Method for synthesizing high-purity carbon nanocoils based on composite catalyst formed by multiple small-sized catalyst particles

A method for synthesizing high-purity carbon nanocoils based on a composite catalyst formed by multiple small-sized catalyst particles, wherein the method first prepares Fe—Sn—O nanoparticles with a size of less than 100 nm, uses the nanoparticles as a catalyst, and then uses the prepared catalyst to efficiently synthesize carbon nanocoils by method of thermal chemical vapor deposition (CVD), comprising the following steps:

• (1) preparing small-sized catalysts for growth of the carbon nanocoils
• using a Fe3+ salt or a ferric oxide and a soluble Sn4+ salt or a tin oxide as raw materials, and using chemical synthesis methods, physical methods or a combination thereof to prepare composite catalyst powder, wherein the composite catalyst powder is composed of Fe—Sn—O, the molar ratio of Fe to Sn in the catalyst is 5:1-30:1, and the particle size of the catalyst is 10 to 100 nm;
• (2) efficiently catalyzing the growth of carbon nanocoils with the synthesized composite catalyst by adopting CVD method
• dispersing the prepared composite catalyst powder in a solvent such as water or ethanol, where the concentration of the dispersion liquid is 0.01 to 1 mg/ml, and cleaning the substrate;
• drop-coating, spin-coating or spray-coating the catalyst dispersion liquid onto the surface of the substrate, wherein the density range of the catalyst on the surface of the substrate is 1×109/cm−2 to 5×1010/cm−2, and realizing uniform support and mutual accumulation and contact of catalyst particles on the substrate;
• and putting the dried substrate in a CVD system, and synthesizing the high-purity carbon nanocoils by CVD, wherein the purity of the carbon nanocoils is larger than 95%.