Carbon nanotube@silicon carbide coaxial heterojunction nanotubes as metal-free photocatalysts for enhanced hydrogen evolution

Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes. In this work, one-dimensional coaxial core-shell carbon nanotubes@SiC nanotubes were successfully synthesized via in situ growth of SiC coatings on carbon nanotubes by a vapor-solid reaction between silicon vapor and carbon nanotubes. High-resolution transmission electron microscope images show that SiC and carbon nanotubes link to form a robust heterojunction with intrinsic atomic contact, which results in efficient separation of the photogenerated electron-hole pairs on SiC and electron transfer from SiC to carbon nanotubes. Compared with those of similar materials such as pure SiC nanocrystals and SiC nanotubes, the metal-free carbon nanotubes@SiC exhibits an enhanced photocatalytic activity for hydrogen evolution, which is attributed to the enhanced light absorption and the efficient interfacial charge transfer/separation brought about by their one-dimensional coaxial nanoheterostructures. Moreover, the photocatalytic stability of the metal-free carbon nanotubes@SiC was tested for over 20 h without any obvious decay.