Sus ainable gamma i adia ion s a egy o GO and GO modi ica ion:
Impac on elec omagne ic in e e ence shielding e iciency
Jo ana P ekod a ac Filipo ic
a,*
, Mila Milenko ic
a
, Duska Kleu
a
, Kamel Haddadi
b
,
Muhammad Yasi
c
, Wa da Saeed
c
, Danica Bajuk Bogdano ic
d
, S e lana Jo ano ic
a
a
Vinˇ
ca 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, Belg ade, Se bia
b
Uni e si y o Lille, CNRS, Cen ale Lille, Uni e si y Poly echnique Hau s-de-F ance, UMR 8520-IEMN-Ins i u d’Elec onique de Mic o´
elec onique e de
Nano echnologie–Lille, F ance
c
Depa men o Compu e Science, Di ision o Mic o obo ics and Con ol Enginee ing, Uni e si y o Oldenbu g, Oldenbu g, Ge many
d
Facul y o Physical Chemis y, Uni e si y o Belg ade, Belg ade, Se bia
ARTICLE INFO
Keywo ds:
G aphene oxide
Reduced g aphene oxide
Gamma i adia ion
Elec omagne ic in e e ence
Shielding
ABSTRACT
Elec omagne ic in e e ence (EMI) has eme ged as a signi ican issue in con empo a y elec onic sys ems,
pa icula ly wi hin ae ospace, de ense, and communica ion echnology. G aphene-de i ed ma e ials, including
g aphene oxide (GO) and educed g aphene oxide ( GO), p esen ema kable po en ial o ligh weigh , lexible,
and EMI shielding solu ions owing o hei adjus able elec ical conduc i i y and s uc u al in eg i y. This s udy
in oduces an eco- iendly me hod o adjus ing he EMI shielding e ec i eness (EMI SE) o ee-s anding ilms
made om GO and GO by con olled gamma i adia ion a low (50 kGy) and high (300 kGy) doses, conduc ed in
wo ypes o media: ai and isop opyl alcohol (IPA). The s uc u al al e a ions gene a ed by i adia ion we e
cha ac e ized by Raman and In a ed spec oscopies, X- ay di ac ion (XRD), scanning elec on mic oscopy
(SEM), and con ac angle measu emen s, indica ing changes in de ec densi y, su ace oughness, and hyd o-
philici y. Resul s indica e ha gamma i adia ion can p ecisely adjus he oxida ion/ educ ion equilib ium,
hence boos ing conduc i i y in GO and imp o ing in e acial pola iza ion in GO. Rema kably, GO ilms
exposed o ai demons a ed excep ional EMI SE alues abo e 20 dB in he X-band (8–12 GHz), signi ying hei
sui abili y o ad anced shielding applica ions. This esea ch illus a es he e ec i eness o gamma i adia ion as
an en i onmen ally iendly, scalable me hod o modi ying he cha ac e is ics o g aphene-based ma e ials,
acili a ing hei inco po a ion in o ad anced ae onau ical and elec onic equipmen .
1. In oduc ion
The eme gence o new en i onmen al pollu ion issues, including
elec omagne ic pollu ion and elec omagne ic in e e ence (EMI) om
elec ical and elec onic de ices, has signi ican ly escala ed due o he
swi ad ancemen o in o ma ion echnology. Elec onics and hei
componen s, cha ac e ized by inc eased powe , educed size, and
enhanced ope a ional speed, c ea e undesi able elec omagne ic wa es
ha can cause mal unc ion and de e io a ion o de ices, as well as pose
isks o human heal h and he en i onmen [40,49].
G aphene oxide (GO) and educed g aphene oxide ( GO) ha e
ecen ly eme ged as highly p omising ca bon-based nanoma e ials
because o hei ema kable s uc u al, he mal, and elec ical
p ope ies [29,43,48]. GO, a highly oxidized a ian o g aphene, is
abundan in oxygen-con aining unc ional g oups ha con e hyd o-
philici y and acili a e e o less dispe sion in wa e and o he sol en s.
Upon educ ion, GO is la gely ans o med in o GO, es o ing sp² hy-
b idized ca bon ne wo k, hus imp o ing i s elec ical conduc i i y
while p ese ing some unc ional g oups ha enhance s uc u al plas-
ici y. The dis inc i e p ope ies o GO and GO ende hem appealing
o nume ous ad anced echnical applica ions, especially in elec onics,
sensing, ene gy s o age, and EMI shielding [18,27,36,45,54].
The capaci y o p oduce ee-s anding ilms o GO and GO is a i al
ad ancemen o hei p ac ical inco po a ion in o gadge s. Such ilms
p o ide lexibili y, scalabili y, and mechanical du abili y wi hou
equi ing suppo ing subs a es. Con en ional me hods, such as
* Co esponding au ho a : Vinˇ
ca 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, Mike Pe o ica Alasa 12-14,
Vinca, Belg ade 11351, Se bia.
E-mail add ess: [email p o ec ed] (J.P. Filipo ic).
Con en s lis s a ailable a ScienceDi ec
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h ps://doi.o g/10.1016/j.ceja.2025.100873
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
A ailable online 16 Sep embe 2025
2666-8211/© 2025 The Au ho s. Published by Else ie B.V. This is an open access a icle unde he CC BY license ( h p://c ea i ecommons.o g/licenses/by/4.0/ ).
