A combination of first-principle and thermodynamics study of high-pressured hydrogen uptake on doped Fe(100) surface

Hydrogen, a zero-emission energy carrier, can be transported through existing pipeline networks under high-pressure conditions to achieve environmental and cost-effective benefits. However, these new transportation conditions elevate the hydrogen embrittlement (HE) risk of pipeline steels, particularly during the transportation of ultra-high-pressure supercritical hydrogen. In this study, comprehensive density functional theory (DFT) calculations were performed to analyze hydrogen uptake behavior on Fe (100) surfaces doped with various representative alloying elements in pipeline steels, including Ni, Ti, W, Mo, Mn, Co, Cr, V, Al, and Cu. Moreover, thermodynamic models were developed to predict the dissociative adsorption of hydrogen molecules on the doped-Fe surfaces at the temperature range of 300–800 K and the pressure range of 0.1 MPa–100 MPa. The results revealed that several alloying elements (e.g., W, Mo, Ti, and Ni) could facilitate hydrogen dissociation, while other elements (e.g., Cu, Cr, V, and Al) hinder hydrogen bond cleavage. The developed models further indicated that the presence of high-pressure supercritical hydrogen, rather than gaseous hydrogen, would favor hydrogen bond rupture and enhance hydrogen uptake. In the case of dissociated hydrogen atoms, most of the alloying elements (such as Cu, Al, and Cr) that could prevent hydrogen dissociation were found to have low trap ability on atomic hydrogen. Consequently, a trade-off effect exists between preventing hydrogen molecular dissociative adsorption and irreversibly trapping atomic hydrogen for most of the alloying elements.