Hydrogen barrier coatings: Application and assessment

Hydrogen embrittlement (HE) threatens the structural integrity of industrial components exposed to hydrogen-rich environments. This review critically explores hydrogen barrier coatings (HBCs), polymeric, metallic, ceramic, and composite, their application and assessment, focusing on measured effectiveness in limiting hydrogen permeation and hydrogen embrittlement. Also, coating application methods and permeation assessment techniques are evaluated. Recent advances in nanostructured and hybrid coatings are emphasized, highlighting the pressing need for durable, scalable, and environmentally sustainable hydrogen barrier coatings to ensure the reliability of emerging hydrogen-based energy solutions. This comprehensive critical review further distinguishes itself by linking coating deposition methods to defect-driven transport behaviour, critically assessing permeation test approaches. It also highlights the emerging role of polymeric and hybrid multilayer coatings with direct implications for advanced and reliable hydrogen production, storage, and transport infrastructure.