HonPt(110): An atypical chemisorption site at low coverages

Chemisorption of hydrogen on the missing-row Pt(110)-(1 × 2) surface

“…This fact may resolve the controversy about the a-state: Whereas in some of the earlier experiments [12,13] the high exposures needed for occupation of the a-state have not been applied, a higher sticking coefficient at higher coverages (see figures 6 and 2 in Refs. [2,20], respectively) allowed the detection of the a-state at exposures below 60 L. For a general overview, we first repeat the main findings for the b 2 state (low coverage) as already published (figure 4, see [9]). Then we give more and yet unpublished details on the DFT geometries and energetics at low coverage (see table1) and discuss the experiments and calculation for the b 1 and a-states at higher coverage.…”

“…Recently, we reported an atypical bonding geometry of the so-called b 2 -state at a coverage of 0.5 hydrogen atoms per 1 · 1 unit cell (0.5 ML) [9]: Contrary to the general expectation [10,11] and to proposals specific to the Pt(110) surface [12][13][14][15], hydrogen adsorbs in the low coordinated short bridge site on top of the outermost platinum rows. The current paper includes both, the former low coverage results and additionally experimental and theoretical investigations for higher coverages up to saturation.…”

“…Table 1, not published in Ref. [9], shows the calculated interlayer spacings and Generally, the table shows that the positions with highest binding energies are located in the vicinity of the rim and correlate with the biggest interlayer spacings d 12 . Adsorption in the trough is most unfavoured and leads to the lowest d 12 .…”

“…For details, the reader is referred to Ref. [9]. According to the I/V-LEED analysis, the most important change upon hydrogen adsorption is the derelaxation in the first interlayer spacing d 12 (see figure 4): The interlayer spacing in (110) direction in the bulk, for the clean and for the b 2 -H/Pt(110) is d 12 (bulk) = 1.38 Å , d 12 (clean) = 1.15 Å , and d 12 (b 2 ) H) = 1.25 Å , respectively.…”

Analysis of temperature effects on hydrogen and OH adsorption on Pt(1 1 1), Pt(1 0 0) and Pt(1 1 0) by means of Gibbs thermodynamics

“…(43) has been obtained by combination of Eqs. (26) and (28). Then, the adsorption pseudocapacity can be obtained from:…”