Langmui -Blodge [55], we spinning [28], sp ay coa ing [37] e c.,
equen ly ha e con amina ion issues o es ic ed scalabili y [11]. The
s ong Van de Waals in e ac ions be ween GO and a ious subs a es
esul in signi ican adhesion, making he sepa a ion o GO ilms om
hese subs a es pa icula ly challenging. As a esul , he e is an
inc easing demand o cos -e ec i e subs a es ha allow acile emo al
wi hou lea ing behind esidues o causing s uc u al damage o he GO
ilms. Con e sely, memb ane-assis ed cas ing p ocesses o e a hygienic,
economical, and consis en app oach o gene a ing homogenous, lex-
ible, and subs a e- ee ilms [33]. These ilms can subsequen ly unde go
pos - ea men , such as chemical o adia ion-induced educ ion, o
modi y hei cha ac e is ics o pa icula pu poses.
Gamma i adia ion, commonly employed in he s e iliza ion o
medical o scien i ic equipmen , has been u ilized o al e he physico-
chemical p ope ies o ca bon-based ma e ials a he nanoscale [2].
Gamma i adia ion is a high-ene gy p ocessing me hod ha employs
pho ons, ypically om Co
60
, which pene a e deeply in o ma e ials and
ans e ene gy h ough ioniza ion and exci a ion. This p ocess gene -
a es seconda y elec ons and eac i e species ha can clea e chemical
bonds, o m adicals, and ini ia e oxida ion o educ ion depending on
he su ounding a mosphe e and medium. In oxygen- ich en i onmen s,
i adia ion p omo es oxida i e pa hways and he o ma ion o oxygen-
a ed g oups, whe eas unde ine a mosphe es o in aqueous suspensions
wi h adical sca enge s, educ i e chemis y domina es, emo ing ox-
ygen unc ionali ies and es o ing conjuga ed s uc u es [25]. The e -
ec s o gamma i adia ion a e signi ican ly in luenced by he i adia ion
condi ions, such as o al dose, dose a e, a mosphe e, empe a u e, he
na u e o ma e ials, and he i adia ion medium which collec i ely
de e mine whe he c osslinking, chain scission, oxida ion, o educ ion
will p e ail. A ple ho a o ins ances demons a ing a ious (o e en
con adic ing) ou comes ollowing i adia ion unde di e se si ua ions is
a ailable in he li e a u e [51]. Conce ning g aphene, gamma i adia-
ion in a ious liquid media, has been e ec i ely employed o he
oxida ion/ educ ion o GO and GO [7,13,52]. In he con ex o g a-
phene oxide, gamma i adia ion has been widely used as a g een and
scalable me hod o une i s chemis y: in ai o oxygena ed sys ems
i adia ion can inc ease oxida ion o in oduce de ec s, while in ine
en i onmen s o aqueous suspensions con aining alcohols ha sca enge
oxidizing adicals, i e icien ly educes GO by emo ing epoxide, hy-
d oxyl, and ca boxyl g oups and pa ially es o ing sp² domains. P ope
dose con ol is c i ical, as mode a e i adia ion enhances he C/O a io
and conduc i i y, bu excessi e doses can damage he ca bon la ice and
gene a e s uc u al de ec s. Thus, gamma i adia ion p o ides a
con ollable, chemical- ee ou e o he oxida ion o educ ion o g a-
phene oxide, enabling he p oduc ion o educed g aphene oxide wi h
ailo ed p ope ies o elec onic, ca aly ic, and en i onmen al appli-
ca ions [56].
One o he po en ial applica ions o ca bon-based nanoma e ials is
EMI shielding. Owing o hei supe io elec ical conduc i i y and
laye ed a chi ec u e, ca bon-based nanoma e ials demons a e excep-
ional a enua ion o elec omagne ic wa es o e a b oad equency
spec um [9,46]. EMI shielding is essen ial in con empo a y elec onics
and communica ion echnologies, pa icula ly wi hin he ae ospace in-
dus y, whe e weigh , du abili y, and pe o mance unde ha sh condi-
ions a e c i ical conside a ions. Mo eo e , he inhe en esis ance o GO
and GO o ionizing adia ion—pa icula ly when subjec ed o p ocesses
like gamma i adia ion—posi ions hem as o midable p ospec s o
applica ions in ae onau ical and as onomical echnology, whe e ma-
e ials mus endu e se e e adia ion condi ions.
This pape in oduces a sys ema ic me hod o p oducing highly
lexible, con amina ion- ee, ee-s anding ilms o GO and GO u ilizing
memb ane il e s as de achable subs a es. The ilms we e u he sub-
jec ed o a ious gamma i adia ion doses in wo di e en en i onmen s
- ai and isop opyl alcohol (IPA), o induce s uc u al modi ica ions and
enhance hei elec omagne ic in e e ence shielding e ec i eness (EMI
SE). The GO ilms exhibi ed signi ican ly enhanced EMI SE alues
exceeding 20 dB, in con as o he GO ilms, which demons a ed much
lowe e ec i eness ( anging om 0.31 dB o 0.52 dB). The indings
sugges ha gamma i adia ion can in oduce su icien s uc u al
modi ica ion o p omo e EMI SE, bu je again i does no subs an ially
al e he s uc u al in eg i y o he ma e ials, highligh ing hei obus -
ness and sui abili y o demanding applica ions such as ae ospace and
as onomical echnologies. The e o e, he aim o he wo k is o de elop a
sys ema ic app oach o ab ica ing lexible, con amina ion- ee, ee-
s anding GO and GO ilms using memb ane il e s as de achable sub-
s a es, and o in es iga e he in luence o gamma i adia ion unde
di e en en i onmen s on hei s uc u al p ope ies and elec omag-
ne ic in e e ence shielding e ec i eness, wi h he goal o p oducing
obus , high-pe o mance ma e ials sui able o ad anced applica ions
such as ae ospace and as onomical echnologies.
2. Ma e ials and me hods
2.1. P epa a ion o ee-s anding ilms o GO and GO
GO was syn hesized by chemical oxida ion o g aphi e using a
modi ied Humme s’ me hod [6]. Ini ially, 1 g o g aphi e powde
(TIMREX® Z-346 KS6, Bodio, Swi ze land) was added o 23.3 mL o
concen a ed sul u ic acid (Ca l Ro h, Ka ls uhe, Ge many) a 4 ◦C.
While s i ing, 3 g o po assium pe mangana e (Me ck, Da ms ad ,
Ge many) was slowly in oduced in small amoun s. The mix u e was
kep unde s i ing o 30 min o ho ough mixing and eac ion ini ia-
ion. Subsequen ly, i was gen ly hea ed o 40 ◦C. Following he addi ion
o 50 mL o demine alized wa e , he mix u e was kep a ha empe -
a u e o 30 min. Following he addi ion o 50 mL demine alized wa e ,
he mix u e was s i ed a 95 ◦C o 15 min. Subsequen ly, 166.7 mL o
wa e was added, ollowed by he slow addi ion o 5 mL o 30 %
hyd ogen pe oxide, esul ing in a colo change om da k b own o
yellow. The mix u e was main ained a 95 ◦C o an addi ional 15 min
and hen cooled o oom empe a u e. The suspension was il e ed,
washed wi h 83.3 mL o dilu ed HCl (1:10), dispe sed in 200 mL o wa e
and pu i ied by dialysis (MWCO 8000–14,000 g mol
-1
) o se en days.
Finally, he dispe sion was sonica ed and cen i uged a 3000 pm in
o de o isola e GO. The esul ing GO dispe sion was dilu ed wi h
demine alized wa e o 1 mg mL
-1
and used o ilm ab ica ion.
GO hin laye s we e o med by sonica ing 22.5 mL o an aqueous GO
suspension o 30 min, ollowed by acuum-assis ed il a ion using a
0.22
μ
m po e-size hyd ophilic polyca bona e memb ane (Isopo e™,
GTTP02500, Me ck). Uni o m p essu e gene a ed by he acuum
allowed o e en GO laye o ma ion. A e il a ion and d ying, he
ilms we e peeled om he memb ane. The as-p epa ed hin ilms we e
subsequen ly subjec ed o educ ion o ob ain GO hin ilms. The
schema ic ep esen a ion o he ee-s anding ilms o GO and GO
p epa a ion is p esen ed in Scheme 1.
To achie e chemical educ ion, he GO ee-s anding ilms we e
ea ed in a 15.14 mM l-asco bic acid aqueous medium wi h pH
adjus men using 100
μ
L o concen a ed HCl (5 M). The samples we e
hen hea ed a 85 ◦C o 8 h, hen gen ly washed wi h deionized wa e
and d ied in he ai .
2.2. Gamma i adia ion o ee-s anding ilms o GO and GO
F ee-s anding ilms o GO and GO we e cu in o size 11 ×22 mm,
and submi ed o he gamma i adia ion (Co
60
sou ce) a di e en dos-
ages (50, 100, 200, and 300 kGy) in ai and IPA media o p omo e
oxida ion and educ ion o he su ace. Due o he ex en numbe o
samples, he sample names and he co esponding condi ions o hei
p epa a ion a e shown in Table 1.
2.3. EMI SE measu emen s
Elec omagne ic in e e ence shielding e ec i eness (EMI SE) o
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
2
ee-s anding GO samples was ob ained using a ec o ne wo k analyze
(VNA, a Rohde & Schwa z ZVA 24 Vec o Ne wo k Analyze , Munich,
Ge many). Namely, VNA was used o measu e he S-pa ame e s in he
8–12 GHz equency ange. F ee-s anding samples o gamma-i adia ed
GO we e cu in o a ec angula shape, 15 mm x 25 mm, o co e he WR-
90 wa eguide adap e s’ inne space.
RF coaxial cables we e used o connec WR-90 wa eguide adap e s
wi h po s 1 and 2 o he VNA. The gamma i adia ed GO ilms we e
posi ioned be ween he 2 wa eguide adap e s, and he alues o S
sca e ing pa ame e s we e collec ed, as p e iously epo ed [26].
The o al shielding e ec i eness was es ima ed using Eqs. (1)–(3) [3,
32]:
SE =LD+LM(1)
whe e SE is he sum o dissipa ion loss L
D
, and misma ch loss L
M
.
