Is There Anything Stronger Than Graphene?

By Ibtisam AbbasiReviewed by Lexie CornerMar 19 2025

Graphene is often regarded as one of the strongest known materials. It is about 200 times stronger than steel while remaining exceptionally lightweight and flexible.¹

Despite these advantages, graphene has limitations that affect its large-scale applications. Researchers are exploring alternative materials that offer comparable or superior mechanical properties. Some of these materials exist only in theoretical models, while others have been synthesized in laboratories.

Image Credit: Marco de Benedictis/Shutterstock.com

How does graphene compare to these emerging materials, and could any of them prove to be even stronger? This article examines some of the most promising contenders for its title.

Graphene: Strengths and Limitations

Graphene consists of a single layer of carbon atoms arranged in a hexagonal lattice, with a carbon-carbon bond length of 0.142 nm. Its strong sp² covalent bonding gives it exceptional in-plane strength and stiffness.

Experimental studies, including those by Hone et al., have measured its tensile strength at approximately 130 GPa, making it significantly stronger than steel.² It is also highly stretchable, with an elongation limit of 15–25 %, which enhances its mechanical resilience.³

However, graphene has key drawbacks. Its low bending rigidity makes it prone to out-of-plane deformations, meaning it can buckle or fold under certain conditions. Additionally, it is susceptible to cracking, which can limit its structural reliability.⁴

Large-scale production remains a challenge, as synthesizing high-quality, defect-free graphene sheets is both complex and costly. These factors have led scientists to explore alternative materials with potentially greater strength, stability, or manufacturability.

So, What Are the Alternatives to Graphene?

Carbyne

Carbyne is a one-dimensional chain of carbon atoms held together by sp-hybridized bonds, making it one of the most theoretically stiff and strong materials ever proposed. Its tensile stiffness is estimated to exceed that of graphene and carbon nanotubes by more than 200 %.

Experimental studies suggest that carbyne has a specific strength of approximately 7.5 × 10⁷ N·m/kg and requires a force of 10 nN to break a single atomic bond in the chain.⁵ Its tensile strength is estimated at 270 GPa, with a Young’s modulus of around 3 TPa, values that significantly exceed those of graphene.⁶

However, despite its impressive mechanical properties, carbyne remains highly unstable under normal conditions. The extreme reactivity of its atomic chain makes it difficult to synthesize and integrate into practical applications.

Researchers are exploring ways to stabilize carbyne and incorporate it into high-strength nanocomposites for potential use in automotive, biomedical, and aerospace industries. If these challenges can be overcome, carbyne-based materials could offer an ultralight yet exceptionally strong alternative to graphene.

Graphyne

Graphyne is a carbon allotrope that consists of both sp and sp² hybridized bonds. It forms when acetylenic groups (–C≡C–) partially or fully replace carbon-carbon bonds in graphene.

Graphyne and its related materials, known as graphyne-family members, have gained attention due to their thermomechanical properties and tunable electronic behavior. Additionally, some graphyne synthesis methods are considered more environmentally friendly compared to other advanced carbon materials.

Compared to graphene, graphyne has lower in-plane stiffness and atomic mass density. Its Poisson’s ratio—which describes how a material deforms in directions perpendicular to applied stress—ranges from 0.4 to 0.9, significantly higher than graphene’s. This suggests that graphyne is more flexible but also less rigid.

While graphyne is stronger than most polymer-based materials, its ultimate strength remains lower than graphene. However, its unique structure and tunable mechanical properties make it an interesting candidate for future applications in electronics, nanomechanics, and flexible materials.⁷

Borophene

Borophene is a two-dimensional (2D) allotrope of boron that was first synthesized in 2015 using chemical vapor deposition (CVD). This process involves depositing hot boron atoms onto a cooled silver surface, allowing them to form an atomically thin sheet.

Experimental studies suggest that borophene surpasses graphene in both strength and flexibility.⁸ Its bonding structure can be tuned during synthesis, allowing researchers to adjust its mechanical and electronic properties depending on the application. Unlike graphene, borophene has a higher Young’s modulus and greater out-of-plane strength, making it more resistant to bending and deformation.

Borophene also possesses distinct electrical properties that set it apart from graphene and other 2D materials. Studies have shown that borophene exhibits Dirac-Fermi behavior and superconductivity. Its exceptional electrochemical performance has also drawn interest for use in high-capacity batteries and supercapacitors.⁹

Diamond Nanothreads

Diamond nanothreads are a one-dimensional (1D) carbon allotrope synthesized using a benzene precursor. Their structure consists of long carbon chains arranged in a tetrahedral configuration, stabilized by strong sp³ covalent bonding.¹⁰ This unique structure gives them exceptional mechanical strength while maintaining a lightweight form.

The solid state reaction of benzene under high pressure to form ultrathin-1D nanothreads imparts them with ultra-high strength. Experimental studies have shown diamond nanothreads to have a hollow tubular structure with Stone-Wales (SW) transformation defects.

Diamond nanothreads have been reported to have an outstanding stiffness of approximately 850 GPa, along with an experimentally verified bending rigidity of 5.35 × 10^-28 N·m². Researchers have also found that modulating the concentration of SW defects allows control over the material’s brittleness and mechanical behavior.¹¹

Tetrahedral Amorphous Carbon

Tetrahedral amorphous carbon (ta-C) is a non-crystalline form of carbon produced using cathodic vacuum arc (CVA) deposition. Unlike traditional amorphous carbon, ta-C primarily consists of sp³ bonding. This gives it properties similar to diamond-like carbon (DLC) but with higher hardness and improved mechanical stability.¹²

Coatings made from ta-C are corrosion-resistant and biocompatible, making them useful in the biomedical industry, particularly for electrode coatings in biomolecule detection.

