‘Hopelessly attached’: Scientists discover new 2D material that sticks the landing

HOUSTON – (May 23, 2025) – More than ten years ago, researchers at Rice University led by materials scientist Boris Yakobson predicted that boron atoms would cling too tightly to copper to form borophene, a flexible, metallic two-dimensional material with potential across electronics, energy and catalysis. Now, new research shows that prediction holds up, but not in the way anyone expected.

Unlike systems such as graphene on copper, where atoms may diffuse into the substrate without forming a distinct alloy, the boron atoms in this case formed a defined 2D copper boride ⎯ a new compoundwith a distinct atomic structure. The finding, published in Science Advances by researchers from Rice and Northwestern University, sets the stage for further exploration of a relatively untapped class of 2D materials.

“Borophene is still a material at the brink of existence, and that makes any new fact about it important by pushing the envelope of our knowledge in materials, physics and electronics,” said Yakobson, Rice’s Karl F. Hasselmann Professor of Engineering and professor of materials science and nanoengineering and chemistry. “Our very first theoretical analysis warned that on copper, boron would bond too strongly. Now, more than a decade later, it turns out we were right ⎯ and the result is not borophene, but something else entirely.”

Previous studies successfully synthesized borophene on metals like silver and gold, but copper remained an open ⎯ and contested ⎯ case. Some experiments suggested boron might form polymorphic borophene on copper, while others suggested it could phase-separate into borides or even nucleate into bulk crystals. Resolving these possibilities required a uniquely detailed investigation combining high-resolution imaging, spectroscopy and theoretical modeling.

“What my experimentalist colleagues first saw were these rich patterns of atomic resolution images and spectroscopy signatures, which required a lot of hard work of interpretation,” Yakobson said.

These efforts revealed a periodic zigzag superstructure and distinct electronic signatures, both of which deviated significantly from known borophene phases. A strong match between experimental data and theoretical simulations helped resolve a debate about the nature of the material that forms at the interface between the copper substrate and the near-vacuum environment of the growth chamber.

Although copper boride was not the material researchers set out to make, its discovery offers important insight into how boron interacts with different metal substrates in two-dimensional environments. The work expands the knowledge on the formation of atomically thin metal boride materials ⎯ an area that could inform future studies of related compounds, including those with known technological relevance, such as metal borides among ultra-high temperature ceramics, which are of great interest for extreme environments and hypersonic systems.

“2D copper boride is likely to be just one of many 2D metal borides that can be experimentally realized. We look forward to exploring this new family of 2D materials that have broad potential use in applications ranging from electrochemical energy storage to quantum information technology,” said Mark Hersam , Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University, who is a co-corresponding author on the study.

The discovery comes shortly after another boron-related breakthrough by the same Rice theory team. In a separate study published in ACS Nano , researchers showed that borophene can form high-quality lateral, edge-to-edge junctions with graphene and other 2D materials, offering better electrical contact than even “bulky” gold. The juxtaposition of the two findings highlights both the promise and the challenge of working with boron at the atomic scale: its versatility allows for surprising structures but also makes it difficult to control.

“Those images we initially saw in the experimental data looked quite mysterious,” Yakobson said. “But in the end, it all fell into place and provided a logical answer ⎯ metal boride, bingo! This was unexpected at first, but now, it is settled ⎯ and the science can move forward.”

The research was supported by the Office of Naval Research (N00014-21-1-2679), the National Science Foundation (DMR-2308691) and the United States Department of Energy (2801SC0012547). The content herein is solely the responsibility of the authors and does not necessarily represent the official views of the funding organizations and institutions.

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This news release can be found online at news.rice.edu.

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Peer-reviewed papers:

Atomic-resolution structural and spectroscopic evidence for the synthetic realization of two-dimensional copper boride | Science Advances | DOI: 10.1126/sciadv.adv8385
Authors: Hui Li, Qiyuan Ruan, Cataldo Lamarca, Albert Tsui, Boris Yakobson and Mark Hersam
https://doi.org/10.1126/sciadv.adv8385

Electron transport in borophene–graphene lateral edge–edge junctions | ACS Nano | DOI: 10.1021/acsnano.4c09843
Yuefei Huang, Henry Yu, Favian Sun, Qiyuan Ruan and Boris Yakobson
https://pubs.acs.org/doi/10.1021/acsnano.4c09843

About Rice:

Located on a 300-acre forested campus in Houston, Texas, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of architecture, business, continuing studies, engineering and computing, humanities, music, natural sciences and social sciences and is home to the Baker Institute for Public Policy. Internationally, the university maintains the Rice Global Paris Center, a hub for innovative collaboration, research and inspired teaching located in the heart of Paris. With 4,776 undergraduates and 4,104 graduate students, Rice’s undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 7 for best-run colleges by the Princeton Review. Rice is also rated as a best value among private universities by the Wall Street Journal and is included on Forbes’ exclusive list of “New Ivies.”