Evaluation of the Photocatalytic Activity and Anticorrosion Performance of Electrospun Fibers Doped with Metallic Oxides

This paper reports the development and characterization of a multifunctional coating that combines anticorrosion and photocatalytic properties, deposited by means of the electrospinning technique. In the first step, a functional electrospun fiber mat composed of poly(acrylic acid) (PAA) and beta-cyclodextrin (beta-CD) was obtained, showing high water insolubility and great adhesion increased by means of a thermal crosslinking process (denoted as PAA + beta-CD). In the second step, the fibers were doped with particles of titanium dioxide (denoted as PAA + beta-CD/TiO2) and titanium dioxide plus iron oxide (denoted as PAA + beta-CD/TiO2/Fe2O3). The morphology and fiber diameter of the electrospun mats were evaluated by using confocal microscopy, whereas the presence of the metal oxides in the electrospun fibers was corroborated by scanning electron microscopy (SEM) and X-ray fluorescence (XRF), respectively. In addition, electrochemical tests in saline solution revealed that the sample composed of PAA + beta-CD/TiO2/Fe2O3 showed the highest corrosion protection efficiency of all the samples, which was directly associated to lower corrosion current density and higher corrosion potential. Furthermore, the paper reports a novel approach to in situ determination of methylene blue (MB) degradation onto the coating. The results revealed complete degradation of MB, which is perfectly appreciated by total discoloration of the film in the irradiated zone (from bluish to a white spot). The main conclusions of this research are the efficiency of the electrospun system PAA + beta-CD/TiO2/Fe2O3 for developing photocatalytic activity and corrosion protection and the utility of the dry MB discoloration tests to evaluate photocatalytic activity.