I am trying to grow very small diameter single wall carbon nanotubes that are less than 1nm in diameter length. Any suggestions for acquiring a consistent particle size catalyst?
the preparation of a catalyst having a specific particle diameter with high catalytic activity, high selectivity, and good dispersibility is the key to whether the CVD method can mass produce high-purity CNTs. The catalysts prepared by different methods have different dispersibilities and large difference in catalytic activity, which results in different carbon nanotube content and tube diameter. The composite catalyst prepared by the same method has a closely related relationship between the catalytic activity and the ratio of the effective component and the carrier, and the optimum ratio.
Some popular transition metal nanoparticles are usually used as catalysts in CVD synthesis of CNTs [54]. It is reported that Fe, Co, Ni, Pd, Pt, Au, Mn, W, Ti, Co, Mg, Al, In, Na, K, Cs, and other metals reported can be used in the preparation of MWCNT in recent years, and the diameter of these catalyst nanoparticles is usually larger than 3 nm. Single-walled CNTs are usually produced when the active components of Fe, Co, Ni, Pd, Pt, Ru, Cu, Ag, Au, Mn, Cr, Mo, and other metals act as catalysts, and the particle size of the generated nanoparticles is often less than 3 nm.
Due to the high carbon solubility of Fe, Co, and Ni, transition metal carbides can be formed. With a high diffusion rate in these transition metals, nucleation and growth of carbon atoms can be carried out . Cu, Au, Ag, Pt, and Pd can also be used to synthesize CNTs by catalyzing appropriate carbon sources
The Maruyama´s procedure is very efficient. It starts with molybdenum acetate in ethanol (I don't remember the concentration). The substrate is immersed in this solution for a few seconds and then calcined at 400 °C in air for 20 minutes. The substrate is then re-immersed in another solution of cobalt acetate in ethanol for a few seconds and calcined again at 400 °C in air for 20 minutes. After this process, Mo and Co are in the form of oxides. During the growth of SWNTs (using ethanol in nitrogen, as a carbon source), the hydrogen present in the reaction mixture together with the temperature, causes the reduction of the oxides of Co and Mo, together with the catalytic growth of single-walled nanotubes of approx. 1 nm in diameter.
The best idea on the researcher can identify the crystallite size of catalyst via XRD, and BET (determine of surface area). From characterize the catalyst you may know the capability of catalyst.
The simple method to prepare catalyst via using wet impregnation method. The metal catalyst was impregnated on the supports like alumina etc.
One of the factor you need to consider is your carbon source.
Mohd Syazwan excellent suggestion. I am actually working on something like that currently. The surface of the catalyst and the type of the catalyst seem to be a key determinant in the growth of specific single wall carbon nanotubes with certain characteristics. The amount of carbon deposited on the substrate also determines the type of carbon nanotubes made (multiwall, single wall, double wall, etc).
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