Water adsorption and dissociation on BeO(001) and (100) surfaces

Abstract

Plateaus in water adsorption isotherms on hydroxylated BeO surfaces suggest significant differences between the hydroxylated (100) and (001) surface structures and reactivities. Density functional theory structures and energies clarify these differences. Using relaxed surface energies, a Wulff construction yields a prism crystal shape exposing long (100) sides and much smaller (001) faces. This is consistent with the BeO prisms observed when beryllium metal is oxidized. A water oxygen atom binds to a single surface beryllium ion in the preferred adsorption geometry on either surface. The water oxygen/beryllium bonding is stronger on the surface with greater beryllium atom exposure, namely the less-stable (001) surface. Water/beryllium coordination facilitates water dissociation. On the (001) surface, the dissociation products are a hydroxide bridging two beryllium ions and a metal coordinated hydride with some surface charge depletion. On the (100) surface, water dissociates into a hydroxide ligating a Be atom and a proton coordinated to a surface oxygen but the lowest energy water state on the (100) surface is the undissociated metal-coordinated water. The (100) fully hydroxylated surface structure has a hydrogen bonding network which facilitates rapid proton shuffling within the network. The corresponding (001) hydroxylated surface is fairly open and lacks internal hydrogen bonding. This supports previous experimental interpretations of the step in water adsorption isotherms. Further, when the (100) surface is heated to 1000 K, hydroxides and protons associate and water desorbs. The more open (001)

The bioinorganic chemistry and associated immunology of chronic beryllium disease

“…Members of our team have performed theoretical studies on the different surfaces of BeO that show the exposed surface face can influence the thermodynamics significantly. 42 These studies show that the (0 0 1) face of BeO has the greatest reactivity in water, and becomes hydroxylated during the reaction. (Fig.…”

Oxygen vibrations and acoustic surface plasmon on Be(0001)

“…45,52 The presence of atomic hydrogen and hydroxyl groups on the initially oxidized Be(0001) surface is likely due to the dissociation of residual H 2 O. 6,53 In Ref. 6 it has been shown that H dissociated from H 2 O is trapped in the oxide layer.…”

ADSORPTION PROPERTIES OF N2 ON Be(0001) SURFACE: A FIRST-PRINCIPLES CALCULATION

“…5,6 And correspondingly, the adsorption and dissociation of many gases such as H 2 O, O 2 and H 2 have already been studied academically. [7][8][9][10] Considering the usages of Be surfaces and the requirements of automotive catalytic converters, a systematic study of the adsorption and dissociation of N 2 molecules on the Be surfaces is obviously needed.…”