Roadmap on exsolution for energy applications

Abstract

Over the last decade, exsolution has emerged as a powerful new method for decorating oxide supports with uniformly dispersed nanoparticles for energy and catalytic applications. Due to their exceptional anchorage, resilience to various degradation mechanisms, as well as numerous ways in which they can be produced, transformed and applied, exsolved nanoparticles have set new standards for nanoparticles in terms of activity, durability and functionality. In conjunction with multifunctional supports such as perovskite oxides, exsolution becomes a powerful platform for the design of advanced energy materials. In the following sections, we review the current status of the exsolution approach, seeking to facilitate transfer of ideas between different fields of application. We also explore future directions of research, particularly noting the multi-scale development required to take the concept forward, from fundamentals through operando studies to pilot scale demonstrations.

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO2 Reforming of Methane

“…Moreover, considering the application and long-term testing of these samples, Ir-B 0.9 TO decomposition could lead to instability during operation. This has been reported in the majority of the literature studies for similar systems where phase decomposition and exsolution occurred simultaneously; ,− hence, Ir-BTO was chosen for further testing and investigation.…”

“…The most commonly studied metals for the DRM reaction are Ni and Co, mainly due to their low cost and high activity for this specific reaction. ,, However, these are both highly prone to deactivation by sintering and carbon deposition. ,, A partial solution to such issues would be in the use of noble metals, which have improved resistance to coke formation as well as activity and selectivity to syngas production. − However, the high temperatures required to reach an appreciable activity and conversion often cause mobility and sintering of the active species on the support surface, especially when catalysts are developed via traditional synthesis methods such as vapor deposition or chemical infiltration. , Therefore, a promising approach called “exsolution” has recently gathered interest due to its intrinsic characteristics of ease of synthesis and stability of the produced nanoparticles during catalytic application. − In such a method, instead of having the catalytic nanoparticles deposited on the surface of the support, the catalytic species is incorporated into the structure of a host during initial materials synthesis, to then diffuse from the solid solution to the surface of the support via a reduction treatment (or through the application of an electrical potential or plasma treatment) ,− in the form of “socketed” metallic nanoparticles. This results in the often observed exsolved materials’ unique stability to carbon deposition and sintering. , Moreover, recent studies have also highlighted the role of the socketing, and consequent strain achieved between exsolved NPs and the support, in the enhanced catalytic activities measured for several processes, such as CO oxidation, CO 2 reduction in solid oxide cells, and also CH 4 /CO 2 conversion. ,,,− Moreover, exploring the use of alkaline earth A-site perovskite oxides as supports might be beneficial due to their structural stability, the introduction of basic sites, which is known to promote surface reactions, and their lattice oxygen mobility, which could lead to the possible introduction of oxygen vacancies. These factors are all regarded as important in the activity observed for the DRM reaction. ,, …”

A kinetic study on oxygen redox reaction of a double-perovskite reversible oxygen electrode—Part I: Experimental analysis

“…Nevertheless, considering the simple electrode architecture proposed in this work (i.e. slurry coated), SBCCO performance is likely to be improved by electrode architecture engineering with the incorporation of a composite electrode [37], exsolved nanoparticles [38,39] or electrocatalyst infiltration [40].…”

Co-Exsolution of Ni-Based Alloy Catalysts for the Valorization of Carbon Dioxide and Methane

“…The separation of a solid phase from a homogeneous solid solution, known as exsolution, is a fascinating phenomenon with wide-ranging applications in geology, chemistry, − and materials engineering . In the field of catalysis, exsolution is being explored to create “smart” or “intelligent” nanocatalysts with improved sinter resistance, coke resistance, and impurity resistance. ,− The exsolved catalyst nanoparticles are formed under a reducing environment (Figure a) and can regenerate after exposure to an oxidizing environment, making them highly advantageous in energy-intensive reactions. − ,, Their unique properties of improved dispersion, thermal stability, and compositional malleability compared to those of conventional synthesis strategies (Figure b) are particularly useful for valorizing CO 2 into chemical commodities and fuels.…”