Hydrogen loading and reduction of iron oxides on steel studied by XPS with an in situ cell

• Custom-made in situ cell for hydrogen charging in XPS is presented. • Iron oxide reduction was observed in the high-resolution Fe2p spectrum. • Thickness of oxide layers was calculated with the modified Strohmeier equation. • Identification of the reaction mechanism of iron oxide reduction. A self-developed liquid in situ cell gives insights into the diffusion of hydrogen in steel and its interaction with iron oxides. The cell initiates a corrosive reaction on one side of a galvanized steel sample within an X-ray photoelectron spectroscopy (XPS) system while changes of iron oxides on the opposite side attributed to diffused hydrogen are recorded. The reduction leads to a continuous alteration in the high-resolution Fe2p peak which is iteratively measured during hydrogen permeation. A detailed analysis of the process, involving layer thickness evaluation with the modified Strohmeier equation leads to a model of the developed oxide structure.