In‐Situ Growth of Ultrathin Films of NiFe‐LDHs: Towards a Hierarchical Synthesis of Bamboo‐Like Carbon Nanotubes

The synthesis of ultrathin films (UTFs) of NiFe‐LDHs has been achieved by means of an in situ hydrothermal approach, leading to a flat disposition of the LDH crystallites on the substrate, in clear contrast to the most common perpendicular orientation reported to date. Experimental factors like time of synthesis or the nature of the substrate, seem to play a crucial role during the growing process. The 2D morphology of the NiFe‐LDH crystallites was kept after a calcination procedure, leading to a topotactic transformation into mixed‐metal oxide platelets. Hereby, in order to study the catalytic behavior of our samples, a chemical vapor deposition process is explored upon the as‐synthesized films. In presence of a carbon source (ethylene), these films catalyze a preferential low‐temperature (550 °C) growth of bamboo‐like carbon nanotubes, in stark contrast to the different mixture of carbon nanoforms obtained from the bulk samples. This work opens the door for the development of UTFs based on LDHs, which may be of utmost importance in a wide range of potential applications ranging from magnetic storage, catalysis or biomedical applications, to electrochemical batteries, anti‐corrosion and superhydrophobic coatings.