The L
M
is calcula ed using ela ion (2):
LM= − 10log10(1− |S11|2)(2)
To ob ain he alue o L
D
, he e lec ion sca e ing pa ame e , S
11
,
and ansmission sca e ing pa ame e , S
21
, we e used (3):
LD= − 10log10((|S21|2)/(1− |S11|2)(3)
Pa ame e s S
11
and S
21
we e collec ed by using a VNA.
2.4. Ma e ials cha ac e iza ion
We employed he INCAx-ac LN2- ee analy ical silicon d i de ec o
o SEM-EDS, ea u ing Pen aFET® P ecision and he Az ec 4.3 so wa e
package (Ox o d Ins umen s, Ox o dshi e, UK), linked o a TESCAN
Mi a3 XMU ope a ing a 20 kV wi h a seconda y elec on de ec o . BP
and BG powde s we e applied o he conduc i e double-sided adhesi e.
Raman spec a o samples we e ob ained by a DXR Raman mic oscope
(The mo Scien i ic) using a 532 nm lase as an exci a ion sou ce. The
lase powe was kep a 2 mW o a oid hea ing o he sample wi h a
pixel- o-pixel spec al esolu ion o 1 cm
-1
. Fou ie - ans o m in a ed
(FTIR) spec a we e eco ded using a Nicole iS20 FTIR spec ome e
(The mo Scien i ic) equipped wi h an ATR accesso y ea u ing a dia-
mond c ys al. Measu emen s we e pe o med in he ange o 4000–525
cm⁻¹, using 16 scans pe sample and a spec al esolu ion o 4 cm⁻¹. P io
o each measu emen , he ATR c ys al was ho oughly cleaned o a oid
con amina ion. The samples we e analyzed di ec ly, wi hou any addi-
ional chemical p epa a ion, by p essing hem on o he c ys al su ace.
3. Resul s and discussion
3.1. SEM/EDS in es iga ion
The su ace mo phology o p is ine and gamma-i adia ed GO sam-
ples was in es iga ed using SEM analysis. The op iew image (Fig. 1a)
o GOp shows a uni o m dis ibu ion o he GO shee s on a la ge scale
wi h ough and wa y su ace, while unde gamma ea men (GO_ai _50
kGy) in ai (Fig. 1b) he su ace becomes mo e co uga ed.
Fu he inc ease in gamma dosage (Fig. 1c, d) caused he o ma ion
o loose GO shee s on op o he ee-s anding ilms su ace p obably as a
esul o he oxida ion p ocess, while i adia ion a 300 kGy (Fig. 1e)
in luenced he mo phology by a anging he su ace in a mo e o ganized
s uc u e. The educ ion in IPA (Fig. 1h-j) a ec ed he GO su ace by
p o iding mo e la ened mo phology, when compa ed o he GOp, wi h
agglome a e o ma ion as a esul o he su ace dis u bance by educ-
ion. Once again, in a sample GO_IPA_300 kGy (Fig. 1j), a mo e a anged
su ace was obse ed. In he GO samples, a mo e w inkled o wa y
mo phology (Fig. 2) was de ec ed when compa ed o he GO samples
which can be a esul o se e al domina ing ac o s. By emo ing oxygen
unc ional g oups, he es ablishmen o
π
-
π
in e ac ion be ween g a-
phene shee s is occu s [17,38].
The op- iew image (Fig. 2a) o GOp exhibi s a homogeneous dis-
ibu ion o GO shee s on a wide scale, cha ac e ized by a ough and
undula ing su ace. In con as , ollowing gamma ea men in ai
(Fig. 2b-e), he su ace becomes inc easingly co uga ed wi h agglom-
e a e o ma ion as a esul o he su ace dis u bance. This is p obably
due o he o ma ion o loose GO shee s on op o he ee-s anding
ilm’s su ace as a esul o he oxida ion p ocess [5]. Wi h an inc ease
in he gamma i adia ion dosage om 50 o 300 kGy, a mo e dis u bed
su ace was no iced. In he educ ion medium (Fig. 2g-j), imp o emen
o he su ace oughness and wa iness was obse ed.
The inc eased wa iness in GO ee-s anding ilms, when compa ed
o GO, mos ly esul s om s uc u al elaxa ion, de ec educ ion, and
he loss o plana alignmen , which is o en p ese ed in he mo e
Scheme 1. Th ee s eps o p oduc ion o ee-s anding ilms o GO and GO.
Table 1
Lis o samples and induced gamma dosages.
