The outstanding flexible field emission properties of carbon hybrid films made of vertically aligned N-doped carbon nanotubes grown on mechanically compliant reduced graphene films are demonstrated. The bottom-reduced graphene film substrate enables the conformal coating of the hybrid film on flexible device geometry and ensures robust mechanical and electrical contact even in a highly deformed state. The field emission properties are precisely examined in terms of the control of the bending radius, the N-doping level, and the length or wall-number of the carbon nanotubes and analyzed with electric field simulations. This high-performance flexible carbon field emitter is potentially useful for diverse, flexible field emission devices.

In this study, vertical N-doped carbon nanotube (VNCNT) arrays were decorated with Au, Ru, or Mn nanoparticles, and the effects of the particles on the field-emission properties were investigated. Uniform catalyst nanoparticles were prepared by block copolymer lithography on a graphene film, and the VNCNT arrays were grown from the nanopatterned catalyst particles by plasma-enhanced chemical vapor deposition (PECVD). The surfaces of the VNCNT arrays were subsequently decorated with metal particles, and the vertical alignment of the NCNT arrays was maintained by high-vacuum annealing. The field-emission properties of the metal-particle-decorated VNCNT arrays varied according to the changes in the work-function values, with the Mn-VNCNT field emitter showing the best performance among the emitters tested. Our results revealed that the field-emission properties of VNCNT arrays may be tuned by decoration with metal particles and that particle decoration with a low-work-function material may be used to develop efficient field emitters.

Biomimetic mineralization of vertical N-doped carbon nanotubes is demonstrated as a straightforward route for carbon-based mineral nanocomposites. The N-doped sites along the carbon nanotube backbone play the role of nucleation sites for mineralization.

Metal oxide nanoparticles supported on heteroatom-doped graphitic surfaces have been pursued for several decades for a wide spectrum of applications. Despite extensive research on functional metal oxide nanoparticle/doped carbon nanomaterial hybrids, the role of the heteroatom dopant in the hybridization process of doped carbon nanomaterials has been overlooked. Here, the direct growth of MnOx and RuOx nanoparticles in nitrogen (N)-doped sites of carbon nanotubes (NCNTs) is presented. The quaternary nitrogen (NQ) sites of CNTs actively participate in the nucleation and growth of the metal nanoparticles. The evenly distributed NQ nucleation sites mediate the generation of uniformly dispersed <10 nm diameter MnOx and RuOx nanoparticles, directly decorated on NCNT surfaces. The electrochemical performance of the resultant hybridized materials was evaluated using cyclic voltammetry. This novel hybridization method using the dopant-mediated nucleation and growth of metal oxides suggests ways that heteroatom dopants can be utilized to optimize the structure, interface and corresponding properties of graphitic carbon-based hybrid materials.