Its low production cost, scalability, and semiconducting properties, along with its tunable band-gap, make ta-C a practical material for industrial applications.

Metallic Hydrogen

Metallic hydrogen is believed to be a major component of Jovian planets and is thought to play a role in the formation of planetary magnetic fields. Theoretical predictions from the 1970s suggested that hydrogen could transition into a metallic state under extreme pressure, estimated at 250,000 atm (25 GPa).

Modern experiments have refined this estimate, showing that the transition from molecular to metallic hydrogen occurs at pressures between 45 and 500 GPa. At these pressures, molecular hydrogen becomes semiconducting and absorbs light, giving it a darkened appearance.¹³

The mechanical properties of metallic hydrogen, including its tensile strength, remain difficult to measure. However, it is expected that the strong atomic bonding under extreme pressure gives it high strength and low density, making it a potential candidate for lightweight structural materials.¹⁴

Beyond its mechanical properties, metallic hydrogen is considered a promising high-energy rocket fuel. If it can be stabilized, it could enable single-stage rockets, potentially lowering costs and advancing space exploration technologies.

Download your PDF copy now!

Strength vs. Practicality: Choosing the Right Material

Determining whether any material is truly stronger than graphene depends on more than just tensile strength. While some materials exceed graphene in specific mechanical properties, other factors—such as stability, manufacturability, and integration into existing technologies—are equally important.

There is no single "best" material, as the ideal choice depends on the application. For electronics and superconductors, borophene and tetrahedral amorphous carbon stand out due to their tunable bandgaps and electrical properties.

Among structural materials, diamond nanothreads appear to be the most promising contender. They offer high strength, stiffness, and lightweight properties, while being more feasible to produce than other ultra-strong materials. The ability to synthesize diamond nanothreads from benzene precursors in a controlled, scalable manner makes them attractive for industrial applications.

However, while carbyne and graphyne exhibit superior theoretical strength, they face major stability challenges that limit their practical use. Similarly, metallic hydrogen requires extremely high pressures to exist, making it impractical for everyday applications.

Ultimately, no single material can fully replace graphene across all applications. However, ongoing research in materials science and nanotechnology is leading to the development of new materials that could one day surpass graphene in both strength and real-world usability.

For more insights on 2D materials and their emerging applications, please visit:

• Is Molybdenum Disulfide (MoS2) a Serious Rival to Graphene?
• What Are Boron Nitride Nanotubes?
• Researchers Develop a Stronger Alternative to Graphene
• The Role of Nanosponges in Oil Spill Cleanup
• Enhancing Li-Ion Battery Performance with Carbon Nanocoatings

References and Further Reading

1. Chao, J. (2016). Graphene is Strong, But Is It Tough? Lawrence Berkeley National Laboratory. United States Department of Energy. [Online]. Available at: https://newscenter.lbl.gov/2016/02/08/graphene-is-strong-but-is-it-tough/ [Accessed on: February 27, 2025].
2. Lee, C. et. al. (2008). Measurement of the elastic properties and intrinsic strength of monolayer graphene. science, 321(5887), 385-388. Available at: https://doi.org/10.1126/science.1157996
3. Khan, Z. et. al. (2017). Mechanical and electromechanical properties of graphene and their potential application in MEMS. Journal of Physics D: Applied Physics, 50(5), 053003. Available at: https://www.doi.org/10.1088/1361-6463/50/5/053003
4. Yujie, W. et. al. (2019). Nanomechanics of graphene. National Science Review. 6(2). 324–348. Available at: https://doi.org/10.1093/nsr/nwy067
5. Liu, M. et. al. (2013). Carbyne from first principles: chain of C atoms, a nanorod or a nanorope. ACS nano, 7(11), 10075-10082. Available at: https://doi.org/10.48550/arXiv.1308.2258
6. Muller, S. et. al. (2019). Carbyne as a fiber in metal-matrix nanocomposites: A first principle study. Computational Materials Science, 159, 187-193. Available at: https://doi.org/10.1016/j.commatsci.2018.12.006
7. Kang, J. et. al. (2018). Graphyne and its family: recent theoretical advances. ACS applied materials & interfaces, 11(3), 2692-2706. Available at: https://doi.org/10.1021/acsami.8b03338
8. Wang, Z. et. al. (2019). Review of borophene and its potential applications. Frontiers of Physics, 14(3), 33403. Available at: https://doi.org/10.48550/arXiv.1903.11304
9. Ou, M. et. al. (2021). The emergence and evolution of borophene. Advanced Science, 8(12), 2001801. Available at: https://doi.org/10.1002/advs.202001801
10. Roman, R. et. al. (2015). Mechanical properties and defect sensitivity of diamond nanothreads. Nano letters, 15(3), 1585-1590. Available at: https://doi.org/10.1021/nl5041012
11. Zhan, H. et al. (2017). The best features of diamond nanothread for nanofibre applications. Nat Commun 8, 14863. Available at: https://doi.org/10.1038/ncomms14863
12. Xu, S. et. al. (1997). Mechanical properties and Raman spectra of tetrahedral amorphous carbon films with high sp3 fraction deposited using a filtered cathodic arc. Philosophical Magazine B, 76(3), 351-361. Available at: https://doi.org/10.1080/01418639708241099
13. Silvera, I. et. al. (2018). Metallic hydrogen. Journal of Physics: Condensed Matter. 30(25). 254003. Available at: https://www.doi.org/10.1088/1361-648X/aac401
14. Nellis, W. (1998). Metastable Solid Metallic Hydrogen. Philosophical Magazine. Lawrence Livermore National Laboratory. University of California. UCRL-JC-132. Available at: https://www.osti.gov/servlets/purl/2791

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.