Inhibitive action of Cystine on the corrosion of low alloy steel ASTM A213 grade T22 in sulfamic acid solutions

AbstractThe effect of Cystine on the corrosion behavior of low alloy steel ASTM A213 grade T22 in 0.5M sulfamic acid solutions have been investigated by various electrochemical techniques. The study was performed using electrochemical impedance spectroscopy (EIS) and the recent technique electrochemical frequency modulation (EFM). The results of the investigation show that the inhibition efficiency increased with increasing inhibitor concentration, but decreased with increasing the solution temperature and stirring velocity. All the collected results from the two techniques are in good agreements, which confirm the ability of EFM technique for monitoring the corrosion inhibition under the studied conditions

Aluminum Titania Nanoparticle Composites as Nonprecious Catalysts for Efficient Electrochemical Generation of H₂

In this paper, we demonstrated, for the first time, aluminum titania nanoparticle (Al-TiO₂ NP) composites with variable amounts of TiO₂ NPs as nonprecious active catalysts for the electrochemical generation of H₂. These materials were synthesized by mixing desired amounts of hydrogen titanate nanotubes (TNTs), fabricated here by a cost-effective approach at moderate hydrothermal conditions, with aluminum powder (purity 99.7%; size 35 μm). The mixture was compacted under an applied uniaxial stress of 300 MPa followed by sintering at 500 °C for 1 h. After sintering had been completed, all TNTs were found to convert to TiO₂ NPs (average particle size 15 nm). Finally, Al-<i>x</i>TiO₂ NP nanocomposites (<i>x</i> = 1, 3, 5, and 10) were obtained and characterized by scanning electron microscopy/energy-dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscopy. The hydrogen evolution reaction (HER) activity of these materials was studied in 0.5 M H₂SO₄ at 298 K using polarization and impedance measurements. The nanocomposite of chemical composition Al-5% TiO₂ NPs showed the best catalytic performance for the HER, with an onset potential (<i>E</i>_HER), a Tafel slope (β_c), and an exchange current density (<i>j</i>₀) of −100 mV (RHE), 59.8 mV decade^–1, and 0.14 mA cm^–2, respectively. This HER activity is not far from that of the commercial platinum/carbon catalyst (<i>E</i>_HER = 0.0 mV, β_c = 31 mV dec^–1, and <i>j</i>₀ = 0.78 mA cm^–2). The best catalyst also exhibited good stability after 10000 repetitive cycles with negligible loss in current