In this review the phenomenon of proton conductivity in materials and the elements of proton conduction mechanismsproton transfer, structural reorganization and diffusional motion of extended moietiesare discussed with special emphasis on proton chemistry. This is characterized by a strong proton localization within the valence electron density of electronegative species (e.g., oxygen, nitrogen) and self-localization effects due to solvent interactions which allows for significant proton diffusivities only when assisted by the dynamics of the proton environment in Grotthuss and vehicle type mechanisms. In systems with high proton density, proton/proton interactions lead to proton ordering below first-order phase transition rather than to coherent proton transfers along extended hydrogen-bond chains as is frequently suggested in textbooks of physical chemistry. There is no indication for significant proton tunneling in fast proton conduction phenomena for which almost barrierless proton transfer is suggest...

Proton Conductivity: Materials and Applications

The oxidation behaviour of metals and alloys at high temperatures in atmospheres containing water vapour: A review

High temperature electrolysis in alkaline cells, solid proton conducting cells, and solid oxide cells.

A survey is made of high-temperature membranes and several possible applications of membrane reactors for integration in power generation cycles with CO2 capture. Current performance and limitations of relevant inorganic membranes are presented and discussed. Integrated H2, O2 or CO2 membrane separation is analysed and it is concluded that development of power plant concepts including membrane technology is not yet fully explored. Significant design optimisation would be required in order to identify efficient, feasible and environmentally sound technical solutions. In addition, further development and validation of performance of membranes in real applications are needed.

High-temperature membranes in power generation with CO2 capture

Review of Electrochemical Hydrogen Sensors

Much attention is paid some perovskite oxides because they can be used as proton-conductive solid electrolytes in many attractive applications, for example, in fuel cells, hydrogen pumps, steam electrolyzers, hydrogen analyzers, hydrogen or steam sensors, electrochemical reactors, and as devices for fundamental studies of some hydrogen-metal systems. The conductivities of a protonic conductor, 1.0 mole percent (m/o) In{sub 2}O{sub 3}-doped CaZrO{sub 3}, were measured in an atmosphere containing hydrogen or deuterium with the 4-wires ac impedance technique at temperatures ranging from 623 to 673 K. In high oxygen activities, H{sup +}/D{sup +}-isotope effects were observed below about 1100 K. The ratio of conductivities of protons to deuterons increased as the temperature decreased and rose to about 1.6 at 673 K. It was made clear by this observation that at low temperatures electrical conduction is dominated by proton and at high temperatures by positive hole, respectively. On the other hand, at high hydrogen activities, the isotopes effects were observed up to about 1600 K and it was concluded that proton is dominant below this temperature. Over that temperature, the isotope effects vanished and the electrical conductivities were independent of gas potentials. It was concluded that electrical conduction over 1600 K andmore » was dominated by oxide ions. As electrical carriers obey the thermally activated process, the activation energies were calculated by the least squares method. The obtained activation energies of protons, deuterons, positive holes, and oxide ion vacancies were 0.74 {+-} 0.05, 0.70 {+-} 0.05, 1.21 {+-} 0.07, and 2.5 {+-} 0.5 eV, respectively. Based on the model of defects equilibria and these experimental findings, the protonic conduction domain of the specimen was determined and is represented in temperature-potential diagrams.« less

Teruo Ohashi

Papers

Protonic Conduction Domain of Indium‐Doped Calcium Zirconate

A new hydrogen sensor for molten aluminum

Hydrogen sensor for molten metals usable up to 1500 K

Proton conductors of oxide and their application to research into metal-hydrogen systems

Measurements of hydrogen permeation through fused silica and borosilicate glass by electrochemical pumping using oxide protonic conductor