KAIST: "The Paradox of Nanoparticles... The More Metals Mixed, the More Uniform They Become"

A new study has overturned the long-held belief in the field of nanomaterials that mixing multiple metals destroys structural integrity. The key finding is that when different metals are combined, the competitive reactivity among metal elements enables the formation of a uniform atomic structure. The principle is that metal atoms formed first act as a kind of 'stepping stone,' lowering the energy barrier for other metal atoms to bond.

(From left) Jisoo Yoon, PhD candidate, Department of Bio and Chemical Engineering at KAIST; Jinwon Oh, PhD, Department of Materials Science and Engineering at Stanford University; Heetae Jung, Chair Professor, Department of Bio and Chemical Engineering at KAIST; Matteo Cargnello, Professor, Department of Chemical Engineering at Stanford University. KAIST

KAIST announced on May 8 that a research team led by Heetae Jeong, endowed professor in the Department of Bio and Chemical Engineering at KAIST, and a team led by Professor Matteo Cargnello from Stanford University have, for the first time, elucidated this kind of 'paradoxical phenomenon.'

Nanoparticles are widely used as key materials in advanced industries such as semiconductors, eco-friendly energy, and biotechnology. Recently, there has been a trend toward developing multi-component structures by mixing various kinds of metals to enhance performance.

However, different reaction rates for each element make it difficult to precisely control the size and shape of the particles, which is considered a major challenge in realizing multi-component structures.

The joint research team focused on 'composition focusing' as a clue to address this issue. Composition focusing refers to the phenomenon where, as more metals are mixed, the composition naturally organizes into a specific arrangement. By leveraging this, even as the number of metal elements increases, the composition of the particles can converge in a single direction and become uniform.

In practice, during the competitive combination of different metal atoms, the atoms that settle first act as stepping stones, enabling subsequently added atoms to mix more easily. Instead of atoms mixing randomly, they stack in an orderly, layered fashion to complete a stable structure.

Conceptual diagram of multicomponent nanoparticle formation and hydrogen catalyst application using competitive reactivity (AI-generated image). KAIST

The joint research team's findings are significant in that they reveal a new principle: the 'complex chemical reaction environment,' previously considered a major obstacle in nanomaterial synthesis, can actually help atoms form organized structures. The most notable achievement is the demonstration that even complex nanomaterials composed of various metals can be 'precisely designed into desired forms.'

In particular, using the same principle, the team fabricated a multi-component nanoparticle catalyst containing five different metals. This catalyst showed approximately four times higher efficiency in ammonia decomposition reactions for hydrogen production compared to conventional ruthenium catalysts (currently the most widely used in industry). It also maintained structural stability at 900 degrees Celsius, demonstrating excellent heat resistance.

Professor Jeong stated, "This research is significant in that it discovered an unexpected 'paradoxical phenomenon' during the nanoparticle synthesis process and clarified its operating principle. By applying this principle, it should be possible to design metal compositions tailored to desired performance, paving the way for the development of high-performance catalysts and eco-friendly energy materials."

Meanwhile, Jinsoo Yoon, PhD student at KAIST, and Jinwon Oh, PhD at Stanford University, participated as co-first authors, while Professor Jeong and Professor Matteo Cargnello at Stanford University served as co-corresponding authors. The research results were published on May 7 in the international journal Science.

This content was produced with the assistance of AI translation services.