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. 2022 Sep 19;12(19):11974–11983. doi: 10.1021/acscatal.2c03692

Figure 3.

Figure 3

Reaction front identification using correlative microscopy: (a) bright-field LEEM images of oxygen front propagation (frames 1 and 2) and hydrogen front propagation (frames 3 and 4) on the Rh(7 5 4) domain at pH2 = 4.5 × 10–7 mbar, pO2 = 5.0 × 10–7 mbar, T = 468 K, and electron energy = 2.5 eV; (b) the same, but imaged with XPEEM, the used binding energy window is shaded gray in panels (d) and (e). In the dashed rectangular regions, the image contrast is enhanced locally for better front visibility, the insets in frames 3 and 4 illustrate the front positions; (c) local LEEM (left) and XPEEM (right) image intensity profiles obtained from the original data along the A–A′ line in panels (a) and (b), the principle of the determination of the front propagation velocity is illustrated; (d) Rh 3d XPS spectra locally measured on the Rh(7 5 4) domain for the catalytically inactive state in H2 oxidation. Deconvolution of the peaks provides the Rhb and RhO2/3 components; (e) the same, but for the catalytically active state, with an additional RhO1/4 component present in the deconvolution, identifying the hydrogen front.