Converting fish scales into high-quality nanomaterials.
(Left) Scheme depicting the synthesis of carbon nano-onions via the microwave pyrolysis of fish scales. The top inset shows the rise in temperature of the fish scales due to microwave absorption over a period of 10 seconds, as well as a proposed formation mechanism for the carbon nano-onions.
(Right) transmission electron microscopy images showing the morphology of the synthesized carbon nano-onions and photographs of CNO dispersion in ethanol, an emissive flexible film, and an LED containing CNO.
Image credit: Takashi Shirai from NITech, Japan.
Thanks to their low toxicity, chemical stability, and remarkable electrical and optical properties, carbon-based nanomaterials are finding more and more applications across electronics, energy conversion and storage, catalysis, and biomedicine. Carbon nano-onions (CNOs) are certainly no exception. First reported in 1980, CNOs are nanostructures composed of concentric shells of fullerenes, resembling cages within cages. They offer multiple attractive qualities such as a high surface area and large electrical and thermal conductivities.
Unfortunately, the conventional methods for producing CNOs have some serious drawbacks. Some require harsh synthesis conditions, such as high temperatures or vacuum, while others demand a lot of time and energy. Some techniques can circumvent these limitations, but instead call for complex catalysts, expensive carbon sources, or dangerous acidic or basic conditions. This greatly limits the potential of CNOs.
Fortunately, not all hope is lost. In a recent study published in Green Chemistry (available online on April 25, 2022, and published in issue 10 on May 21, 2022), a team of scientists from Nagoya Institute of Technology in Japan found a simple and convenient way to turn fish waste into extremely high-quality CNOs. The team, which included Assistant Professor Yunzi Xin, Master’s student Kai Odachi, and Associate Professor Takashi Shirai, developed a synthesis route in which fish scales extracted from fish waste after cleaning are converted into CNOs in mere seconds through microwave pyrolysis.
But how can fish scales be converted into CNOs so easily? While the exact reason is not altogether clear, the team believes that it has to do with the collagen contained in fish scales, which can absorb enough microwave radiation to produce a fast rise in temperature. This leads to thermal decomposition or “pyrolysis,” which produces certain gases that support the assembly of CNOs. What is remarkable about this approach is that it needs no complex catalysts, nor harsh conditions, nor prolonged wait times; the fish scales can be converted into CNOs in less than 10 seconds!
Moreover, this synthesis process yields CNOs with very high crystallinity. This is remarkably difficult to achieve in processes that use biomass waste as a starting material. Additionally, during synthesis, the surface of the CNOs is selectively and thoroughly functionalized with (?COOH) and (?OH) groups. This is in stark contrast to the surface of CNOs prepared with conventional methods, which is typically bare and has to be functionalized through additional steps.
This “automatic” functionalization has important implications for applications of CNOs. When the CNO surface is not functionalized, the nanostructures tend to stick together owing to an attractive interaction known as pi?pi stacking. This makes it difficult to disperse them in solvents, which is necessary in any application requiring solution-based processes. However, since the proposed synthesis process produces functionalized CNOs, it allows for an excellent dispersibility in various solvents.
Yet another advantage associated with functionalization and the high crystallinity, is that of exceptional optical properties. Dr. Shirai explains: “The CNOs exhibit ultra-bright visible-light emission with an efficiency (or quantum yield) of 40%. This value, which has never been achieved before, is about 10 times higher than that of previously reported CNOs synthesized via conventional methods.”
To showcase some of the many practical applications of their CNOs, the team demonstrated their use in LEDs and blue-light-emitting thin films. The CNOs produced a highly stable emission, both inside solid devices and when dispersed in various solvents, including water, ethanol, and isopropanol. “The stable optical properties could enable us to fabricate large-area emissive flexible films and LED devices,” speculates Dr. Shirai. “These findings will open up new avenues for the development of next-generation displays and solid-state lighting.”
Furthermore, the proposed synthesis technique is environmentally friendly and provides a straightforward way to convert fish waste into infinitely more useful materials. The team believes their work would contribute to the fulfillment of several of UN’s Sustainable Development Goals. Additionally, if CNOs make their way into next-generation LED lighting and QLED displays, they could greatly help reduce their manufacturing costs.
Let us hope the efforts of these scientists tip the scales in favor of CNOs for more practical applications!
Original Article: Turning Fish Waste into Quality Carbon-based Nanomaterial
More from: Nagoya Institute of Technology
The Latest Updates from Bing News
Go deeper with Bing News on:
- A Kenyan start-up turns plastic waste into solar-powered freezers
A Kenyan company is proving the saying: "one person's waste is another person's treasure," still rings true. On a February morning, a group of women on a Mombasa beach pick up plastic waste that will ...
- Waste company ordered to pay £68,500 after cyanide leak kills hundreds of fish
A waste transport company has been ordered to pay £68,500 after hundreds of litres of a liquid containing diluted cyanide leaked from a lorry.
- Kitchen scrap kimchi and other low-waste recipes from the James Beard Foundation
All of the recipes utilize multiple components of an ingredient to reduce waste. Using up every part of an ingredient ... peeled and chopped 1/4 cup fish sauce 2 tablespoons sugar Directions: Toss the ...
- Philly might need to raise water bills to get your pee out of the Delaware River, protect fish
The EPA says Philly and other cities have to do more to remove ammonia, a byproduct of human waste, from the wastewater that goes into the Delaware River.
- Some anglers worry about state proposal to close Salisbury fish hatchery
Photo courtesy of the Vermont Fish & Wildlife Department To the dismay of some anglers ... Herrick said the hatchery may not be eligible for a water quality permit in 2027 because of waste discharged ...
Go deeper with Bing News on:
- Onions in your socks? Unpeeling the layers of this flu myth with expert insights
In the world of unconventional remedies, the trend of placing onions in socks to combat cold and flu symptoms has gained attention. While home remedies have been a part of traditional medicine ...
- Grow it Green: Growing onions
AND STEPH, WE’RE TALKING ABOUT TODAY GROWING YOUR OWN ONIONS. AND MY QUESTION FOR YOU IS WHY. YOU KNOW, I CAN GO INTO THE GROCERY STORE AND I SEE THE RACKS AND RACKS OF ONIONS THERE RIGHT.
- Smuggled onions booming online
MANILA, Philippines — Smuggled and imported onions being sold online have contributed to the slump in the farmgate price of local bulbs, according to a farmers’ group. In an interview with The ...
- The No. 1 Trick To Stop Crying When Cutting Onions, According to a Chef
If only we knew how to stop crying when chopping onions to spare us—and the millions of other onion victims—some of the pain. Thankfully, Eric Rowse, a lead chef-instructor of culinary arts at ...
- OECD Tour de Table Includes Information on U.S. Developments on the Safety of Manufactured Nanomaterials
Since January 2005, EPA has received and reviewed more than 275 new chemical notices for nanoscale materials under TSCA, including fullerenes and carbon nano-onions, quantum dots, semiconducting ...