"Magic" Sinter-Resistant Cluster Sizes of Pt Supported on Alumina.

Subnano cluster catalysts, while highly promising due to unique activity, selectivity, and atom-efficiency, are limited in wider applications, as they are prone to deactivation via sintering. Even size-selection, which was previously shown to reduce sintering of nanoparticles, cannot reduce the sintering of highly fluxional subnano clusters due to their inherent isomeric diversity. Here, we use a combination of theory and experiment to show that Pt clusters on AlO exhibit size-dependent sintering resistance.

Ensemble representation of catalytic interfaces: soloists, orchestras, and everything in-between.

Catalytic systems are complex and dynamic, exploring vast chemical spaces on multiple timescales. In this perspective, we discuss the dynamic behavior of fluxional, heterogeneous thermal and electrocatalysts and the ensembles of many isomers which govern their behavior. We develop a new paradigm in catalysis theory in which highly fluxional systems, namely sub-nano clusters, isomerize on a much shorter timescale than that of the catalyzed reaction, so macroscopic properties arise from the thermal ensemble of isomers, not just the ground state.

Theoretical Perspective on Spectroscopy of Fluxional Nanocatalysts.

Improvements in spectroscopy have enabled the catalysis community to investigate the dynamic nature of catalysts under operating conditions with increasing detail. Still, the highly dynamic nature of some catalysts, such as fluxional supported subnano clusters, presents a formidable challenge even for the most state-of-the-art techniques. The reason is that such fluxional catalytic interfaces contain a variety of thermally accessible states.

When Fluxionality Beats Size Selection: Acceleration of Ostwald Ripening of Sub-Nano Clusters.

Size selection was demonstrated to suppress Ostwald ripening of supported catalytic nanoparticles. When the supported clusters are subnanometer in size and highly fluxional, such as Pt clusters on the rutile TiO (110) surface, this paradigm breaks down, and the established theory of sintering needs a revision. At temperatures characteristic of catalysis (i.

CO Hydrogenation to Formate and Formic Acid by Bimetallic Palladium-Copper Hydride Clusters.

Mass spectrometric analysis of the anionic products of interaction between bimetallic palladium-copper tetrahydride anions, PdCuH, and carbon dioxide, CO, in a reaction cell shows an efficient generation of the PdCuCOH intermediate and formate/formic acid complexes. Multiple structures of PdCuH and PdCuCOH are identified by a synergy between anion photoelectron spectroscopy and quantum chemical calculations. The higher energy PdCuH isomer is shown to drive the catalytic hydrogenation of CO, emphasizing the importance of accounting for higher energy isomers for cluster catalytic activity.