Direct Anchoring of Molybdenum Sulfide Molecular Catalysts on Antimony Selenide Photocathodes for Solar Hydrogen Production.

Molybdenum sulfide serves as an effective nonprecious metal catalyst for hydrogen evolution, primarily active at edge sites with unsaturated molybdenum sites or terminal disulfides. To improve the activity at a low loading density, two molybdenum sulfide clusters, [MoS] and [MoS], were investigated. The MoS molecular catalysts were heterogenized on SbSe with a simple soaking treatment, resulting in a thin catalyst layer of only a few nanometers that gave up to 20 mA cm under one sun illumination.

Stability of Iridium Single Atoms on FeO(001) in the mbar Pressure Range.

Stable single metal adatoms on oxide surfaces are of great interest for future applications in the field of catalysis. We studied iridium single atoms (Ir) supported on a FeO(001) single crystal, a model system previously only studied in ultra-high vacuum, to explore their behavior upon exposure to several gases in the millibar range (up to 20 mbar) utilizing ambient-pressure X-ray photoelectron spectroscopy. The Ir single adatoms appear stable upon exposure to a variety of common gases at room temperature, including oxygen (O), hydrogen (H), nitrogen (N), carbon monoxide (CO), argon (Ar), and water vapor.

Dynamic Equilibrium at the HCOOH-Saturated TiO(110)-Water Interface.

Carboxylic acids bind to titanium dioxide (TiO) dissociatively, forming surface superstructures that give rise to a (2 × 1) pattern detected by low-energy electron diffraction. Exposing this system to water, however, leads to a loss of the highly ordered surface structure. The formate-covered surface was investigated by a combination of diffraction and spectroscopy techniques, together with static and dynamic ab initio simulations, with the conclusion that a dynamic equilibrium exists between adsorbed formic acid and water molecules.

Probing the solid-liquid interface with tender x rays: A new ambient-pressure x-ray photoelectron spectroscopy endstation at the Swiss Light Source.

A new endstation to perform operando chemical analysis at solid-liquid interfaces by means of ambient pressure x-ray photoelectron spectroscopy (APXPS) is presented. The endstation is located at the Swiss Light Source and can be attached to the soft x-ray in situ spectroscopy beamline (X07DB) for solid-gas type experiments and to a tender x-ray beamline (PHOENIX I) for solid-liquid interface experiments. The setup consists of three interconnected ultrahigh vacuum chambers: one for sample preparation using surface science techniques, the analysis chamber for APXPS experiments, and an entry-lock chamber for sample transfer across the two pressure regimes.