Doped TiO2 as support of iridium electrocatalysts for the oxygen evolution reaction

Abstract

In this work, highly porous supports of TiO2 nanotubes have been synthesized for IrO2 electrocatalysts doped with niobium, tin and cobalt at 3 % atomic composition. Supported and unsupported carriers have been synthesised following a hydrothermal method in alkaline media followed by calcination, employing metal oxides as precursors and two polymorphs of titanium dioxide (rutile or anatase/rutile -Degussa P25- phases). A total of eight samples have been obtained and characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) to corroborate the formation of nanotubes with high surface area determined by nitrogen physisorption. Raman spectroscopy revealed the crystallization of nanotubes in its anatase phase and the introduction of the dopant element in the structure, with partial segregation of cobalt. Electrocatalysts differing in IrO2 catalyst content have also been synthesized from the prepared supports, and three different methods have been employed for the dispersion of the catalyst in the form of nanoparticles on the substrates. Its characterization has been carried out using electrochemical techniques to determine its activity in front of the evolution of O2 in acidic media. The corresponding results show that Nb is an appropriate doping element of the TNTs that may be used as supports to improve the activity of IrO2 as electrocatalyst for the latter reaction