Sou ce Medium Gamma i adia ion dosage (kGy) Sample name
GO - - GOp
GO ai 50 GO_ai _50kGy
GO ai 100 GO_ai _100kGy
GO ai 200 GO_ai _200kGy
GO ai 300 GO_ai _300kGy
GO IPA 50 GO_IPA_50kGy
GO IPA 100 GO_IPA_100kGy
GO IPA 200 GO_IPA_200kGy
GO IPA 300 GO_IPA_300kGy
GO - - GOp
GO ai 50 GO_ai _50kGy
GO ai 100 GO_ai _100kGy
GO ai 200 GO_ai _200kGy
GO ai 300 GO_ai _300kGy
GO IPA 50 GO_IPA_50kGy
GO IPA 100 GO_IPA_100kGy
GO IPA 200 GO_IPA_200kGy
GO IPA 300 GO_IPA_300kGy
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
3
hyd ophilic and unc ionalized GO. In he educ ion o GO o GO,
oxygen-con aining unc ional g oups, including hyd oxyl, ca boxyl, and
epoxide, a e elimina ed. These g oups enhance in e laye spacing and
plana s abili y in GO. Thei elimina ion dis up s egula i y and induces
heigh ened s uc u al diso de , culmina ing in a mo e w inkled o un-
dula ing mo phology [5]. The educ ion p ocess pa ially eins a es he
sp² ca bon ne wo k, albei incomple ely. This incomple e epai gene -
a es in e nal s ess and localized impe ec ions, esul ing in he bending
o ippling o he nanoshee s in he inal ilm con igu a ion. Du ing he
p ocesses o ilm o ma ion and sol en e apo a ion, he mo e hyd o-
phobic GO shee s exhibi dis inc agg ega ion and collapse beha io s
compa ed o he hyd ophilic GO shee s. This equen ly leads o olding
and w inkling, impa ing a mo e ex u ed su ace o GO ilms. The
elimina ion o oxygen g oups du ing educ ion equen ly esul s in a
olume ic con ac ion, which may induce mechanical s ess and de o m
he plana s uc u e, hence causing wa iness.
The EDX analysis esul s o he oxida ion/ educ ion p ocesses o GO
and GO a e p esen ed in Table 2.
F om he EDX esul s we con i med he p esence o bo h O and C
a oms in bo h samples (GO and GO) bu wi h a ia ions in he a omic
%. Oxida ion/ educ ion o GO in ai and IPA did no signi ican ly in-
luence he C a % o O a % signi ican ly, bu a he small shi s we e
no iced. This could be he consequence o a laye ed s uc u e o he ee-
s anding ilms, a highly oxidized su ace o GO, and low gamma i a-
dia ion ene gy o e icien ly make signi ican changes on he GO su ace.
Gamma i adia ion in ai gene a es oxidizing adicals (like
•
OH and
O₂
•
⁻), which can e-oxidize GO o p e en he ull educ ion p ocess.
Oxygen in ai apidly eac s wi h hyd a ed elec ons and adicals,
Fig. 1. SEM/EDS analysis o GO ea ed unde di e en gamma i adia ion dosages: a) GOp, b) GO_ai _50 kGy, c) GO_ai _100 kGy, d) GO_ai _200 kGy, e) GO_ai _300
kGy, ) s a is ical ep esen a ion o he C a % and O a % based on he EDS analysis, g) GO_IPA_50 kGy, h) GO_IPA_100 kGy, i) GO_IPA_200 kGy, and j)
GO_IPA_300 kGy.
Fig. 2. SEM/EDS analysis o GO ea ed unde di e en gamma i adia ion dosages: a) GOp, b) GO_ai _50 kGy, c) GO_ai _100 kGy, d) GO_ai _200 kGy, e)
GO_ai _300 kGy, ) s a is ical ep esen a ion o he C a % and O a % based on he EDS analysis, g) GO_IPA_50 kGy, h) GO_IPA_100 kGy, i) GO_IPA_200 kGy, and j)
GO_IPA_300 kGy.
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
4
educing he a ailabili y o educing agen s ha could a ge GO oxygen
g oups. On he o he hand, IPA does p oduce some educing species, bu
no as e ec i ely as wa e would wi h a educing sca enge [14]. The
balance be ween educing and oxidizing species in IPA +ai a o s mild
o pa ial educ ion. Also, some oxygen g oups, especially ca boxylic
acids a he edges, a e chemically mo e s able and equi e s onge
educ ion condi ions o be emo ed.
In he GO samples, a mo e p onounced educ ion e ec han
oxida ion was seen in bo h media (ai , IPA) compa ed o GOp (Table 2).
This phenomenon can be unde s ood h ough he in e ac ion be ween
he p ope ies o he o iginal ma e ials, adia ion chemis y, and he
cha ac e is ics o he su ounding media. The GO possesses a educed
amoun o oxygen-con aining unc ional g oups in compa ed o GO.
Consequen ly, unde gamma i adia ion, he eac i e oxygen species o
adioly ic en i ies p oduced in ai o IPA may ha e ew a ailable
oxida ion si es, leading o es ic ed oxida ion. Thus, he adia ion-
induced elimina ion o esidual oxygen g oups p e ails, enhancing
u he educ ion. Gamma ays p oduce seconda y elec ons and induce
bond clea age. In GO, esidual C–O, C =O, o O–C =O g oups a e
p one o clea age upon i adia ion. This leads o deoxygena ion a he
han he p oduc ion o new oxygen g oups. In IPA, adiolysis gene a es
educing species, and hese educing adicals a e mo e e icien a
elimina ing oxygen-con aining g oups, especially in p e iously educed
GO, hence imp o ing he educ ion p ocess. As a esul , GO can
con inue o expe ience signi ican bond scission and deoxygena ion,
ende ing educ ion he p e ailing p ocess.
