In Situ Studies of Hydrogen Evolution Kinetics on Pure Titanium Surface: The Effects of Pre-Reduction and Dissolved Oxygen

Abstract

The apparent cathodic current on the Ti surface in acidic solution is composed of three reactions: the reductions of the oxide film, H+, and O2. However, classical electrochemical tests usually provide coupled multi-reaction currents. Furthermore, dissolved oxygen makes in situ measurements significant due to the thermodynamic instability of Ti. In this study, the effects of pre-reduction and dissolved oxygen on hydrogen evolution reaction (HER) kinetics on the Ti surface were investigated by electrochemical and composition characterizations. The HER current was quantitatively separated from the apparent cathodic current from Ti, including the reductions of the oxide film, H+, and O2 by scanning electrochemical microscopy. The HER transfer coefficient and standard rate constant for Ti spontaneously passivated in air (P-Ti) are both 0.48/4.9 × 10–12 cm/s in aerated and O2-saturated solutions, while those for Ti activated by electro-reduction (EA-Ti) are 0.25/3.6 × 10–7 cm/s and 0.25/3.1 × 10–7 cm/s, respectively. The variable HER behavior is caused by the changes in the film electronic structure and composition except for the competition reduction between O2 and H+ as indicated by Mott–Schottky and surface-enhanced Raman spectroscopy. The deviation from 0.5 in the transfer coefficient implies that the Tafel slope and HER mechanism should be analyzed with caution.

Molecular Insights into the Stability of Titanium in Electrolytes Containing Chlorine and Fluorine Ions

“…In this work, a confocal Raman spectrometer (inVia Qontor, Renishaw of UK) was used to investigate the titanium/aqueous solution interface at room temperature and 1 atm. The laser was focused through a 50 × L microscope objective with a 532 nm green laser at the working power of 5 mW. ,, The exposure time for each measurement is 10 s and accumulated once . The high-purity titanium rod (99.99%) with a radius of 1.0 mm used for the experiment was purchased from the China BAOTI Group Co., Ltd.…”

“…The following pretreatment steps are taken before the experiment. The titanium rod was thoroughly polished with 1 μm diamond polishing spray, then cleaned with ethanol, and finally exposed to air for 12 h to develop a spontaneous oxide film. , It is necessary to deconvolute Raman signals between 2800 and 3800 cm –1 to obtain various types of HB components. The detailed measurement steps and spectral decomposition method have been reported in our previous literature. ,, The self-developed Raman cell can ensure a closed solution environment and a fixed liquid film thickness of 50 μm .…”

“…The surface titanium atoms are more likely to react with sufficient oxidants, resulting in a higher valence state and oxygen–titanium ratio. After high-temperature treatment, the amorphous type of Ti x O y or anatase type of passive film transforms into rutile . The rutile configuration is a more stable and chemically resistant titanium dioxide structure. − Therefore, elucidating the interface interaction behavior between the electrolyte components and different types of titanium passive films is crucial for understanding the marine service of titanium and its alloys.…”

Effect of low dissolved oxygen concentration on the defects and composition of regenerated passive film of Ti-6Al-4V alloy under continuous wear

“…Lower dissolved oxygen concentrations (DOCs) in tissue liquid inhibit the generation of passive film, which results in weaker protectivity. 8–10…”

“…Lower dissolved oxygen concentrations (DOCs) in tissue liquid inhibit the generation of passive lm, which results in weaker protectivity. [8][9][10] In the tribocorrosion process, the passive lm of the joint undergoes a break/repair process. 11 The repair speed of the passive lm is determined by the corrosion rate of tribocorrosion.…”