Objective Hydrogen energy has drawn significant attention as the strategy of energy transition pushing forward, making it essential to establish reliable hydrogen transmission systems. For the construction of hydrogen service pipelines, it is vital to evaluate the risk of material failure due to hydrogen embrittlement in pipes. Hydrogen embrittlement occurs when hydrogen comes into contact with pipeline steel through a process consisting of six steps, among which hydrogen generation and adsorption lack of well-developed theories, leading to disparities among scholars in their understanding of the hydrogen adsorption mechanism. Therefore, studying the dissociative adsorption mechanism of hydrogen on pipeline steel is particularly crucial.

Methods Focusing on hydrogen generation and adsorption, this paper presents a systematic review of the dissociative adsorption mechanism of hydrogen on pipeline steel. Lennard-Jones potential curves are incorporated to illustrate the interaction process between hydrogen and the iron surface. The dissociative adsorption modes of hydrogen on the iron surface were simulated and calculated leveraging thermodynamics and density functional theory. By analyzing orbital bonding and charge transfer, the dissociative adsorption mechanism of hydrogen on the iron surface was identified. This paper summarizes three influencing factors in the dissociative adsorption of hydrogen: the environment, the surface, and the hydrogen itself, while proposing corresponding methods to inhibit the dissociative adsorption of hydrogen.

Results Hydrogen was found to be adsorbed on the surface of pipeline steel through activated dissociation into hydrogen atoms, which then enter the pipes. This process follows the primary mechanism in which orbital hybridization between H₂ and Fe leads to the rupture of the H-H bonds and the subsequent formation of H-Fe bonds. Several factors were observed to influence the dissociative adsorption of hydrogen to varying degrees, including hydrogen concentration, hydrogen flow state, gas impurities, temperature, and the condition of the iron surface. Based on these findings, three methods were proposed to enhance hydrogen resistance: coating, corrosion films, and protective gas. All these methods aim to prevent hydrogen from coming into contact with pipeline steel and causing embrittlement from the perspective of surface adsorption, with the protective gas method identified as the most economical and convenient option.

Conclusion This research clarifies the specific process of H₂ dissociative adsorption on the surface of pipeline steel. Future research is recommended to explore the dissociative adsorption of hydrogen under multi-factor coupling conditions, to identify economical and effective hydrogen resistance options. These outcomes will establish a foundation for the integrity management of hydrogen service pipelines and ensure the safety of pipes in contact with hydrogen.