New catalyst developed from nanoscale cubes

New catalyst developed from nanoscale cubes
by Riko Seibo
Tokyo, Japan (SPX) Aug 01, 2024

Researchers from Tokyo Metropolitan University have created innovative sheets of transition metal chalcogenide "cubes" linked by chlorine atoms. Unlike the widely studied atom-based sheets such as graphene, the team's research introduces the novel use of clusters. They successfully formed nanoribbons within carbon nanotubes for structural analysis and also created microscale sheets of cubes, which were exfoliated and examined. These sheets demonstrated exceptional catalytic properties for hydrogen production.

Two-dimensional materials have revolutionized nanotechnology, offering unique electronic and physical properties due to their sheet-like structures. While graphene is a prominent example, transition metal chalcogenides (TMCs), consisting of a transition metal and a group 16 element like sulfur or selenium, have also garnered significant attention. TMC nanosheets have been shown to emit light and function effectively as transistors.

Despite rapid advancements, most research has focused on achieving the correct crystalline structure in sheet-like geometries. A team led by Assistant Professor Yusuke Nakanishi at Tokyo Metropolitan University explored a different method: using TMC clusters to form two-dimensional patterns. This novel approach to assembling nanosheets could lead to a new class of nanomaterials.

The researchers concentrated on cubic "superatomic" clusters of molybdenum and sulfur. They synthesized their material from a vapor of molybdenum (V) chloride and sulfur within the nanoscale confines of carbon nanotubes. The resulting nanoribbons were well-isolated and clearly imaged using transmission electron microscopy (TEM). They confirmed that the material comprised isolated molybdenum sulfide "cubes" connected by chlorine atoms, distinct from cubic structures in bulk materials.

To make the material viable for practical applications, it needs to be produced in larger dimensions. In the same experiment, the team found a flaky material coating the inside of their glass reaction tube. Upon separating the solid from the tube walls, they discovered it was composed of relatively large microscale flakes made of the same superatomic clusters arranged in a hexagonal pattern.

The team has just begun exploring the potential of their new material. Theoretically, they have shown that the same structure under tiny stresses could emit light. They also discovered that it might serve as an effective catalyst for the hydrogen evolution reaction (HER), which occurs when hydrogen is generated as a current passes through water. Compared to molybdenum disulfide, a promising catalytic material, the new layered material exhibited significantly higher current at lower voltages, indicating greater efficiency.

While further research is needed, this innovative approach to assembling nanosheets holds the promise of developing a variety of new materials with exciting functions.

Research Report:Superatomic layer of cubic Mo4S4 clusters connected by Cl cross-linking