. | . |
Development of a single-process platform for the manufacture of graphene quantum dots by Staff Writers Seoul, South Korea (SPX) Dec 06, 2021
Graphene consists of a planar structure, with carbon atoms connected in a hexagonal shape that resembles a beehive. When graphene is reduced to several nanometers (nm) in size, it becomes a graphene quantum dot that exhibits fluorescent and semiconductor properties. Graphene quantum dots can be used in various applications as a novel material, including display screens, solar cells, secondary batteries, bioimaging, lighting, photocatalysis, and sensors. Interest in graphene quantum dots is growing, because recent research has demonstrated that controlling the proportion of heteroatoms (such as nitrogen, sulfur, and phosphorous) within the carbon structures of certain materials enhances their optical, electrical, and catalytic properties. The Korea Institute of Science and Technology (KIST, President Seok-Jin Yoon) reported that the research team led by Dr. Byung-Joon Moon and Dr. Sukang Bae of the Functional Composite Materials Research Center have developed a technique to precisely control the bonding structure of single heteroatoms in the graphene quantum dot, which is a zero-dimensional carbon nanomaterial, through simple chemical reaction control; and that they identified the relevant reaction mechanisms. With the aim of controlling heteroatom incorporation within the graphene quantum dot, researchers have previously investigated using additives that introduce the heteroatom into the dot after the dot itself has already been synthesized. The dot then had to be purified further, so this method added several steps to the overall fabrication process. Another method that was studied involved the simultaneous use of multiple organic precursors (which are the main ingredients for dot synthesis), along with the additives that contain the heteroatom. However, these methods had significant disadvantages, including reduced crystallinity in the final product and lower overall reaction yield, since several additional purification steps had to be implemented. Furthermore, in order to obtain quantum dots with the chemical compositions desired by manufacturers, various reaction conditions, such as the proportion of additives, would have to be optimized. This would inevitably lead to increases in the overall duration of the process and the manufacturing cost per unit. The conventional fabrication method uses acidic precursors or solutions, and thus requires neutralization and purification steps. Conversely, the newly developed process uses weakly alkaline precursors that are neutralized during synthesis, meaning this process has the advantage that the produced graphene quantum dots require no additional processing before they are ready to use. The research team also used computer modeling based on computational chemistry to discover that the solvent used in the synthesis process of graphene quantum dots affects the oxidation of the organic precursor, fumaronitrile, which also contains the heteroatoms (nitrogen). This implied that the solvent type ultimately determines the chemical composition of the final graphene quantum dot product. Furthermore, the theoretical oxidation energy value of the organic precursor, which was calculated based on the particular solvent used, was experimentally proven to have the ability to predict the approximate chemical composition of the final graphene quantum dot. Dr. Sukang Bae of KIST stated, "We have developed a new platform technology that allows us to synthesize graphene quantum dots by selectively adjusting the chemical composition of heteroatoms with a single synthetic process, without the use of other additives other than organic precursors such as fumaronitrile," and added, "Because we discovered a way to achieve the mass synthesis of graphene quantum dots without additional post-processing or purification processes, we were able to reduce the overall processing time and increase the economic feasibility of the synthetic procedure." Furthermore, this achievement is expected to drive the development of nanocarbon materials, as well as increase economic opportunities for small and medium-sized enterprises, and further the growth of human resources in connection with the expansion of the carbon-materials industry, which is the regional strategic industry of the Jeollabuk-do Province.
Research Report: Structure-controllable growth of nitrogenated graphene quantum dots via solvent catalysis for selective C-N bond activation
Satellites to enable monitoring of CO2 emissions Lund, Sweden (SPX) Dec 02, 2021 Researchers have developed a model that can calculate individual countries' carbon dioxide emissions from fossil fuel burning using observations from space. The new results could be put to use within the Earth observation programme Copernicus, when satellites will be sent into space in the coming years. At the COP26 climate summit, the nations of the world agreed on a new document that for the first time mentions phasing out coal and fossil fuels, and reiterates the Paris Agreement's 1.5-degree ta ... read more
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |