Template synthesis for the creation of photo- and electrocatalysts

Abstract

This work reports the optimal conditions for the synthesis of a matrix for the creation of photo- and electrocatalysts. Specifically, it is shown that TiO2 nanotube arrays has a high specific surface area and improved catalytic properties, but has low conductivity and weak structural strength, that requires further optimization. The original TiO2 nanotubes were prepared by anodizing of Ti foil in ethylene glycol with 0.3 wt.% ammonium fluoride and 2 vol.% water at a constant potential, followed by another anodizing in ethylene glycol with 5 wt.%H3PO4. The reduction was conducted in 1 M HClO4. Some samples were thermally treated in the air using tube furnace. The study demonstrates how the synthesis conditions of the coating affect the morphology and stoichiometry of the resulting oxide coating. For the obtained materials, the Tafel slope in the oxygen evolution reaction is determined by the semiconductor characteristics of the coating, which, in turn, depend on the stoichiometry of the synthesized oxide. The higher the stoichiometry in the oxygen sublattice, the fewer the charge carriers and the greater the contribution of the semiconductor component to the Tafel slope. As for hydrogen evolution, the layers obtained after heat treatment show a lower Tafel slope (175 mV dec–1).