj yeem tawg rau ntawm qhov chaw catalyst, ncaj qha tsim carbon atoms rau CNT kev loj hlob nrog ob peb byproducts (tsuas yog hydrogen).
2. Muaj zog txheej txheem Controllability
- Kev tswj tau yooj yim ntawm cov roj ntws thiab cov concentration: Los ntawm kev kho qhov piv ntawm cov pa roj carbon monoxide rau cov pa roj carbon monoxide (piv txwv li, H₂, Ar), cov pa roj carbon ntau tuaj yeem tswj tau qhov tseeb, yog li cuam tshuam rau txoj kab uas hla, cov phab ntsa, thiab kev loj hlob ntawm CNTs.
- Qhov rai loj hlob: Cov pa roj carbon sib txawv (piv txwv li, methane ruaj khov, ethylene yog reactive heev) yog haum rau kev loj hlob ntawm ntau hom CNT (ib zaug-walled/multi-walled).
3. Catalyst Synergistic nyhuv
- Kev txo qis thiab ua kom cov catalysts: Hydrogen atoms tsim los ntawm kev tawg ntawm hydrocarbon gases tswj lub xeev txo ntawm kev hloov cov hlau catalysts (xws li Fe, Co, Ni), tiv thaiv lawv oxidation thiab deactivation.
- Nruab nrab cov pa roj carbon solubility: Supersaturation ntawm carbon nyob rau hauv cov catalyst particles txhawb lub ntsis los yog lub hauv paus loj hlob hom ntawm CNTs.
4. Khoom Purity thiab Zoo
- Ob peb byproducts: Cracking tsuas yog tsim cov pa roj carbon thiab hydrogen gas, txo cov khoom tsis huv xws li amorphous carbon (yog tias qhov sib piv yog tswj kom zoo).
- Tsawg tus qauv tsis xws luag: piv rau cov pa oxygen- muaj cov pa roj carbon monoxide (xws li ethanol), hydrocarbon gases txo qhov tsis xws luag los ntawm oxygen impurities, nyiam kev loj hlob ntawm crystalline CNTs heev.
5. Kev lag luam thiab kev nyab xeeb
- Tus nqi qis: Methane thiab acetylene yog cov khoom lag luam petrochemical, muaj dav, thiab pheej yig heev.
- Kev nyab xeeb tswj tau: Cov pa roj ntws thiab siab tau yooj yim saib xyuas hauv CVD txheej txheem, thiab cov pa hluav taws xob hauv tsev cog khoom qis qis (yog tias methane tawg tag, cov khoom lag luam tseem ceeb yog hydrogen).
6. Daim ntawv thov Adaptability
- Tsim nyog rau kev lag luam loj: Cov khoom siv roj gaseous raw khoom tau yooj yim rau noj tsis tu ncua, ua rau lawv haum rau loj - cov cuab yeej tsim khoom xws li fluidized txaj CVD.
- tuaj yeem siv ua ke nrog lwm cov pa roj: Piv txwv li, ntxiv me me ntawm hydrogen tuaj yeem cuam tshuam cov pa roj carbon amorphous, thiab ntxiv cov pa me me tuaj yeem ntxuav cov catalyst nto ("oxygen-pab" CVD).
