MXene the Revolutionary 2D Material – Synthesis, Fundamentals, Applications, and Beyond
MXene, a family of two-dimensional (2D) transition metal carbides and nitrides, has recently garnered significant attention in the scientific and tech communities due to its unique combination of properties. These properties include high electrical conductivity, hydrophilicity, and exceptional mechanical strength, making MXene a promising material for a wide range of applications, such as energy storage, sensors, and more. Want to explore MXene material synthesis, fundamentals, applications, energy, pricing, fabrics, conductivity, and pronunciation? Keep reading.
MXene materials are classified as 2D transition metal carbides and nitrides, originating from the parent MAX phases. MAX phases are ternary layered ceramics, consisting of transition metals (M), group 13 or 14 elements (A), and carbon or nitrogen (X). The general formula for MXene is Mn+1XnTx, where M represents a transition metal, X represents carbon or nitrogen, and Tx represents surface functional groups such as –O, –OH, or –F.
MXenes exhibit unique properties that distinguish them from other 2D materials like graphene. These properties include:
High electrical conductivity: MXenes have demonstrated exceptional in-plane electrical conductivity, which is vital for applications in electronics and energy storage.
Hydrophilicity: Unlike graphene, MXenes are hydrophilic, allowing them to interact readily with water and other polar solvents, making them suitable for various aqueous-based applications.
Mechanical strength: MXenes possess outstanding mechanical properties, with some studies showing that they have higher strength than graphene.
MXene derivatives have been synthesized and unique physical/chemical properties were discovered, showing promise in energy storage and conversions applications. MXene derivatives include 2D transition metal carbides, nitrides, and carbonitrides (MXenes), van der Waals atomic layers and non-van der Waals heterostructures, termination-tailored MXenes, single-atom implanted MXenes, and intercalated MXenes . The relationship between MXene structure, properties, and corresponding applications for derivatives have been studied
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MXene synthesis typically involves two primary steps: selective etching of the parent MAX phase and delamination to obtain single or few-layered MXene sheets.
Selective etching: The first step involves selective etching of the parent MAX phase to remove the A-layer atoms (usually aluminum, silicon, or germanium). Common etching techniques include:
a. Wet chemical etching: Using a mixture of hydrofluoric acid (HF) or a fluoride salt (e.g., LiF, NaF, or NH4F) and a strong acid (e.g., HCl) to selectively etch the A-layer atoms.
b. Electrochemical etching: Applying a potential difference between the MAX phase and a counter electrode in an electrolyte solution to etch the A-layer atoms.
Delamination: Following selective etching, the resulting multilayered MXene sheets must be delaminated to achieve single or few-layered MXene sheets. Delamination methods include:
a. Sonication: The etched material is sonicated in a polar solvent (e.g., water, alcohol, or dimethyl sulfoxide) to separate the layers.
b. Intercalation: The etched material is intercalated with various molecules or ions, which expand the interlayer spacing, followed by sonication or mild mechanical agitation to exfoliate the layers.
Alternative synthesis routes, such as chemical vapor deposition (CVD) and molecular beam epitaxy (MBE), are also being explored for the scalable production of MXenes.
MXene Fundamentals and Applications
MXene’s fundamentals and applications take advantage of their unique properties and versatile surface chemistry make it an attractive material for numerous applications, including but not limited to:
Energy storage: MXenes have shown great potential for energy storage applications, including supercapacitors, lithium-ion batteries, and sodium-ion batteries. Their high electrical conductivity, hydrophilicity, and tunable surface chemistry enable high capacitance and rate performance.
Sensors: MXenes have been utilized in various sensing applications, including strain, pressure, gas, and biosensors. The high sensitivity and quick response times make MXenes ideal candidates for wearable sensors, environmental monitoring, and medical diagnostics.
Electromagnetic interference (EMI) shielding: Due to their high electrical conductivity and good mechanical properties, MXenes have been employed in EMI shielding applications, providing lightweight and efficient shielding materials for the electronics industry.
Water treatment and environmental applications: MXenes have demonstrated their ability to adsorb and remove heavy metal ions, organic pollutants, and even radioactive materials from water, making them promising candidates for water purification and environmental remediation.
Catalysis: The tunable surface chemistry and high electrical conductivity of MXenes have led to their use as efficient electrocatalysts for various reactions, such as the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and carbon dioxide reduction.
Biomedical applications: MXenes have shown potential in drug delivery, photothermal therapy, and tissue engineering due to their biocompatibility, tunable surface chemistry, and photothermal properties.
One of the most promising applications of MXenes is in the field of energy storage and conversion. MXenes have demonstrated superior performance in various energy storage devices, such as:
Supercapacitors: MXenes have high capacitance and excellent rate performance, making them suitable for use as electrode materials in supercapacitors. Their high electrical conductivity and hydrophilicity also contribute to improved energy storage performance.
Batteries: MXenes have been used as anode materials in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), exhibiting high capacity and good cycling stability. Their unique 2D structure and high electrical conductivity contribute to their exceptional battery performance.
Fuel cells and electrocatalysts: MXenes have demonstrated potential as electrocatalysts for various energy conversion reactions, including ORR, HER, and CO2 reduction. Their tunable surface chemistry and high electrical conductivity facilitate increased reaction kinetics and improved catalytic performance.
The price of MXene materials can vary depending on the type, synthesis method, purity, and production scale. Typically, MXenes are more expensive than other 2D materials like graphene due to their relatively complex synthesis and limited commercial availability. However, as production methods become more scalable and efficient, it is expected that the cost of MXenes will decrease, making them more accessible for various applications.
MXene fabrics are composite materials made by incorporating MXene nanosheets into fibrous substrates, such as textiles, nonwovens, or other flexible materials. These fabrics exhibit unique properties, including high electrical conductivity, excellent mechanical strength, and tunable surface chemistry. They have potential applications in wearable electronics, EMI shielding, flexible energy storage devices, and smart textiles.
MXenes conductivity consists of high in-plane electrical conductivity due to their metallic nature and 2D structure, which enables efficient charge transport. The conductivity of MXenes can be tuned by adjusting their surface functional groups and interlayer spacing. This high electrical conductivity makes MXenes suitable for a wide range of applications, such as energy storage, sensors, and EMI shielding.
MXene is pronounced as “max-enes,” with the “max” sound followed by the “ene” rhyming with “scene.”
MXenes, with their unique combination of properties, have emerged as a promising new class of 2D materials. Their high electrical conductivity, hydrophilicity, and exceptional mechanical strength make them attractive candidates for various applications, including energy storage, sensors, EMI shielding, water treatment, catalysis, and biomedical applications. As researchers continue to explore the synthesis, fundamental properties, and potential applications of MXenes, these materials are expected to play a significant role in shaping the future of advanced materials and technologies.
With ongoing advancements in MXene synthesis methods and a growing understanding of their properties, it is anticipated that the cost of MXene materials will decrease over time, making them more accessible for a wide range of applications. As MXene-based products continue to be developed and commercialized, their impact on industries such as electronics, energy, environmental, and healthcare is expected to be substantial.
Overall, MXenes represent an exciting frontier in the field of 2D materials, offering unique properties and diverse applications that have the potential to revolutionize numerous industries. As the scientific community continues to uncover new possibilities for MXene materials, their role in shaping the future of nanotechnology and advanced materials research will undoubtedly continue to grow.
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