Mesoporous silica coating on carbon nanotubes: Layer-by-layer method

It is of great interest to develop a simple, general, and easy-handling procedure for mesoporous silica coating. A facile, single-step method to coat iron oxide nanoparticles has been reported by Hyeon's group. However, up to present, this method only successfully applied to those zero-dimensional nanostructures heavily capped by cetyltrimethyl ammonium bromide (CTAB); no others are reported. It is unknown how this simple method is feasible in coating those nanostructures not capped by CTAB. Herein, using carbon nanotubes (CNTs) as the model, through an analogous layer-by-layer assembly method, many more CTAB molecules were found to anchor to CNTs, on which uniform mesoporous silica shells can successfully be formed by Hyeon's coating method. We believe that this contribution will pave the way for advancing the single-step method to become a general protocol in the mesoporous silica coating field.