Atmosphere-dependent stability and mobility of catalytic Pt single atoms and clusters on γ-AlO.

Atomically dispersed metals promise the ultimate catalytic efficiency, but their stabilization onto suitable supports remains challenging owing to their aggregation tendency. Focusing on the industrially-relevant Pt/γ-Al2O3 catalyst, in situ X-ray absorption spectroscopy and environmental scanning transmission electron microscopy allow us to monitor the stabilization of Pt single atoms under O2 atmosphere, as well as their aggregation into mobile reduced subnanometric clusters under H2. Density functional theory calculations reveal that oxygen from the gas phase directly contributes to metal-support adhesion, maximal for single Pt atoms, whereas hydrogen only adsorbs on Pt, and thereby leads to Pt clustering.

New Lamellar Silver Thiolate Coordination Polymers with Tunable Photoluminescence Energies by Metal Substitution.

The structures of two lamellar silver thiolate coordination polymers [Ag( p-SPhCOH)] (1) and [Ag( p-SPhCOMe)] (2) are described for the first time. Their inorganic part is composed of distorted AgS honeycomb networks separated by noninterpenetrated thiolate ligands. The main difference between the two compounds arises from dimeric hydrogen bonds present for the carboxylic acids.