Vacuum template synthesis of multifunctional nanotubes with tailored nanostructured walls

A three-step vacuum procedure for the fabrication of vertical TiO2 and ZnO nanotubes with three dimensional walls is presented. The method combines physical vapor deposition of small-molecules, plasma enhanced chemical vapor deposition of inorganic functional thin films and layers and a postannealing process in vacuum in order to remove the organic template. As a result, an ample variety of inorganic nanotubes are made with tunable length, hole dimensions and shapes and tailored wall composition, microstructure, porosity and structure. The fabrication of multishell nanotubes combining different semiconducting oxides and metal nanoparticles is as well explored. This method provides a feasible and reproducible route for the fabrication of high density arrays of vertically alligned nanotubes on processable substrates. The emptying mechanism and microstructure of the nanotubes have been elucidated through SEM, STEM, HAADF-STEM tomography and energy dispersive X-ray spectroscopy. In this article, as a proof of concept, it is presented the straightforward integration of ZnO nanotubes as photoanode in a photovoltaic cell and as a photonic oxygen gas sensorJunta de Andalucia TEP8067 FQM-6900 FQM 1851 P12-FQM-2265España Mineco CONSOLIDER-CSD 2008-00023 MAT2013-40852-R MAT2013-42900-P MAT2013-47192-C3-3-R RECUPERA 2020Unión Europea FP/2007-2013 312483 - ESTEEM2 291522 - 3DIMAGE REGPOT-CT-2011-285895-Al-NANOFUNC