Celebrated for its lightweight, high electrical conductivity, and robust mechanical and thermal properties, graphene found widespread utility across a variety of diverse applications since its discovery in the mid-2000s. As a nanocomposite, it enhances the performance of materials in high-stress environments. Its impressive electrical conductivity and large surface area make it particularly well-suited for advanced applications in energy storage, electronics and biomedicine.
In energy storage, graphene enhanced batteries and supercapacitors with its expansive surface area, providing longer-lasting power and faster recharge times in seconds. In Lithium-ion batteries, graphene serves as a highly efficient anode material, offering a capacity of approximately 1000 mAh g−1—three times that of traditional graphite electrodes. And thanks to its flexibility, graphene is being used in printed, solid-state supercapacitors for textiles used in the production of wearable electronics.
Besides capacitors, graphene is also an excellent choice for the fabrication of transistors due to its exceptionally high carrier mobility at room temperature. Radio frequency top-gate graphene transistors have exhibited cut-off radio frequencies exceeding 155 GHz with gate lengths reduced to 40 nm. Antenna-coupled field effect transistors utilizing graphene have been shown to detect terahertz radiation, paving the way for their application in sensing proteins, biomolecules, cells, gas and even DNA.
With the world pivoting towards greener technology, solar cells have become increasingly essential for generating electrical power, with an emphasis being placed on efficacy in converting light into electricity. Due to its outstanding optical, mechanical and electrical characteristics, graphene has been integrated into dye-sensitized solar cells as electrodes to enhance their photovoltaic efficiency. Cadmium sulfide-graphene nanocomposites, in particular, demonstrate phenomenal photocatalytic activity. Adding graphene to cadmium sulfide semiconductors boosts photostability, augments the number of reaction sites, and bolsters light absorption to further improve solar cell performance.
Nanoporous graphene membranes offer a highly efficient solution for water desalination and filtration, achieving removal rates between 33% and 100%, depending on pore size and applied pressure. With water flow rates reaching up to 100L/cm2day, graphene membranes surpass the performance of traditional reverse osmosis diffusive membranes by several orders of magnitude. On the desalination side, graphene membranes are able to reject up to 97% of sodium chloride from seawater.
In the field of biomedicine, graphene possesses a wide range of usages. In recent times, non-graphene has shown promise for advanced imaging techniques and photothermal therapy. The sensitivity of graphene-based electrodes can be precisely adjusted through surface chemistry modifications, making graphene an ideal material for biosensing applications, such as detecting organic molecules, microbial cells and various biomolecules. Its incredibly large surface area enables effective biomolecule binding, making nano-graphene a powerful carrier for gene and drug delivery systems.
Graphene’s success in drug delivery stems from its distinctive properties, including excellent conductivity, mechanical stability, and biocompatibility. Combining graphene oxide with polymers like polyethylene glycol, and polyvinyl alcohol has led highly efficient adsorbents for hydrophobic molecules. In drug delivery systems, hydrogels also play a vital role; for example, multi-walled carbon nanotubes are added to hydrogels containing methacrylic acid to enhance their electrical responsiveness.
In vivo imaging and photothermal therapy capitalize on graphene’s photosensitivity. Graphene nanoplatelets, with strong near infrared absorbance, low toxicity and high tumor-targeting capabilities, have become valuable in imaging techniques. Pegylated nano-graphene oxide is commonly used for cellular imaging, functioning as a NIR fluorophore for targeted biological samples. In combination of NGS-PEG and NIR laser treatment, studies have demonstrated graphene’s immense potential in targeted cancer therapies.
Graphene stands out as one of the world’s most enticing practical nanomaterials prized for its exceptional properties, captivating researchers and industrialists alike around the globe, and opening doors to breakthrough applications, both scientific and commercial. R&D institutions worldwide have concentrated their efforts on refining synthesis techniques and exploring application in high-demand electronic devices. With future advancements aimed at ultra-thin flexible displays, transparent smartphone touchscreens, medical biosensors, nanorobots and lightweight aerospace materials, graphene is set to transform industries and usher in a new era of state-of-the-art technologies.