Water Structures Reveal Local Hydrophobicity on the In₂O₃(111) Surface

Abstract

Clean oxide surfaces are generally hydrophilic. Water molecules anchor at undercoordinated surface metal atoms that act as Lewis acid sites, and they are stabilized by H bonds to undercoordinated surface oxygens. The large unit cell of In2O3(111) provides surface atoms in various configurations, which leads to chemical heterogeneity and a local deviation from this general rule. Experiments (TPD, XPS, nc-AFM) agree quantitatively with DFT calculations and show a series of distinct phases. The first three water molecules dissociate at one specific area of the unit cell and desorb above room temperature. The next three adsorb as molecules in the adjacent region. Three more water molecules rearrange this structure and an additional nine pile up above the OH groups. Despite offering undercoordinated In and O sites, the rest of the unit cell is unfavorable for adsorption and remains water-free. The first water layer thus shows ordering into nanoscopic 3D water clusters separated by hydrophobic pockets.

Elucidating the Mechanism of Large Phosphate Molecule Intercalation Through Graphene-Substrate Heterointerfaces

“…These two new peaks were up-shifted by 1.1 eV from the peak position of the In 2 O 3 reference (red dashed line). 75 Furthermore, a strong phosphorus signal was detected in samples intercalated with P 2 O 5 (Figure 6b). Therefore, based on these observations, we can exclude the formation of In 2 O 3 in the P 2 O 5 intercalated samples.…”

A Hydroscopic Indium Hydrogel Capturing Atmospheric Humidity for Autonomous Agriculture

“…The In 3d spectrum demonstrates the presence of In 3þ in the hydrogel. [23,24] These high-valence metal ions can be served as sorption sites to couple with nitrogen or oxygen atoms. This coupling method belongs to chemisorption, the empty electron orbitals of metallic and the lone electron pairs of nonmetallics comprise the chemical bond.…”

Effect of Different In2O3(111) Surface Terminations on CO2 Adsorption

“…14 The absence of a strongly shifted peak in the O 1s XPS spectra supports the assessment that only dissociated water is present on the surface and is in agreement with the previous STM study of water on In 2 O 3 (111), which showed that it is possible to achieve a coverage of three water molecules per In 2 O 3 (111) unit cell at room temperature. 19,44 Methanol and Formic Acid on Stoichiometric In 2 O 3 (111). To study how the methanol product and possible reaction intermediate formic acid bind to the surface, their adsorption on stoichiometric In 2 O 3 (111) was studied experimentally and computationally.…”