Tel.

The passive and transpassive behaviour of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine solution (400 g/l) at 25º C using potentiostatic polarisation combined with electrochemical impedance spectroscopy and Mott-Schottky analysis. The passive film formed on Alloy 31 has been found to be p-type and/or n-type in electronic character, depending on the film formation potential. The thickness of the film formed at potentials within the passive region increases linearly with applied potential. The film formed at transpassive potentials is thinner and more conductive than the film formed within the passive region. These observations are consistent with the predictions of the Point Defect Model for passive and transpassive films on metals and alloys.

ElsevierFernández Domene, RM.; Sánchez Tovar, R.; Lucas-Granados, B.; Roselló-Márquez, G.; Garcia-Anton, J. (2017). A simple method to fabricate high-performance nanostructured WO3 photocatalysts with adjusted morphology in the presence of complexing agents. (J. .The rich and complex chemistry of tungsten was employed to synthesize innovative WO3 nanoplatelets/nanosheets by simple anodization in acidic electrolytes containing different concentrations of complexing agents or ligands, namely Fand H2O2. The morphological and photoelectrochemical properties of these nanostructures were characterized. The best of these nanostructures generated stable photocurrent densities of ca. 1.8 mA cm -2 at relatively low bias potentials (for WO3) of 0.7 VAg/AgCl under simulated solar irradiation, which can be attributed to a very high active surface area.This work demonstrates that the morphology and dimensions of these nanostructures, as well as their photoelectrochemical behavior, can be controlled by adjusting the ligand concentration in the electrolytes, hence providing an easy and non-expensive route to fabricate and customize high-performance nanostructured photocatalysts for clean energy production and environmental applications.

This work studies the photoelectrochemical behavior of novel ZnO/ZnS heterostructures obtained by means of anodization in water and glycerol/water/NH 4 F electrolytes with different Na 2 S additions under controlled hydrodynamic conditions. For this purpose different techniques such as Field Emission Scanning Electronic Microscopy (FE-SEM) with EDX, Raman spectroscopy and photoelectrochemical water splitting tests under standard AM 1.5 conditions have been carried out. The obtained results showed that the hydrodynamic conditions promoted an ordered nanotubular morphology which facilitates electron-hole separation and consequently, the photoelectrochemical activity for water splitting is enhanced. Additionally, the effect of glycerol in the anodization solutions seems to be beneficial for increasing the dark current photostability.

The influence of alloying elements on the electrochemical and semiconducting properties of thin passive films formed on several steels (carbon steel, ferritic and austenitic stainless steels) has been studied in a highly concentrated lithium bromide (LiBr) solution at 25º C, by means of potentiodynamic tests and Mott-Schottky analysis.The addition of Cr to carbon steel promoted the formation of a p-type semiconducting region in the passive film. A high Ni content modified the electronic behaviour of highly alloyed austenitic stainless steels. Mo did not modify the electronic structure of the passive films, but reduced the concentration of defects.

In the present work, a new WO 3 nanostructure has been obtained by anodization in a H 2 SO 4 /NaF electrolyte under controlled hydrodynamic conditions using a Rotating Disc Electrode (RDE) configuration. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FE-SEM), Confocal Raman Microscopy and photoelectrochemical measurements. The new nanostructure, which consists of nanoplatelets clusters growing in a tree-like manner, presents a very high surface area exposed to the electrolyte, leading to an outstanding enhancement of its photoelectrochemical activity. Obtained results show that the size of nanostructures and the percentage of electrode surface covered by these nanostructures depend strongly on the rotation velocity and the electrolyte composition.

The cavitation corrosion behaviour of commercially pure Grade 2 titanium in a 992 g/l LiBr solution has been investigated at 25º C using an ultrasound device. Cavitation was found to have more influence on the anodic branch than on the cathodic branch, shifting the corrosion potential, Ecorr, and the OCP value towards more negative potentials, and increasing the corrosion current density, icorr, by six times. The repassivation kinetics of Grade 2 titanium have also been studied in the 992 g/l LiBr solution, at 25º C and various applied potentials, using cavitation to damage the electrode surface. The repassivation kinetics have been analysed in terms of the current density flowing from the area damaged by cavitation, and the results were described by the equation i(t) = A•t-n. At potentials within the passive region, the passive film grew according to the high-field ion conduction model in which log i(t) is linearly proportional to 1/q(t). The damage generated during the potentiostatic tests has been quantified by means of Confocal Laser Scanning Microscopy.

Improvement in photocatalytic activity of stable WO3 nanoplatelet globular clusters arranged in a tree-like fashion: Influence of rotation velocity during anodization. Applied Catalysis B: