Advancing the synthesis of two-dimensional gold monolayers

Researchers have created nearly freestanding nanostructured two-dimensional (2D) gold monolayers, an impressive feat of nanomaterial engineering that could open up new avenues in catalysis, electronics, and energy conversion.

Gold is an inert metal which typically forms a solid three-dimensional (3D) structure. However, in its 2D form, it can unlock extraordinary properties, such as unique electronic behaviors, enhanced surface reactivity, and immense potential for revolutionary applications in catalysis and advanced electronics.

One of the challenges in synthesizing 2D gold monolayers has been stabilizing isotropic metallic bonds in strictly 2D forms. To address this, the research team at Lund University and Hokkaido University employed a novel bottom-up approach combined with high-performance computations, enabling the creation of macroscopically large gold monolayers with unique nanostructured patterns, remarkable thermal stability, and potential catalytic utility.

The team grew gold monolayers on an iridium substrate and embedded boron atoms at the interface between gold and iridium. This innovative technique produced suspended monoatomic sheets of gold, which had a hexagonal structure with nanoscale triangular patterns. Incorporating boron enhanced the stability and structural integrity of the gold layers, allowing the nanostructures to form.

“The ease of preparation and thermal stability of the resulting gold films is significant, making them a practical platform for further studies of fundamental properties of elemental 2D metals and their potential for diverse applications in electronics and nanotechnology,” explains Dr. Alexei Preobrajenski of the MAX IV Laboratory, Lund University, and a corresponding author of the study.

Advanced characterization techniques, including scanning tunneling microscopy (STM) and X-ray spectroscopy, were employed to investigate the structural and electronic properties of the gold films. The analysis confirmed that embedding boron facilitates a transition from 3D to primarily 2D metal bonding, fundamentally altering the electronic behavior of the gold layers. This transformation underscores the unique nature of the synthesized films, as traditional methods typically fail to maintain a stable 2D metallic form, leading instead to small or unstable structures.

The ability to create stable and nearly freestanding metallic monolayers over a large area has far-reaching implications. “This research opens avenues for testing theories and further exploration into the potential applications of 2D metals in the various fields, including catalysis and energy conversion,” says Associate Professor Andrey Lyalin of the Faculty of Science, Hokkaido University, and the other corresponding author of the study.

By addressing the challenges of stabilizing 2D metallic materials, this study contributes to the growing understanding of 2D materials and lays the groundwork for potential technological applications.