Possible changes in graphene synthesis protocols

A team of researchers at IIT-Gandhinagar in India has discovered an unexpected phenomenon that could have significant implications on the existing protocols followed to synthesize graphene and other two-dimensional (2D) nanomaterials.

An unexpected observation using the current method to synthesize graphene

A popular method to synthesize graphene is liquid-phase exfoliation, in which the graphite powder is mixed in a suitable liquid medium and exposed to bursts of high-intensity sound energy (ultrasonication). This ultrasonic energy delaminates the layered parent crystals into daughter nanosheets that suspend and swim in the organic solvents to form a stable dispersion of 2D nanomaterials.

In this method, it was presumed that the ultrasonic energy bursts would not affect the organic solvent. However, the research team stumbled upon a surprise. They were extending this method to synthesize dispersions of borophene, a 2D material that is like graphene but made from boron. While conducting the control experiments, doctoral student Saroj Kumar Das made an unexpected observation that the organic solvent itself was transforming into quantum dots − extremely tiny fluorescent nanostructures just 2nm in diameter.

The discovery

Das reportedly made this observation when he was shining the dispersion with a laser and it exhibited beautiful fluorescent colours, a behaviour that is characteristic to quantum dots. Such a concurrent formation of quantum dots, along with the formation of nanosheets, has not been seen before.

Initially, the team assumed that these quantum dots could have come from possible contamination. However, after conducting several experiments in different setups and verifying the results, the team was able to validate that the organic solvent used during the process itself is transforming into carbon quantum dots.

This was a surprise finding because scientists till now believed that the liquid medium or organic solvent remains stable during exposure to sound waves and nothing happens to it. That is the main reason these are used as a dispersing medium for such experiments. No one has ever suspected that the molecules of organic solvent can transform into carbon quantum dots by the sound energy. This new physical insight would form an important addition to the protocols followed to synthesize nanosheets,” IIT’s Dr. Kabeer Jasuja said.

Application for other 2D materials

To demonstrate the relevance of these results, the research team also revisited protocols that utilise ultrasonication to synthesize other 2D materials. They found that in these protocols, one ends up getting a mixture of carbon quantum dots along with the 2D nanosheets that are originally intended. The findings imply that before drawing inferences about nanosheets formed by such methods, one needs to acknowledge the presence of these quantum dots.

Source: Graphene-info


Leggi anche

I compositi realizzati con materiali inorganici autoassemblanti sono apprezzati per la loro forza unica e per le proprietà termiche, ottiche e magnetiche. Tuttavia, l’autoassemblaggio può essere difficile da controllare e le strutture formate fortemente disordinate, con conseguenti difetti durante la produzione su larga scala. Un gruppo di ricercatori dell’Università dell’Illinois e dell’Università del Michigan ha sviluppato una tecnica di modellazione che garantisce maggiore ordine e dà luogo a nuove strutture 3-D in una classe speciale di materiali, chiamati eutettici, per formare nuovi materiali ad alte prestazioni…

Leggi tutto…

Il progetto MAT4RAIL ha sviluppato nuove formulazioni di resine ibride che consentiranno di sostituire le componenti metalliche dell’infrastruttura e dei vagoni ferroviari con materiali compositi più leggeri. Le parti interne intelligenti delle vetture sono state inoltre progettate per aumentare la capienza e offrire un maggiore comfort per i passeggeri…

Leggi tutto…

Un gruppo di ricercatori del Georgia Institute of Technology e The Ohio State University ha sviluppato un nuovo materiale polimerico, che cambia forma a contatto con i campi magnetici. Questo nuovo materiale potrebbe trovare applicazione in molti settori diversi…

Leggi tutto…

Prorogato di altri 12 mesi il periodo transitorio che ammette l’impiego di materiali compositi FRCM per il consolidamento di costruzioni esistenti, al termine del quale potranno essere impiegati solo materiali qualificati in possesso di Certificato di Valutazione Tecnica rilasciato dal Servizio tecnico centrale del Consiglio superiore dei Lavori pubblici…

Leggi tutto…

Un team di ricercatori del KTH Royal Institute of Technology ha sviluppato un nuovo materiale composito costituito dalla combinazione di nano fibrille di cellulosa di legno (CNF) e MXene, un materiale conduttore bidimensionale…

Leggi tutto…