Photoelectrodes with titanate nanotubes sensitized by mesoporphyrin derivative from cashew nut shell

Abstract

Titanate nanotubes (TiNTs) with the chemical composition Na2Ti3O7.nH2O (NaTiNT) were obtained through a hydrothermal method in highly alkaline medium. Protonated titanates nanotubes (H-TiNTs), with the composition H2Ti3O7.nH2O, were prepared by ion exchange reaction through a suspension of Na2Ti3O7nH2O nanotubes in HCl medium, promoting the exchange of Na+ ions by H+. Both Na2Ti3O7.nH2O and H2Ti3O7.nH2O products, as well the TiO2 used as raw material for the nanotubes processing, were used as starting material for the solar cells photoelectrodes sensitized using mesoporphyrin extracted from a precursor of cashew nut shell. Exposing the NaTiNT sample to solar radiation of 1258 W/m2, a short-circuit current density (ISC) of 13 A/cm2 and an open-circuit voltage (VOC) of 370 mV were registered and, a current density of 7.6 A/cm2 and a voltage of 256 mV for the prototype cell based on H-TiNTs. A current density of 1.1 A/cm2 and an open-circuit voltage of 1.6 mV were obtained for the cell using TiO2 as electrode.