Nanomaterials are important in producing next-generation energy and environmental technologies, especially in developing better catalysts and microelectronics. However, achieving precise nano-engineered structures remains difficult.
In recent years, metal exsolution from oxides emerged as a promising tool in fabricating oxides fabricated with nanoparticles. It may be possible to create nanostructured oxides with new catalytic and transport properties through the exsolution process.
Conventional exsolution strategies are currently limited by their dependence on specific host metal oxides, restricting their applicability to a narrow range of materials. Because of this, there is a need to develop a more universal and oxide-independent technique for controlling exsolution.
However, experts are still faced with the challenge of controlling exsolved nanoparticles' location, composition, density, and size. This struggle limits the ultimate performance achieved by the nanostructures.
Challenges in Metal Exsolution
Electrochemical reactions involve fuel and electrolysis cells through three principal components - two electrodes separated by an electrolyte. The two cells differ from each other in terms of the reactions involved.
In such reactions, the electrodes are typically coated with catalysts or the material that speeds up the reaction without getting any permanent chemical change. Most industries use a critical catalyst composed of metal oxide, but this practice faces some challenges, such as low durability.
Manufacturers also use metal exsolution, a process that involves the precipitation of metal nanoparticles out of a host oxide onto the surface of the electrode. Since the particles embed themselves into the electrode, the anchoring makes them more stable. Because of this, evolution has led to remarkable progress in clean energy production and the development of energy-efficient computing devices.
However, experts find it challenging to control the precise properties of the resulting nanoparticles. While exsolution can give them stable and active nanoparticles, controlling it has been challenging.
Gaining Control of Nanoparticles
Researchers at the Massachusetts Institute of Technology have precisely controlled nanoparticle size, composition, and other parameters. They made this possible by leveraging ion irradiation, a process of bombarding a material with beams of charged particles.
In this study, the researchers used binary and perovskite oxide thin films as model systems. It was found that nanoparticles made this way are superior in performance over their counterparts, which are made conventionally. Since ion irradiation is an external stimulus, this method can be applied in customizing exsolution in diverse materials and not only to a particular set of oxide hosts.
The novel method does not only enable precise engineering of nanoparticles, but it also incorporates various elements for improved catalytic activity. Since ion irradiation creates electrode defects, it offers additional nucleation sites for particle growth and enables extreme spatial control over nanoparticle distribution.
Metallic nanoparticles can be catalysts in an entire reaction, including the crucial reaction of splitting water molecules to generate hydrogen atoms for energy storage. It is known that exsolution results in structurally stable nanoparticles, but since the process is not easy to control, the optimal number and size of particles are not obtained.
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