Selective synthesis of carbon nanomaterials of different structures over KNO₃ catalyst

We described a simple route for the generation of pure carbon nanomaterials (CNMs). In the decomposition of acetylene at different temperatures over KNO₃ particles, helical carbon nanofibers (HCNFs) and CNFs of low helicity (L-CNFs) are synthesized with high selectivity through the control of pyrolysis temperature. It is found that the size of KNO₃ particles is a decisive factor for the growth of CNMs. Since KNO₃ is water-soluble, it can be easily removed from the as-synthesized products through steps of water washing, and CNMs can be obtained undamaged in high purity. The approach is simple, inexpensive and environment-benign, and can be adopted for the selective production of high-purity CNMs.