28 h In e na ional Symposium on Analy ical and En i onmen al P oblems
PROCEEDINGS OF THE
28 h In e na ional Symposium
on Analy ical and En i onmen al P oblems
Szeged, Hunga y
No embe 14-15, 2022
28 h In e na ional Symposium on Analy ical and En i onmen al P oblems
2
Uni e si y o Szeged
Edi ed by:
Tünde Alapi
Róbe Be kecz
Is án Ilisz
Publishe :
Uni e si y o Szeged, H-6720 Szeged, Dugonics é 13,
Hunga y
ISBN 978-963-306-904-2
2022.
Szeged, Hunga y
28 h In e na ional Symposium on Analy ical and En i onmen al P oblems
323
THE INFLUENCE OF TIP SONICATION ON STRUCTURAL AND
MORPHOLOGICAL PROPERTIES OF GRAPHENE
Andjela S e ano ić1,2, Dejan Kepić1, Milica Budimi 1, Biljana Todo o ić-Ma ko ić1
1Vinča Ins i u e o Nuclea Sciences - Na ional Ins i u e o he Republic o Se bia, Uni e si y
o Belg ade, P.O.B. 522, 11001 Belg ade, Se bia
2Facul y o Chemis y, Uni e si y o Belg ade, S uden ski g 12-16, 11158 Belg ade, Se bia
e-mail: [email p o ec ed]
Abs ac
Al hough ul asound is equen ly used o dispe se ca bon nanoma e ials in sui able sol en s,
he p opaga ion o high-ampli ude ul asonic ib a ions om he ip sonica o was ound o be
agg essi e and has he po en ial o b eak down g aphene shee s. He e, he e ec s o ip
sonica ion ime on s uc u al and mo phological p ope ies o wo ypes o g aphene (g aphene
oxide and elec ochemically ex olia ed g aphene) was in es iga ed by UV- is spec oscopy and
A omic Fo ce Mic oscopy. I was ound ha he s uc u al composi ion o he g aphene was no
a ec ed by ul asounds emi ed om he ip sonica o e en o he p olonged pe iod o
sonica ion (60 min). Mic oscopy analysis showed an inc eased po ion o smalle g aphene
shee s in he sonica ed samples o bo h ypes o g aphene as a esul o g aphene shee
agmen a ion caused by ip sonica ion.
In oduc ion
G aphene is a ma e ial composed o a single-a om laye o sp2 hyb idized ca bon a oms
a anged in a hexagonal honeycomb s uc u e wi h a ca bon-ca bon bond leng h o 0.142 nm
[1]. G aphene is he i s ue wo-dimensional (2D) ma e ial o become a co ne s one in
ma e ials science esea ch e e since i s disco e y in 2004 [2]. Due o i s excep ional and
dis inc i e quali ies, i is equen ly e e ed o as a wonde ma e ial o he u u e [3]. This
unique s uc u e endows g aphene wi h a ious supe io elec onic, op ical, mechanical,
he mal, and magne ic p ope ies, and i has ascina ing applica ions including senso s,
capaci o s, pho oca alys s, nanoelec onics, and nanocomposi es [1].
Howe e , g aphene's limi ed dispe sibili y in wa e and o he common sol en s p esen s a
signi ican p ocessing di icul y. This issue can be sol ed by g aphene being co alen ly
modi ied by s ong oxidan s o in oduce oxygen unc ional g oups and ob ain g aphene oxide
(GO). In he s uc u e o GO, while he bo de s o he shee s ha e ca boxyl and ca bonyl g oups
coupled o sp2 hyb idized ca bon a oms, he base plane o GO has hyd oxyl and epoxy g oups
connec ed o sp3 hyb idized ca bon a oms [4]. Al hough he inal p oduc , is abundan in
unc ional g oups ha include oxygen, he g aphene sp2 honeycomb s uc u e is se e ely
dis u bed, which has a nega i e impac on he ma e ial's pe o mance [3]. G aphene's oxidized
o m con ains hyd ophilic unc ional g oups ha make i easie o p ocess in solu ions and
enable i s mass p oduc ion a a minimal cos . When g aphene oxide is educed in a subsequen
s age, he s uc u e is only pa ially epai ed and a signi ican numbe o s uc u al laws emain.
Despi e he ad an ages, i is impo an o elimina e he unc ional g oups ha include oxygen
o es o e g aphene's o iginal p ope ies, pa icula ly i s elec ical conduc i i y [2].