3.2. FTIR in es iga ion
The FTIR cha ac e iza ion was used o cha ac e ize di e en unc-
ional g oups o GO and GO ma e ials. The GOp showed a ypical FTIR
Table 2
EDX analysis o he oxida ion/ educ ion p ocesses o GO and GO samples unde
i adia ion.
Sample C
a omic
%
O
a omic
%
Sample C
a omic
%
O
a omic
%
GOp 66.8 33.2 GOp 81.6 18.4
GO_ai _50
kGy
66.9 33.1 GO_ai _50
kGy
84.47 15.53
GO_ai _100
kGy
67.7 32.3 GO_ai _100
kGy
83.74 16.26
GO_ai _200
kGy
67.1 32.9 GO_ai _200
kGy
81.14 18.86
GO_ai _300
kGy
67.2 32.8 GO_ai _300
kGy
80.6 19.4
GO_IPA_50
kGy
67.6 32.4 GO_IPA_50
kGy
84.87 15.13
GO_IPA_100
kGy
67.8 32.2 GO_IPA_100
kGy
85.19 14.81
GO_IPA_200
kGy
68.6 31.4 GO_IPA_200
kGy
84.48 15.52
GO_IPA_300
kGy
68 32 GO_IPA_300
kGy
85.9 14.1
Fig. 3. The FTIR spec a o GO and GO ea ed unde di e en gamma i adia ion dosages (50, 100, 200, and 300 kGy): a) GO in ai , b)GO in IPA, c) GO in ai , and
d) GO in IPA.
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
5
spec um o GO (Fig. 3, black cu e) wi h bands loca ed in a ange om
2500 o 3500 cm
-1
due o ca boxyl O
–
H s e ching, 1716 cm
-1
om C =
O o ca boxyl g oups, 1609 cm
-1
om C =C s e ching o unoxidized
g aphi ic domains, 1222 cm
-1
om C
–
OH s e ch o alcohol g oup and
1036 cm
-1
om C
–
O s e ch o C
–
O-C [16]. Upon oxida ion in ai
unde di e en gamma i adia ion dosages, he band in ensi ies we e
educed, whe e he lowes in ensi ies we e no iced in samples ea ed a
200 and 300 kGy (Fig. 3a). Upon educ ion in IPA (Fig. 3b), he in-
ensi ies o he peaks associa ed wi h he oxygen-con aining unc ions o
GO we e diminished in compa ison o he peak in ensi ies o GOp. This
demons a ed he e ec i e educ ion o GO by gamma i adia ion.
Howe e , he peaks did no diminish, sugges ing ha GO was no
en i ely educed by gamma i adia ion, indica ing he pe sis ence o
ce ain unc ional g oups [15,44].
In a case o GO samples, he p is ine GO showed as he mos
p ominen band he one om C =C o unoxidized g aphi ic domains
loca ed a 1603 cm
-1
(Fig. 3c, black cu e), con i ming he GO ma e ial
unde gamma ea men , wi hou any oxygena ed unc ional g oups.
Upon oxida ion, he band a 1603 cm
-1
ge s mo e p ominen , sugges ing
a mo e a anged su ace o he GO upon i adia ion, while he ise o
he small band a 1224 cm
-1
sugges he p esence o C
–
OH s e ch o
alcohol g oups (Fig. 3c). The same obse a ions we e no iced o he
educed samples (Fig. 3d) wi h he addi ion o a wide band in a ange
om 2500 o 3500 cm
-1
om he ca boxyl O
–
H s e ching mode in
samples GO_IPA_50 kGy and GO_IPA_100 kGy.
3.3. Raman in es iga ion
Raman spec a o he ee-s anding highly lexible GO and GO ilms,
ea ed a di e en gamma i adia ion dosages in ai and IPA medium,
wi h de ailed analysis a e shown in Fig. 4 and 5, espec i ely. Raman
spec a o all samples show he b oad/in ense D band a ~1343 cm
-1
,
and G band a ~1590 cm
-1
as well as low in ensi y 2D band a ~2700
cm
-1
me ged wi h D +G band (Fig. 4a,b, and Fig. 5a,b) [19]. To
calcula e he I
D
/I
G
and I
2D
/I
G
a ios and es ablish he peak posi ions and
FWHM, decon olu ed Raman spec a (Fig. S1, Fig. S2, Fig. S3, Fig. S4)
we e u ilized [10]. Fo all GO samples i adia ed in ai and IPA, Raman
spec a (Fig. S1, Fig. S2) we e decon olu ed wi h 4 +3 o 3 +3 peaks
assigned as A, D, G, B, 2D, D +G and 2D’, whe e he p esence o A, B and
2D’ bands con ibu e o he de ec le el o he ma e ial which we e
no ed mos ly in oxidized samples [12]. In GO samples, he e we e no
addi ional A and B de ec bands, bu aside om D, G, 2D, D +G, and 2D’
bands, occasionally he D’ band was no iced, wi h decon olu ion wi h
mos ly 2 +2 and 2 +3 bands (Fig. S3, Fig. S4).
