Gold nanoclusters reveal the potential role of magnetic spins in catalytic efficiency

Recently, a team of researchers at the HEFEI Institute of Science at the Chinese Academy of Science (CAS) has continuously removed the innermost atoms and outermost electrons of gold nanoparticles without disturbing the overall structure. This precise operation allowed us to investigate how the magnetic spin of the material affects catalytic activity.

The work was published in Science Advances, led by Professor Wu Ji-kun and collaborated with Professor Yang from CAS’s Institute of Process Engineering and Professor Tan from Jeong-Gin University.

Gold nanoclusters – Small particles consisting of hundreds to hundreds of gold atoms are ideal models for studying how atomic structure affects material properties. However, tuning the structure of such cluster atoms with atoms has long been a major challenge, especially when it is relatively large and complex.

To overcome this problem, the team developed a new synthetic method to stabilize the golden clusters of multishell using a mixture of thiols and iodine ligands: (AU127I4(TBBT)48). Here, TBBT is a bulky sulfur-containing molecule. The introduction of additional thiols then allowed them to gently “pick” a single gold atom at the very center of the structure, such as removing the peas from the middle of the nested doll without disrupting the surrounding shell. This created a new stable cluster: AU126I4(TBBT)48, which is magnetic.

Furthermore, by carefully oxidizing this structure, the researchers created a third version: (AU126I4(TBBT)48)+ regained paramagneticity. In fact, the team demonstrated the ability to accurately change the magnetic state of a material by continuously removing one atom and one electron.

Using this set of clusters, researchers were able to study how the distribution of magnetic spins changed across structures. They found that when the central atoms are removed and the particles are oxidized, the spin density shifts outward. Even more interesting, spins tend to concentrate more on iodine atoms than sulfur atoms, indicating that spins can play an important role in regulating catalytic properties.

To test this idea, the team evaluated how well each version of the gold nanocluster catalyzes the reduction of carbon dioxide. This is a response to growing interest in clean energy research. The diamagnetic version (AU126I4) achieves nearly 100% farada efficiency at relatively low voltages, and is superior to its paramagnetic counterpart. This result strongly supports the idea that magnetic spin plays an important role in catalysts.

“Our findings provide important insight into how spin affects catalyst behavior,” Professor Wu said. “This could open up new strategies for designing multifunctional materials at the atomic level.”