Surface composition of AgPd single-atom alloy catalyst in an oxidative environment.

Single-atom alloys (SAAs) have recently gained considerable attention in the field of heterogeneous catalysis research due to their potential for novel catalytic properties. While SAAs are often examined in reactions of reductive atmospheres, such as hydrogenation reactions, in the present work, we change the focus to AgPd SAAs in oxidative environments since Pd has the highest catalytic activity of all metals for oxidative reactions. Here, we examine how the chemical reactivity of AgPd SAAs differs from its constituent Pd in an oxidative atmosphere.

Isolated Pd atoms in a silver matrix: Spectroscopic and chemical properties.

Over the past decade, single-atom alloys (SAAs) have been a lively topic of research due to their potential for achieving novel catalytic properties and circumventing some known limitations of heterogeneous catalysts, such as scaling relationships. In researching SAAs, it is important to recognize experimental evidence of peculiarities in their electronic structure. When an isolated atom is embedded in a matrix of foreign atoms, it exhibits spectroscopic signatures that reflect its surrounding chemical environment.

In situ observation of oscillatory redox dynamics of copper.

How a catalyst behaves microscopically under reaction conditions, and what kinds of active sites transiently exist on its surface, is still very much a mystery to the scientific community. Here we present an in situ study on the red-ox behaviour of copper in the model reaction of hydrogen oxidation. Direct imaging combined with on-line mass spectroscopy shows that activity emerges near a phase boundary, where complex spatio-temporal dynamics are induced by the competing action of simultaneously present oxidizing and reducing agents.

Formation of a 2D Meta-stable Oxide by Differential Oxidation of AgCu Alloys.

Metal alloy catalysts can develop complex surface structures when exposed to reactive atmospheres. The structures of the resulting surfaces have intricate relationships with a myriad of factors, such as the affinity of the individual alloying elements to the components of the gas atmosphere and the bond strengths of the multitude of low-energy surface compounds that can be formed. Identifying the atomic structure of such surfaces is a prerequisite for establishing structure-property relationships, as well as for modeling such catalysts in ab initio calculations.

One-pot versus sequential reactions in the self-assembly of gigantic nanoscale polyoxotungstates.

By using a new type of lacunary tungstoselenite {Se(2)W(29)O(103)} (1), which contains a "defect" pentagonal {W(W)(4)} unit, we explored the assembly of clusters using this building block and demonstrate how this unit can give rise to gigantic nanomolecular species, using both a "one-pot" and "stepwise" synthetic assembly approach. Specifically, exploration of the one-pot synthetic parameter space lead to the discovery of {Co(2.5)(W(3.

Assembly of molecular "layered" heteropolyoxometalate architectures.

Neoclassical architecture: A new family of heteropolyoxometalates with "pagoda"-shaped building blocks [Te(n)W(6n+3)O(21n+12)]((6+2n)-) (n=1, 2, 3) was discovered by adding {TeW(6)O(21)} layers on a classic {TeW(9)O(33)} fragment. Linking of the units allowed the generation of nanostructured clusters whose gross conformation is cation controlled. Studies of the redox behaviors of the multi-layered clusters indicate that the Te(IV) template is redox-active.