Mechanism and Evaluation of Hydrogen Permeation Barriers: A Critical Review

Stainless steel is a common material for high-pressured hydrogen storage. However, the extreme pressure reached in these storage systems accelerates the embrittlement of stainless steel caused by hydrogen, thus reducing its lifetime and seriously limiting the development of the hydrogen industry. Adding hydrogen permeation barrier coatings to the surface of stainless steel is one of the most effective approaches to delay or prevent the permeation of hydrogen and its isotopes through the substrate. Despite the relevance of the issue, studies on hydrogen permeation barrier coating materials have not so far been as popular as those on hydrogen storage materials. In this review, the mechanism of hydrogen permeation and the working principle of hydrogen barriers were investigated. On the basis of this, the hydrogen barring coatings were classified, the influence factors and defects of the coatings were analyzed, and the preparation technologies along with the methods of evaluation were summarized. Polymer composites strengthened by graphene and other materials were considered more competitive due to their cost effectiveness, better compactivity, and potential for mass production. This review may supply guidance to the further development of hydrogen permeation barring coating materials.