The elec ochemical p ocess o ex olia ing g aphene in liquids is ano he po en ial low-cos
mass manu ac u ing s a egy o g aphene. Highly o ien ed py oly ic g aphi e (HOPG) is
syn he ic g aphi e ha is ex emely pu e [5].
The majo i y o hese p ocedu es a e based on a modi ied Humme 's me hod, which includes
oxidizing g aphi e using s ong oxidan s. Depending on he equency and in ensi y, ul asound
28 h In e na ional Symposium on Analy ical and En i onmen al P oblems
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p o ides a s ong app oach o he syn hesis o a ious nanoma e ials. Unde s anding he e ec
o sonica ion on he su ace and s uc u e o nanoshee s is impo an because he su ace and
s uc u e o nanoshee s a e c i ical o hei p ope ies and uses [1]. I g aphene can achie e
uni o m dispe sion, i s ex ao dina y cha ac e is ics and s uc u al dis inc i eness can inc ease
he pe o mance o nanocomposi es. As a esul , ul asonic dispe sion o g aphene ( ip o ba h
sonica o ) o nanocomposi e p ocessing is commonly employed o p oduce uni o m
dispe sion. The ip sonica o is ound o be mo e agg essi e, gene a ing en imes he powe o
a ba h sonica o while p oducing high-quali y g aphene in a ac ion o he ime. The sol en
dispe sion unde ip sonica ion includes b eaking down la ge agglome a es by he p opaga ion
o high ampli ude ul asonic ib a ions a equencies anging om 20 kHz o 1 MHz. Va ious
wo ks ha e chosen a ious sonica ion se ings in ecen yea s ( ime, ampli ude, and equency)
[6].
In his wo k, an in es iga ion o ip sonica ion e ec s on wo ypes o g aphene (GO and
elec ochemically ex olia ed g aphene) was p esen ed. G aphene was subjec ed o sonica ion
o a sho (10 min) and a p olonged (60 min) pe iod o ime. The objec i e was o compa e he
in luence o ip sonica ion ea men s on he GO and elec ochemically ex olia ed g aphene
cha ac e is ics by analyzing hei mo phology and chemical s uc u e h ough complemen a y
echniques.
Expe imen al
GO and elec ochemically ex olia ed g aphene we e p epa ed as desc ibed p e iously [5, 7].
Each g aphene sample was dispe sed in deionized MilliQ wa e using an ul asound ba h o
ob ain a g aphene concen a ion o 1 mg/ml. A e ha , g aphene dispe sions we e subjec ed o
sonica ion using a ip sonica o ope a ed a 300 W and 24 kHz wo king equency (Hielsche
UP400S ul asonic p ocesso s) equipped wi h an S24d7 sono ode ( adia ing su ace o 0.38
cm2). The dispe sions we e sonica ed a wo di e en imes (10 and 60 min) wi h an ampli ude
o 72%. To p e en sample o e hea ing, sonica ion was ca ied ou in an ice ba h.
The UV-Vis abso p ion spec a we e eco ded using LLG-uniSPEC 2 spec opho ome e .
Samples we e eco ded in qua z cu e es a oom empe a u e. A omic Fo ce Mic oscopy
(AFM), Quesan (Agou a Hills, CA, USA), was used o he s udy o su ace mo phologies o
samples. AFM was ope a ing in he apping mode, in he ai , a oom empe a u e. S anda d
silicon ip (NanoAndMo e Gmbh, We zla , Ge many) wi h a cons an o ce o 40 N m-1 was
used. Images we e ob ained a a scan a e o 2 Hz, wi h 512 x 512 pixels scan esolu ion o e
a ious squa e a eas. The a e age size o objec s in AFM images was de e mined by Gwyddion
so wa e.
Resul s and discussion
I was specula ed ha he ip sonica ion ene gy and du a ion migh induce s uc u al changes in
g aphene. To es his s a emen , we subjec ed wo ypes o g aphene o ip sonica ion o sho
(10 min) and p olonged ime (60 min). The empe a u e o he dispe sions was kep cons an
using an ice ba h o elimina e he po en ial e ec o o e hea ing on g aphene.
