Size-selective catalytic growth of nearly 100% pure carbon nanocoils with copper nanoparticles produced by atomic layer deposition.

In this paper, Cu nanoparticles with narrow size distribution are synthesized by reduction of CuO films produced by atomic layer deposition (ALD), which are used as catalysts for the catalytic growth of carbon nanostructures. By properly adjusting the ALD cycle numbers, the size of produced Cu nanoparticles can be well controlled. Uniform carbon nanocoils with near 100% purity can be obtained by using 50-80 nm Cu nanoparticles, while thin straight fibers and thick straight fibers are produced by applying 5-35 and 100-200 nm Cu nanoparticles, respectively. The mechanism of the particle size-dependent growth of the carbon nanostructure was analyzed based on the experimental results and theoretical simulation. Our results can provide important information for the preparation of helical carbon nanostructures with high purity. Moreover, this work also demonstrates that ALD is a viable technique for synthesizing nanoparticles with highly controllable size and narrow size distribution suitable for studying particle size-dependent catalytic behavior and other applications.