A newly synthesized material known as monolayer amorphous carbon (MAC), however, has demonstrated remarkable toughness-eight times greater than graphene-according to a recent study led by researchers at Rice University in collaboration with the National University of Singapore (NUS). The findings, published in *Matter*, highlight MAC's potential as a breakthrough in the development of durable 2D materials.
Like graphene, MAC consists of a single layer of carbon atoms, but its structure is fundamentally different. Unlike graphene's orderly hexagonal crystalline lattice, MAC is a nanocomposite, incorporating both crystalline and amorphous regions. This structural combination significantly enhances its ability to resist cracking and absorb energy before fracturing.
"This unique design prevents cracks from propagating easily, allowing the material to absorb more energy before breaking," explained Bongki Shin, a graduate student in materials science and nanoengineering and the study's first author.
The brittleness of 2D materials has remained a key limitation in their broader technological application, from next-generation electronics and high-capacity energy storage to advanced sensors and wearable devices. The study identifies two approaches to improving their toughness: "extrinsic toughening," which involves adding reinforcing structures to thin films, and "intrinsic toughening," which alters the material's in-plane structure. The latter approach, exemplified by MAC's composition, provides an effective strategy for enhancing durability without additional layers.
"We believe that this structure-based toughening strategy could work for other 2D materials, so this work opens up exciting possibilities for advanced materials design," said Jun Lou, professor of materials science and nanoengineering and of chemistry at Rice University, and a corresponding author of the study.
To analyze MAC's fracture resistance, Rice researchers conducted in situ tensile testing inside a scanning electron microscope, enabling real-time observation of crack formation and propagation. Additionally, computational modeling by Markus Buehler's group at the Massachusetts Institute of Technology provided atomic-scale insights into how MAC's composite structure influences fracture energy.
"This hadn't been done before because creating and imaging an ultrathin, disordered material at the atomic scale is extremely challenging," said Yimo Han, assistant professor of materials science and nanoengineering at Rice and a corresponding author on the study. "However, thanks to recent advances in nanomaterial synthesis and high-resolution imaging, we were able to uncover a new approach to making 2D materials tougher without adding extra layers."
The research was supported by the United States Department of Energy (DE-SC0018193), the Welch Foundation (C-1716, C-2065), the Singapore National Research Foundation's Competitive Research Program (NRF-CRP22-2019-008), and the Singapore Ministry of Education (MOE-T2EP50220-0017, EDUNC-33-18-279-V12). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.