Comparison of electrochemical impedance spectra for electrolyte-supported solid oxide fuel cells (SOFCs) and protonic ceramic fuel cells (PCFCs)

Protonic ceramic fuel cells (PCFCs) are expected to achieve high power generation efficiency at intermediate temperature around 400–600 °C. In the present work, the distribution of relaxation times (DRT) analysis was investigated in order to deconvolute the anode and cathode polarization resistances for PCFCs supported on yttria-doped barium cerate (BCY) electrolyte in comparison with solid oxide fuel cells (SOFCs) supported on scandia-stabilized zirconia (ScSZ) electrolyte. Four DRT peaks were detected from the impedance spectra measured at 700 °C excluding the gas diffusion process for ScSZ and BCY. The DRT peaks at 5 × 102–1 × 104 Hz and 1 × 100–2 × 102 Hz were related to the hydrogen oxidation reaction at the anode and the oxygen reduction reaction at the cathode, respectively, for both cells. The DRT peak at 2 × 101–1 × 103 Hz depended on the hydrogen concentration at the anode for ScSZ, while it was dependent on the oxygen concentration at the cathode for BCY. Compared to ScSZ, steam was produced at the opposite electrode in the case of BCY, which enhanced the cathode polarization resistance for PCFCs.

Inhibition and Adsorption Using Thiazole-2-Carboxylic Acid as an Anti-Corrosive for Copper in HCl Media

This research studied inhibition and adsorption using thiosol-2-carboxylic acid as an anti-corrosive for copper in an acidic environment. The aim of the study was to evaluate the inhibition efficiency of chemical inhibitors through two methods of weight loss, anode and cathode polarization, when concentrations of the inhibitor ranged from 100 to 250 ppm and at temperatures ranging from 40–60°C. The results showed that greater concentration of the inhibitor resulted in less corrosion and increased inhibition efficiency. This indicates the effectiveness of the inhibitor. By forming a layer on the copper surface and through the occurrence of adsorption due to the presence of nitrogen, sulfur and hydroxyl groups, the inhibitor transfers electrons from these groups to the surface of the metal, thus creating a protective layer that protects it from external influences.

Influence of cathodic polarization on the properties of epoxy powder coatings

The article discusses the effect of cathode polarization on the protective properties of powder epoxy coatings, assesses their operational reliability, statistics of failures and describes the problems found during their operation. In the process of applying commercially available pipes with epoxy powder coating on the existing gas pipeline, a not previously manifested defect was observed - the formation of dome-shaped swellings. This led to some restrictions on the use of epoxy powder coatings. With the advent of a new generation of epoxy materials, as well as in connection with the revision of the regulatory documentation GOST R 51164-98, the issue of removing these restrictions on their use for insulating large diameter pipes (up to 1,420 mm). Without additional protection has become topical. As a result, it became necessary to estimate the probability of the appearance of defects of this type when using modern powder coatings. We carried out laboratory studies of the effect of cathode polarization on the properties of modern two-layer epoxy coatings after exposure to them of shock loads of a certain size. The results indicate that the impact of such a mechanical load may cause the appearance of microdefects of the coating, which are not determined by the existing methods of control. Due to the penetration of electrolyte under the coating and the occurrence of certain physicochemical and electrochemical processes that are enhanced by imposing the potential of cathodic protection and increasing the operating temperature, these microdamages can serve as active centers for the formation of a cupola-shaped swelling.

Electrocatalytic Properties of Nickel Foam-Based Ni-Mo, Ni +Mo and Ni+Mo/Ni-Mo Electrodes for Hydrogen Evolution Reaction

Nickel foam-based Ni-Mo alloy electrodes, Ni+Mo composite electrodes and Ni+Mo/Ni-Mo composite alloy electrodes were prepared by eletrodeposition, and the electrocatalytic characteristics for hydrogen evolution reaction (HER) in 30wt% KOH solution were investigated by cathode polarization curve and electrochemical impedance spectroscopy (EIS). The experimental results show that in comparison with nickel foam electrodes, these electrodes exhibit a lower overpotential, a higher exchange current density and a larger real surface area for HER. At 30°C and current density of 200 mA/cm2, the overpotentials of foam Ni electrodes, nickel foam-based Ni-Mo alloy electrodes, Ni+Mo composite electrodes, Ni+Mo/Ni-Mo electrodes are respectively 506, 252, 336, 202 mV. The nickel foam-based Ni+Mo/Ni-Mo composite alloy electrode had the highest HER electrocatalytic activity.