Advanced materials from natural materials: Synthesis of aligned carbon nanotubes on wollastonites

The growth of carbon nanotubes (CNTs) on natural materials is a low-cost, environmentally benign, and materials-saving method for the large-scale production of CNTs. Directly building 3D CNT architectures on natural materials is a key issue for obtaining advanced materials with high added value. We report the fabrication of aligned CNT arrays on fibrous natural wollastonite. Strongly dispersed iron particles with small sizes were produced on a planar surface of soaked fibrous wollastonite by a reduction process. These particles then catalyzed the decomposition of ethylene, leading to the synchronous growth of CNTs to form leaf-and brush-like wollastonite/CNT hybrids. The as-obtained hybrids could be further transformed into porous SiO₂/CNT hybrids by reaction with hydrochloric acid. Further treatment with hydrofluoric acid resulted in aligned CNT arrays, with purities as high as 98.7%. The presented work is very promising for the fabrication of advanced materials with unique structures and properties that can be used as fillers, catalyst supports, or energy-absorbing materials.