Predictive Atomistic Model for Hydrogen Adsorption on Metal Surfaces: Comparison with Low-Energy Ion Beam Analysis on Tungsten

Abstract

We present an analytical thermodynamic model of a surface in contact with a gas phase which enables us to determine the surface coverage of the adsorbate depending on the temperature, pressure and chemical potential of the gas. This model is applied to both the W(110) and W(100) surface of tungsten in contact with hydrogen. The thermodynamic model is built upon data computed by density functional theory that provide the complete electronic and vibrational energetics of both surfaces. It is further compared to experimental measurements of hydrogen coverage during isobar exposure at various temperature acquired via low energy ion scattering and direct recoil spectroscopy techniques. On W(110), the agreement is quantitative provided that an additional degree of freedom is added to the model. This degree of freedom accounts for the translational motion of the adsorbate along 1D channel on the surface. On W(100), surface reconstruction makes the energetics of the system more complex; the full details of the experimental isobar are not well reproduced, although the overall consistency is obtained. We end-up with a thermodynamic model based on DFT data having accurate predictive capabilities to determine the hydrogen coverage of tungsten at any p and T.

Reaction of H2 with polyoxometalate supported Rhodium(0) and Iridium(0) nanoparticles in aqueous suspensions: a kinetic study

“…The reduction of bare POM with H 2 is small in comparison with the reduction of Rh 0 -PW 12 0 40 3− and Ir 0 -PW 12 0 40 3− . Even though the extent of reduction of bare POM by H 2 is small, the absorbance at 750 nm shows that there is a formation of some PW 12 O 40 4–45 (Fig. 5A).…”

“…The metalhydrogen interactions are crucial, especially in the advancement of fuel cells and hydrogen technologies. 5 Numerous studies have been conducted on the interaction of H 2 on transition metal surfaces, especially on the interaction of hydrogen with palladium, [6][7][8][9][10] platinum, [11][12][13] iron, 14,15 ruthenium, [16][17][18][19] tungsten [20][21][22] and nickel [23][24][25] as well as other transition metals. 26 The mechanisms of these processes involve the adsorption of hydrogen on the metal catalyst followed by dissociation and often by migration of H atoms to the support and reactions at remote surface sites.…”

“…The metal-hydrogen interactions are crucial, especially in the advancement of fuel cells and hydrogen technologies. 5 Numerous studies have been conducted on the interaction of H 2 on transition metal surfaces, especially on the interaction of hydrogen with palladium, 6–10 platinum, 11–13 iron, 14,15 ruthenium, 16–19 tungsten 20–22 and nickel 23–25 as well as other transition metals. 26…”

Deuterium uptake, desorption and sputtering from W(110) surface covered with oxygen

“…According to a thermodynamic model parametrized by DFT and phonon calculations, and validated experimentally [38], the maximum coverage for the exposure reported in table 4 is 1 H/W which represents 1.416 × 10 19 Hm −2 . However, after the exposure to D 2 , the sample is stored for 1 h at 300 K under vacuum and D 2 can desorb from the surface before the TDS.…”

“…In this work, we are investigating D desorption from W(110) with pre-adsorbed O atoms at 3 different coverages θ O : clean (θ O = 0), 0.50 ML of O (θ O = 0.5) and 0.75 ML of O (θ O = 0.75). According to DFT calculations and thermodynamics models [18,37,38], the saturation occurs for 1 H/W on the W(110) surface. Thus, n surf (clean) = 1.416 × 10 19 m −2 considering a lattice constant for tungsten of 3.16 Å.…”