In he GO samples, he D and G band posi ions ha e no changed
upon gamma i adia ion, while he ull wid h a hal maximum (FWHM-
Г
) alues ha e d opped. The FWHM o he D band (
Г
D
), dec eased when
compa ed o GOp in ai and IPA medium (Fig. 4c) which can be a
con i ma ion o he e ec o gamma i adia ion on he s uc u al
changes on a nano le el, pa icula ly ela ed o de ec densi y and dis-
o de in he ca bon la ice in GO ma e ial. A na owe D band indica es a
g ea e uni o mi y in de ec ypes and he de elopmen o la ge and
mo e o ganized sp² domains, ega dless o he pe sis ence o some de-
ec s such as edge-like de ec s wi h a na owe ib a ional signa u e. The
Г
G
alues (Fig. 4d) mos ly mani es a dec ease, sugges ing a possible
small es o a ion o g aphi ic s uc u e and inc eased c ys allini y. Only
samples GO_ai _100 kGy and GO_ai _200 kGy showed an inc ease in a
Г
G
alues, as a esul o he g ea e s uc u al diso de and dis u bance in
sp² domains caused by oxida ion. The I
D
/I
G
and I
2D
/I
G
a ios o GO
samples in ai and IPA inc ease upon oxida ion/ educ ion as an ou come
o he su ace changes (Fig. 4e, ). The dis up ion o he sp² domains
inc eases he numbe o sp³-hyb idized de ec s, and as a consequence, d-
band in ensi y inc eases and consequen ly I
D
/I
G
a io. Gamma i adia-
ion can also p omo e eo ganiza ion esul ing in a mo e p onounced 2D
band in compa ison o he G band, leading o highe alues o I
2D
/I
G
.
Raman spec a o GO ee-s anding ilms, bo h p is ine and ea ed
unde gamma i adia ion in ai and IPA, a e p esen ed in Fig. 5a,b.
In bo h cases, a p esence o D +G band was no iced, in addi ion o
common D, G, and 2D bands. The decon olu ion
The dec ease in he FWHM o he D (
Г
D
) and G (
Г
G
) bands in ee-
s anding ilms o GO ollowing gamma i adia ion, when compa ed o
GOp, indica es enhanced s uc u al o de and diminished de ec densi y
(Fig. 5c, d) [10]. A educ ion in he
Г
D
poin o a mo e uni o m dis i-
bu ion o impe ec ions o a d op in de ec densi y. Gamma i adia ion
e ec may also esul in he elimina ion o ce ain oxygen unc ional
g oups and he pa ial econs i u ion o sp² ca bon ne wo ks, which can
es o e he la ice, leading o na owe D bands. The G band is associa ed
wi h C–C bond s e ching in sp² ca bon egions. The e o e, a educed
Г
G
signi ies a mo e consis en and o ganized sp² domain s uc u e. By
calcula ing he I
D
/I
G
a io, an inc ease in alues was obse ed in bo h
oxidized and educed samples (Fig. 5e). Oxida ion in oduces epoxy,
hyd oxyl, ca bonyl, and ca boxyl g oups o he su ace o GO. These
g oups dis u b he conjuga ed sp² hyb idized ca bon amewo k, ans-
o ming some sp² ca bons in o sp³-hyb idized si es. The ollowing dis-
up s he
π
-conjuga ion, esul ing in mo e localized de ec s. The gamma
i adia ion and inco po a ion o unc ional g oups also induce local
s ain, bending, and dis o ion o he g aphene shee , leading o he
p oduc ion o opological de ec s. Addi ionally, oxida ion could damage
ca bon a oms a he bounda ies o wi hin he la ice, c ea ing acancies
and dangling bonds. Upon educ ion, he ele a ion in de ec le els in
GO upon educ ion is mainly a ibu able o he incomple e and
equen ly incomple e elimina ion o oxygen-con aining g oups and he
dis u bance o he ca bon la ice du ing he educ ion p ocess (Fig. 5e).
Al hough educ ion seeks o eins a e he g aphene-like s uc u e by
elimina ing unc ional g oups, i equen ly c ea es no el de ec ypes
[10].
3.4. XRD measu emen s
Fo he XRD measu emen s we ha e chosen GOp and GOp samples,
as well as samples i adia ed a high gamma dosage o 300 kGy
(GO_ai _300 kGy, GO_IPA_300 kGy, GO_ai _300 kGy, and GO_IPA_300
kGy).
The GOp sample shows he cha ac e is ic low-angle (001) e lec ion
a ~11.82◦(2θ), associa ed wi h expanded in e laye spacing p oduced
by oxygen unc ional g oups and in e cala ed wa e (Fig. S5). This peak
is ela i ely sha p compa ed wi h he i adia ed GO spec a, indica ing
mo e egula lamella s acking [31,34]. By con as , when GO is i a-
dia ed in IPA he XRD e olu ion indica es educ i e deoxygena ion and
es acking. A high dose such as 300 kGy, he GO (001) peak ma kedly
a enua es and a b oade (002)- ype ea u e g ows nea he g aphi ic
egion (~22.87◦), signi ying emo al o oxygen g oups, expulsion o
in e cala ed wa e , and pa ial eco e y o close sp² s acking. The IPA
medium p omo es educing adioly ic species (sol a ed elec ons, H•)
and sca enges •OH, which explains he end owa d deoxygena ion and
he appea ance o g aphi ic (002) in ensi y in IPA-i adia ed GO. When
GO is γ-i adia ed in ai , he XRD pa e n e ol es in a way consis en
wi h addi ional oxida i e modi ica ion and diso de . A he high dose o
300 kGy, he (001) peak diminishes due o adia ion-induced oxida ion
and de ec gene a ion, dis up ing egula s acking and inc easing
s uc u al diso de [34].
