Ba0.5Gd0.8La0.7Co2O6−δ Infiltrated BaZr0.8Y0.2O3-δ Composite Oxygen Electrodes for Protonic Ceramic Cells

In this study, a composite oxygen electrode is prepared by infiltrating a protonic-electronic conducting material, Ba0.5Gd0.8La0.7Co2O6−δ (BGLC) into a proton-conducting BaZr0.8Y0.2O3-δ (BZY20) backbone. The composite oxygen electrode is studied in a symmetrical cell configuration (BGLC-BZY20//BZY20//BGLC-BZY20). The electrode and cell performance are characterized via electrochemical impedance spectroscopy (EIS) with varying the operating conditions, including temperatures, oxygen, and steam partial pressures, with the purpose to identify and characterize the different electrochemical processes taking place in the oxygen electrode. Three electrode reaction processes are observed in the impedance spectra, which are tentatively assigned to i) diffusion of adsorbed oxygen/proton migration/hydroxyl formation, ii) oxygen reduction, and iii) charge transfer, going from the low- to high-frequency range. The BGLC-BZY20 electrode developed in this work shows a low polarization resistance of 0.22, 0.58, and 1.43 Ω cm2 per single electrode in 3 % humidified synthetic air (21% O2/79% N2) at 600, 550, and 500 °C, respectively. During long-term measurement, the cell shows no degradation in the first 350 hours but degrades afterward possibly due to insufficient material stability.

A Review of Electrochemical Cells with Geometrically Well-defined Interfaces for Solid Oxide Fuel Cell Anodes

A solid oxide fuel cell (SOFC) is a high-temperature (above 750℃) energy conversion device that generates electricity with high efficiency and low CO2 emission. It is essential to develop high-activity electrodes for its commercialization by lowering the operating temperature to below 700℃. Understanding the electrode reaction kinetics can provide fundamental insights for the rational design of high-performance electrodes. However, the three-dimensional porous microstructures of the SOFC electrodes make it difficult to analyze the reaction processes precisely. To overcome this issue associated with the conventional electrodes, the model electrodes with geometrically well-defined interfaces have been widely employed. In this paper, focusing on the SOFC anodes, the fabrication techniques, cell types, analysis tools, and the modeling studies in the literature will be reviewed.

Bipolar Membrane and Water Splitting in Electrodialysis

The traditional view of the conductivity of electrolytes is based on the mobility of ions in an electric field. A new concept of water conductivity introduces an electron–hole mechanism known from semiconductor theory. The electrolyte ions in the hydrogen bond network of water imitate the structure of a doped silicon lattice. The source of the current carriers is the electrode reaction generating H+ and OH− ions. The continuity of current flow is provided through the electron–hole mechanism, and the movement of electrolyte ions is only a side process. Bipolar membrane in the semiconductor approach is an electrochemical diode forward biased. Generation of large amounts of H+ and OH− has to be considered as a result of current flow and does not require any increase in the water dissociation rate. Bipolar membranes are essential in electrodialysis stacks for the recovery of acids and bases by salt splitting. Graphic Abstract

Influence of Diffusion through a Porous Film under Electrode Surface in Chronoamperometry Problems

In the presented work on chronoamperometry, the Cottrell model has been generalized by taking into account a thin porosity layer covering the surface of the electrode and Tafel kinetics of an electrode reaction. The effective diffusion coefficient inside a porosity layer is calculated by Bruggeman’s law. It is shown that in the quasi-stationary approximation of diffusion inside a thin porous layer, the chronoamperometry problem can be solved analytically. The obtained solution has been compared with the results of direct numerical simulations and a good agreement is shown. Limiting cases of the solution related to low and high porosity are considered.

Production of green hydrogen by efficient and economic electrolysis of water with super-alloy nanowire type electrocatalysts

Green hydrogen production from the electrolysis of water has good application prospect due to its renewability. The applied voltage of 1.6-2.2V isrequired in the traditional actual water electrolysis process although the the oretical decomposition potential of electrolyzing water is 1.23V. The high overpotential in the electrode reaction results in the high energy-consuming for the water electrolysis processes. The overpotentials of the traditional Ru, Ir and Pt based electrocatalysts are respectively 0.3V, 0.4V and 0.5V, furthermore use of the Pt, Ir and Ru precious metal catalysts also result in high cost of the water electrolysis process. For minimizing the overpoten tials in water electrolysis, a novel super-alloy nanowire electrocatalysts have been discovered and developed for water splitting in the present pa per. It is of significance that the overpotential for the water electrolysis on the super-alloy nanowire electrocatalyst is almost zero. The actual voltage required in the electrolysis process is reduced to 1.3V by using the novel electrocatalyst system with zero overpotential. The utilization of the super-alloy nanowire type electrocatalyst instead of the traditional Pt, Ir and Ru precious metal catalysts is the solution to reduce energy consumption and capital cost in water electrolysis to generate hydrogen and oxygen.

Electrical conductivity of Self-assembling Peptide-semiconducting dye Conjugate nanofibre networks

Conjugates comprising a semiconducting dye (Thiophene-diketopyrrolopyrrole, TDPP-dye) attached to a self-assembling peptide (HEFISTAH) assemble into long nanofibers. Well-ordered Langmuir-Blodgett films of these materials can be prepared. Networks of these nanofibres can be deposited to bridge electrodes. Although similar systems have been proposed as organic semiconductors, in this case, no electronic conductivity was observed. Instead, the fibres behaved as ionic (probably proton) conductors as a consequence of adsorbed water. A strong dependence of electrical conductivity on relative humidity and fibre network density was demonstrated. The system of nanofibers bridging gold electrodes behaved as an electrolytic cell, with oxygen reduction as a limiting electrode reaction.

The corrosion behavior and cracking susceptibility of the disbonded coating in the X80 steel pipeline by theoretical simulations and experimental measurements

The corrosion behavior and cracking susceptibility of the disbonded coating in the X80 steel pipeline were investigated by different methods. The oxygen content in the trapped solution decreased rapidly with the formation of an airtight disbonded area. The airtight system affected the electrode reaction process, resulting in the inhibition of corrosion in the center of the disbonded area and the more refined surface finish of the sample. The bottom of the disbonded area underwent a relatively intense and accelerated corrosion reaction controlled by the diffusion process. The cracking susceptibility of the X80 steel firstly decreased and then increased in the pointing direction.

Poisoning Effect of CO: How It Changes Hydrogen Electrode Reaction and How to Analyze It Using Differential Polarization Curve

The hydrogen electrode reaction (HER) on Pt electrode in a H2SO4 solution when CO gas was injected/stopped was studied using polarization resistance curve [...]