Skip to main content
. 2022 Oct 27;12(21):13781–13791. doi: 10.1021/acscatal.2c03609

Figure 2.

Figure 2

On the left, the Ni 2p3/2 and O 1s XPS spectra show, over time (t0 = 0 min, t1 = +15 min, and t2 = +75 min), the in situ reduction of Ni oxide/hydroxide via electrochemically permeating atomic hydrogen at room temperature under vacuum. Fit model using Ni0 (blue), metal oxide (gray), metal hydroxide (orange), and adsorbed water (yellow). On the right, the ratio of the Ni 2p3/2 XPS peak areas of oxidized and metallic species, at t0 = 0 min, as a function of photoelectron kinetic energy (between 200 and 600 eV). Measured values (symbols) and calculated fit (dotted line). From this, the initial thickness of the oxidized surface layer is estimated to be 0.75 ± 0.02 nm.