Catalysts for chirality selective synthesis of single-walled carbon nanotubes

The chiral structures of single-walled carbon nanotubes (SWCNTs) can greatly affect their electronic, optical, thermal, mechanical and magnetic properties. As such, it has been a long-standing goal to selectively synthesize single chirality SWCNTs for potential applications ranging from electronics to medicine. Catalytic chemical vapor deposition is the prevalent method for chirality selective synthesis of SWCNTs. In this method, the catalyst plays a critical role in the chirality selection. This review summarizes the up-to-date catalyst development for chirality selective synthesis of SWCNTs, and discusses the general principles in current state-of-the-art catalyst designs. Metal catalysts, which account for the majority of catalysts used so far, are first reviewed. They are divided into supported catalysts on porous and flat substrates and unsupported catalysts. The discussion is focused on catalyst preparation methods, which determine the performance of catalysts. Next, non-metal catalysts are examined. New approaches of using carbon seeds for SWCNT “cloning” are also summarized. Lastly, nanocarbon segments obtained from organic synthesis for SWCNT growth are discussed.