Titanium dioxide is a promising candidate for photocatalytic H₂ fuel production, and understanding water splitting on TiO₂ surfaces is vital toward explaining and improving the generation of H₂. In this work, we electron irradiate anatase TiO₂(101) at room temperature to create metastable surface oxygen vacancies in order to investigate their ability to dissociate H₂O. Our scanning tunneling microscopy investigations suggest that the surface oxygen vacancies can dissociate H₂O by forming bridging OH species. This claim is supported by theoretical calculations from the literature and our previously published spectroscopic measurements.

We report here in situ measurements of the evolution of the Ag(110) surface during Si growth, using scanning tunneling microscopy and grazing incidence x-ray diffraction. We provide compelling evidence of an Ag(110) surface reconstruction associated with the release of Ag atoms induced by the growth of Si nanoribbons. Our results are in agreement with a missing row reconstruction of the Ag layer underneath the nanoribbons. This challenges the current understanding of the Si growth on nonreconstructed Ag(110), interpreted within the framework of silicene models.

Elucidating the structure of the interface between natural (reduced) anatase TiO₂ (101) and water is an essential step towards understanding the associated photo-assisted water splitting mechanism. Here we present surface X-ray diffraction results for the room temperature interface with ultra-thin and bulk water, which we explain by reference to density functional theory calculations. We find that both interfaces contain a 25:75 mixture of molecular H₂O and terminal OH bound to titanium atoms along with bridging OH species in the contact layer. This is in complete contrast to the inert character of room temperature anatase TiO₂ (101) in ultra-high vacuum. A key difference between the ultra-thin and bulk water interfaces is that in the latter, water in the second layer is also ordered. These molecules are hydrogen bonded to the contact layer, modifying the bond angles.

Scanning tunneling microscopy (STM) and grazing-incidence x-ray diffraction (GIXD) have been used to follow in situ the growth and the structure of Au-Cu nanoparticles (NPs) formed on $\mathrm{Ti}{\mathrm{O}}_2$(110) by successive metal evaporations. STM observations of the same area of the substrate highlight the strong dependence between the sequence of deposition and the final result. Deposition of Cu first leads to a system where both Au-Cu and pure Au NPs coexist. Deposition of Au first ensures growing mostly bimetallic NPs. GIXD results show that Cu alloys instantaneously with Au NPs at room temperature. Similar observations during evaporation of Au on Cu NPs show that some of the Au atoms alloy with Cu whereas the rest remain at the NP shell. This is attributed both to kinetics and thermodynamics origins.

Combining X-ray photoelectron spectroscopy with the standing wave technique we investigated adsorption of a monolayer of water on Ti-oxide terminated SrTiO3(001) in ultra-high vacuum (UHV). At room temperature, the surface is water free but hydroxylated. A quarter monolayer of hydroxyl is tightly bound (1.85 ± 0.06) Å above the TiO2 surface. Deposited at low temperature, a monolayer of water adsorbs with the oxygen located (2.55 ± 0.2) Å above the surface, apparently close to atop Ti, but H2O is unstable at 200K. A fraction desorbs, in part under the X-ray beam, but a major fraction of H2O dissociates immediately, with the liberated hydrogen most likely attaching to a surface oxygen. The produced hydroxyls bind only loosely to the surface, are unstable at 200K and rapidly desorb once the surface is water-free. Although our study was conducted in UHV, the presented results suggests that Ti-oxide terminated SrTiO3(001) may possess a high catalytic activity toward hydrolysis under realistic conditions.