Hydrogen and Isotope Diffusion in Alloyed or Non-alloyed Palladium Membrane or in Cathodes—Hydrogen Obtained from Solid Polymer Electrolyte

Dear Colleagues,

Improving the production of hydrogen or isotopes is a challenging objective. The challenge addressed in this Special Issue is to provide a comprehensive review illustrating the diverse mechanisms implied by high mobility of hydrogen in palladium lattice and the alloys and mechanisms implied in solid polymer electrolyte for hydrogen production. This review, on these two subjects, will provide a critical reference tool for anyone working on recycling in nuclear fusion power technology and non-polluting powerful energy technology, sensors, and fuel cells using hydrogen. This Special Issue is based on the results of intensive worldwide research efforts and provides the connection between the theoretical aspects of the mechanisms and future practical applications in industry. Consequently, this issue covers three themes concerning these two major subjects:

- Classical gas–gas diffusion in palladium alloy permeators for the purification of hydrogen and isotopes to produce very pure gas. High mobility is based on the pressure-hydrogen concentration isotherms in palladium, and in reality the mechanisms appear more complex than can be imagined. This is why this theme is developed in this issue,

- Diffusion palladium cathode contrasting with gas–gas diffusion. The kinetic and mechanical problems of diffusion in the cathode are entirely different to those in gas–gas diffusion in the permeator in all aspects,

- Solid polymer electrolyte membrane (SPE or PEM), which requires a detailed understanding of the mechanism and technology.

There are also corrosion problems such as stress corrosion cracking by hydride phases in the palladium alloys. There are also problems related to the durability and degradation of polymer electrolyte. Recently, palladium alloys containing rare earth metals have shown considerable promise.

With regard to this Special Issue, I would like to take this opportunity to express my gratitude to all the authors and contributors for their great collaboration, as well as to the readers for their confidence in this issue. I would also like to acknowledge Grace Du, Managing Editor, for her great support during the preparation of this Special Issue. Thanks to all the reviewers for the time they dedicated to reviewing the manuscripts. The authors, from leading academic and industrial research institutes around the world, are highly recognized scientists in these disciplines. Their remarkable work has led to the creation of this Special Issue, which forms the basis of these processes for the industrial preparation of hydrogen and isotopes. In dealing with the fundamental and practical aspects, I hope this edition will provide a detailed view of the mechanisms governing these different processes, providing better understanding for readers in view of industrialization

Dr. Gilbert Bellanger
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• palladium and alloys
• hydrogen and isotope diffusion
• palladium membrane permeator
• palladium membrane cathode
• solid polymer electrolyte
• proton exchange polymer membrane electrolyzer
• hydrogen fuel cell