GO dispe sion in wa e has a da k b own colo , while he dispe sion o elec ochemically
ex olia ed g aphene is black. We did no no ice any colo change bo h o GO and
elec ochemically ex olia ed g aphene e en a e he p olonged sonica ion ime. The
dispe sions o GO and elec ochemically ex olia ed g aphene sonica ed o 10 min possess
long- e m s abili y wi h no isible agglome a ion o sedimen a ion se e al weeks a e he
ea men . Howe e , while GO dispe sion sonica ed o 60 min also shows long- e m s abili y,
elec ochemically ex olia ed g aphene sonica ed o 60 min is no s able and ends o
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325
agglome a e. To in es iga e he s uc u al changes in g aphene induced by ip sonica ion, we
pe o med a UV- is analysis ( igu e 1).
Figu e 1. UV- is spec a o GO (a) elec ochemically ex olia ed g aphene (b) subjec ed o
ip-sonica ion o 10 and 60 min.
The UV- is spec um o GO is cha ac e ized by he peak a 230 nm, caused by he π-π*
ansi ion o a oma ic C=C bonds, and a shoulde a ~300 nm a ibu ed o n-π* ansi ion o
C=O bonds. The peak a 230 nm emains i s posi ion a e he sonica ion, and he shoulde a
~300 nm can be obse ed in all he spec a. Ex olia ed g aphene has only a single b oad peak
a 270 nm ha o igina es om π-π* ansi ion o a oma ic C=C bonds. The peak a 270 nm o
elec ochemically ex olia ed g aphene, along wi h he absence o a 300 nm shoulde peak,
sugges s ha i s g aphene s uc u e is la gely e ained [3]. As o GO, he peak a 270 nm in he
spec a o elec ochemically ex olia ed g aphene doesn’ show any shi . This implies ha he
sonica ion o GO and elec ochemically ex olia ed g aphene o selec ed ime in e als didn’
induce s uc u al changes in hese ma e ials [3].
Mo phology analyses o GO and elec ochemically ex olia ed g aphene sonica ed using he ip
sonica o we e conduc ed by AFM ( igu es 2-5). In he AFM images, p is ine GO is domina ed
by la ge shee s wi h sizes o se e al mic ome e s. I was epo ed p e iously ha
elec ochemically ex olia ed g aphene has a b oad dis ibu ion in he shee size (2-12 µm) [5].
Bo h GO and elec ochemically ex olia ed g aphene we e p esen as ew-laye g aphene (FLG).
I is undeniable ha ip sonica ion e icien ly dispe sed bo h ypes o g aphene in wa e .
Howe e , as e ealed in he AFM esul s, high-in ensi y acous ic ca i a ion caused by ip
sonica ion p oduces se e e agmen a ion, de ec o ma ion, and u he ex olia ion o
g aphene. The agmen a ion ends o inc ease wi h sonica ion ime which was con i med by
he la ge po ion o smalle shee agmen s in he images o GO and elec ochemically
ex olia ed g aphene sonica ed o 60 min.
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Figu e 2. AFM image o GO be o e sonica ion (a) he heigh p o ile o he scanned su ace (b)
and 3D ep esen a ion o he g aphene shee (c).
Figu e 3. AFM images o GO a e 10 min o sonica ion.
Figu e 4. AFM images o GO a e 60 min o sonica ion.
28 h In e na ional Symposium on Analy ical and En i onmen al P oblems
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Figu e 5. AFM image o elec ochemically ex olia ed g aphene a e 10 min (a) and 60 min
(b) o sonica ion.
Conclusion
In his pape , UV- is spec oscopy and A omic Fo ce Mic oscopy we e used o explo e he
e ec s o ip sonica ion du a ion on he s uc u al and mo phological ea u es o wo o ms o
g aphene (g aphene oxide and elec ochemically ex olia ed g aphene). The s uc u al
composi ion o g aphene was disco e ed o be una ec ed by ul asounds gene a ed by he ip
sonica o , e en a e an ex ended du a ion o sonica ion (60 min). As a esul o g aphene shee
agmen a ion p oduced by ip sonica ion, mic oscopy examina ion e ealed an inc eased sha e
o smalle g aphene shee s in he sonica ed samples o bo h o ms o g aphene.
Acknowledgemen s
This p ojec has ecei ed unding om he Eu opean Union's Ho izon Eu ope Coo dina ion and
Suppo Ac ions p og amme unde g an ag eemen No 101079151 - G InShield. The esea ch
was also suppo ed by he Science Fund o he Republic o Se bia, #7741955, A e pho oac i e
nanopa icles sal a ion o global in lec ional ea h? - PHOTOGUN4MICROBES and by he
Minis y o Educa ion, Science and Technological De elopmen o he Republic o Se bia,
g an numbe 451-03-68/2022-14/200017.
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