Hydrogen embrittlement mitigation by surface modification: A review on current advances and future perspectives

Hydrogen is emerging as a sustainable energy source that can reduce fossil fuel reliance and associated environmental impact. However, it poses embrittlement challenges for storage and transport materials that affect the widespread deployment of the hydrogen economy. Surface modification of materials by employing coatings, thermochemical, mechanical treatments, and others modifies surface chemistry, microstructure, stress states, and enhances surface integrity. These surface modification methods form physical or chemical barriers that impede hydrogen permeation and lower hydrogen-induced degradation. Though an unfavorable combination of thermodynamic properties, hydrogen solubility, and hydrogen diffusivity of the modified surfaces promotes hydrogen embrittlement mechanisms. This review focuses on a comprehensive overview of various surface modification techniques applied to base materials to counter their hydrogen embrittlement susceptibility. This work emphasizes the relationship between the surface modification methods and their effects on microstructural and mechanical properties, and their contribution to hydrogen storage and transport solutions. Additionally, limitations, challenges, and research gaps related to these surface modification techniques for materials in hydrogen infrastructure are discussed.