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As a low‐cost alternative to noble metals, Cu plays an important role in industrial catalysis, such as water‐gas shift reaction, methanol or ethanol oxidation, hydrogenation of oils, CO oxidation, among many others. An important step in optimizing Cu catalyst performance is control of nanoparticles size, distribution, and the interface with the support. While proton conducting perovskites can enhance the metal catalytic activity when acting as the support, there has been limited investigation of in situ growth of Cu metal nanoparticles from the proton conductors and its catalytic performance. Here, Cu nanoparticles are tracked exsolved from an A‐site‐deficient proton‐conducting barium cerate‐zirconate using scanning electron microscopy, revealing a continuous phase change during exsolution as a function of reduction temperature. Combined with the phase diagram and cell parameter change during reduction, a new exsolution mechanism is proposed for the first time which provides insight into tailoring metal particles interfaces at proton conducting oxide surfaces. Furthermore, the catalytic behavior in the CO oxidation reaction is explored and, it is observed that these new nanostructures can rival state of the art catalysts over long term operation. [ABSTRACT FROM AUTHOR]

High‐performance nanoparticle platforms can drive catalysis progress to new horizons, delivering environmental and energy targets. Nanoparticle exsolution offers unprecedented opportunities that are limited by current demanding process conditions. Unraveling new exsolution pathways, particularly at low‐temperatures, represents an important milestone that will enable improved sustainable synthetic route, more control of catalysis microstructure as well as new application opportunities. Herein it is demonstrated that plasma direct exsolution at room temperature represents just such a step change in the synthesis. Moreover, the factors that most affect the exsolution process are identified. It is shown that the surface defects produced initiate exsolution under a brief ion bombardment of an argon low‐pressure and low‐temperature plasma. This results in controlled nanoparticles with diameters ≈19–22 nm with very high number densities thus creating a highly active catalytic material for CO oxidation which rivals traditionally created exsolved samples. [ABSTRACT FROM AUTHOR]

Supported bimetallic nanoparticles used for various chemical transformations appear to be more appealing than their monometallic counterparts, because of their unique properties mainly originating from the synergistic effects between the two different metals. Exsolution, a relatively new preparation method for supported nanoparticles, has earned increasing attention for bimetallic systems in the past decade, not only due to the high stability of the resulting nanoparticles but also for the potential to control key particle properties (size, composition, structure, morphology, etc.). In this review, we summarize the trends and advances on exsolution of bimetallic systems and provide prospects for future studies in this field. [ABSTRACT FROM AUTHOR]

Exsolution of surface and bulk nanoparticles in perovskites has been recently employed in chemical looping methane partial oxidation because of the emergent materials' properties such as oxygen capacity, redox stability, durability, coke resistance and enhanced activity. Here we attempt to further lower the temperature of methane conversion by complementing exsolution with infiltration. We prepare an endo/exo-particle system using exsolution and infiltrate it with minimal amount of Rh (0.1 wt%) in order to functionalize the surface and induce low temperature activity. We achieve a temperature decrease by almost 220 °C and an increase of the activity up to 40%. We also show that the initial microstructure of the perovskite plays a key role in controlling nanoparticle anchorage and carbon deposition. Our results demonstrate that microstructure tuning and surface functionalization are important aspects to consider when designing materials for redox cycling applications. [ABSTRACT FROM AUTHOR]

Particles dispersed on the surface of oxide supports have enabled a wealth of applications in electrocatalysis, photocatalysis, and heterogeneous catalysis. Dispersing nanoparticles within the bulk of oxides is, however, synthetically much more challenging and therefore less explored, but could open new dimensions to control material properties analogous to substitutional doping of ions in crystal lattices. Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within a perovskite oxide lattice as well as on its surface. By employing operando techniques, we show that in the emergent nanostructure, the endogenous nanoparticles and the perovskite lattice become reciprocally strained and seamlessly connected, enabling enhanced oxygen exchange. Additionally, even deeply embedded nanoparticles can reversibly exchange oxygen with a methane stream, driving its redox conversion to syngas with remarkable selectivity and long term cyclability while surface particles are present. These results not only exemplify the means to create extensive, self‐strained nanoarchitectures with enhanced oxygen transport and storage capabilities, but also demonstrate that deeply submerged, redox‐active nanoparticles could be entirely accessible to reaction environments, driving redox transformations and thus offering intriguing new alternatives to design materials underpinning several energy conversion technologies. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles exsolved at the surface of perovskite oxides have been recently shown to unlock superior catalytic activity and durability towards various chemical reactions of practical importance. For example, for the CO oxidation reaction, exsolved Ni nanoparticles in oxidised form exhibit site activities approaching those of noble metals. This is of particular interest for the prospect of replacing noble metals with earth-abundant metal/metal oxide catalysts in the automotive exhaust control industry. Here we show that for the CO oxidation reaction, the functionality of exsolved Ni nanoparticles can be further improved when Fe is co-exsolved with Ni, as Fe–Ni alloy nanoparticles, eventually forming mixed oxide nanoparticles. As compared to the Ni nanoparticles, the alloy nanoparticles exhibit higher site activities, greatly improved durability over 170 h of continuous testing and increased tolerance towards sulphur-based atmospheres. Similarly to the single metal nanoparticles, the alloys demonstrate outstanding microstructural stability and high tolerance towards coking. These results open additional directions for tailoring the activity and durability of exsolved materials for the CO oxidation reaction and beyond. [ABSTRACT FROM AUTHOR]