January 11, 2024 - As countries around the world pledge to transition to other means of energy production due to their contribution to climate change, researchers and scientists are looking at other ways to utilize coal. 

To reevaluate the fossil fuel's economic role, the Taiwan Semiconductor Manufacturing Company, the National Energy Technology Laboratory, the University of Illinois Urbana-Champaign, and Oak Ridge National Laboratory came together for a joint research effort and demonstrate the critical role coal can play in next-generation electronic devices.

In recent years, a lot of research has been happening in the field of 2D materials due to their electrical, optical, and mechanical properties. The synthesis of a range of atomically thin 2D materials opens a new platform for layer-by-layer materials that enable the exploration of unknown properties, promising a range of new technologies. 

2D layered semiconductors possess features like high mobility, low-power switching, relatively large bandgap, and the availability of large-area growth methods, which makes them a promising candidate for the next generation of electronics. Now, coal is being experimented with for usage in such electronics. 

“Coal is usually thought of as something bulky and dirty, but the processing techniques we've developed can transform it into high-purity materials just a couple of atoms thick.” 

– said Qing Cao, a U. of I. materials science & engineering professor who co-led the effort. 

He also noted:

“Their unique atomic structures and properties are ideal for making some of the smallest possible electronics with performance superior to the state of the art.”

Under this collaboration, the researchers developed a process that converted coal char into extremely small carbon disks, which are called “carbon dots.” 

As shown by the research group, these nanoscale carbon disks can be connected to create atomically thin membranes. These membranes can be used for applications in technologies like two-dimensional (2D) transistors and memristors. According to researchers, these technologies will be critical in constructing more efficient electronics. 

While carbon-based materials, whether it's traditional industrial carbon like carbon black or new industrial carbon like graphite and carbon fibers, play significant roles in the development of material science, macroscopic carbon material can't really be used as an effective fluorescent material due to a lack of the appropriate band gap. This is where carbon dots (CDs) have emerged as a promising solution.

Carbon dots or CDs are a new type of carbon-based nanomaterial that have garnered much attention and research interest due to their diverse physicochemical properties. Carbon dots are meticulously formulated and usually smaller than 10 nm in size. This carbon-based nanomaterial has features like small size, ecofriendliness, low cost, low toxicity, high stability, good biocompatibility, electron mobility, high quantum yield, abundant functional groups, and unique optical properties, including strong absorption, photoluminescence, and phosphorescence.

All of these qualities make this new material in the carbon family so popular and have many applications. This includes:

• Sensors
• Information encryption
• Photocatalysis
• Light-emitting diodes
• Chemical sensing
• Solar cells
• Supercapacitors
• Rechargeable batteries
• Bioimaging
• Phototherapy
• Gene delivery
• Drudge delivery
• Explosive detection
• Nanomedicine
• Food safety
• Anticounterfeiting

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