The GOp lacks he p ominen low-angle (001) GO peak and ins ead
exhibi s a b oade , weake ea u e nea he highe -angle posi ion ypical
o g aphi ic (002) s acking a ~25.07◦(2θ) (Fig. S5) [22,57]. I e lec s
pa ial es o a ion o sp² domains and close in e laye spacing wi h
esidual u bos a ic diso de . Upon i adia ion in IPA a high dose (300
kGy) de ec c ea ion ( acancies, holes, edge damage) can b oaden and
educe he (002) in ensi y despi e low oxygen con en . When GO is
i adia ed in ai , oxida i e a ack and gene a ion o su ace de ec s
domina e: he (002) ea u e b oadens and may shi , and backg ound
sca e ing inc eases, indica ing la ice dis up ion and pa ial
e-oxida ion/ unc ionaliza ion o inc eased u bos a ic diso de [1].
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
6
Fig. 4. Raman analysis o GO ee-s anding ilms a di e en gamma i adia ion dosages: a) in ai , b) in IPA, c) FWHM D band, d) FWHM G band, e) I
D
/I
G
, and )
I
2D
/I
G
.
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
7
Fig. 5. Raman analysis o GO ee-s anding ilms a di e en gamma i adia ion dosages: a) in ai , b) in IPA, c) FWHM D band, d) FWHM G band, e) I
D
/I
G
, and )
I
2D
/I
G
.
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
8
XRD is sensi i e o long- ange o de . A low and in e media e doses
(50, 100, 200 kGy), based on ou p e ious expe ience, he s uc u al
changes in GO/ GO a e ela i ely sub le. The in e laye peak b oad-
ening and in ensi y dec ease a e p og essi e bu no d ama ic, so he
di e ences be ween consecu i e doses a e no easily dis inguishable in
XRD pa e ns. On he con a y, a 300 kGy, γ-i adia ion p oduces he
s onges modi ica ion o c ys allini y and s acking o de . The e o e, i
p o ides a clea con as compa ed o he p is ine ma e ials (GO and
GO). This allows di ec demons a ion o he i adia ion impac . Also,
o he cha ac e iza ions (e.g., Raman, FTIR, and XPS) we e employed o
ollow he g adual chemical/s uc u al changes a 50, 100, and 200 kGy.
XRD was used speci ically o con i m and highligh he end-poin e ec
o i adia ion on long- ange o de ing. The e o e, including all i adia-
ion doses in he XRD plo would o e c owd he igu e wi hou adding
signi ican new in o ma ion, since he peak e olu ion is g adual.
Showing only p is ine and he mos i adia ed samples p o ides a clea ,
ep esen a i e compa ison wi hou edundancy.
3.5. Wa e con ac angle measu emen s
Measu emen s o he wa e con ac angle (CA) we e conduc ed o
assess he hyd ophobic o hyd ophilic p ope ies o he p epa ed GO and
GO ee-s anding lexible ilms. Commonly, ha he su aces wi h
con ac angles ≥90◦a e classi ied as hyd ophobic, o wa e - epellen
[30]. Table 3 ep esen s he con ac angle measu emen s o GO and
GO gamma- ea ed samples.
The CA alues a e simila o GO and GO in ai ac oss all doses.
Sligh ly lowe CA in GO sugges s ma ginally inc eased hyd o-
philici y—possibly due o su ace es uc u ing o in oduc ion o pola
g oups despi e educ ion. Gamma i adia ion in an ai a mosphe e does
no signi ican ly al e su ace we abili y. GO shows g ea e changes in
CA wi h inc easing dose in IPA om 34◦ o 63◦, indica ing a shi om
good hyd ophilic o low hyd ophobic beha io . This sugges s ha
educ ion is occu ing (loss o oxygen-con aining g oups). GO in IPA
shows consis en ly highe CA alues han o GO, indica ing mo e hy-
d ophobic cha ac e , which is expec ed o educed ma e ials. The
dec easing end in GO CA om 54◦ o 43◦may e lec su ace oxida-
ion o eo ganiza ion due o IPA-media ed i adia ion.
3.6. EMI shielding measu emen s
Fig. 6 shows he o al shielding e ec i eness plo s o GO samples
i adia ed in ai , IPA, and GO i adia ed in he same media, a all
applied doses. EMI SE o GO_IPA_300 kGy sample could no be measu ed
due o isible up u es o he ma e ials. Samples o GO ai and GO IPA
(Figуре 6 a, b) show a low EMI SE. A small imp o emen was no ed a e
GO was i adia ed in ai a a dose o 200 kGy, om 0.31 dB o 0.52 dB,
while i adia ion in IPA esul ed in a lowe ing o EMI SE o 0.09 dB. On
he con a y, educed ee-s anding GO i adia ed ai showed EMI SE
abo e 20 dB, sugges ing hei excellen shielding pe o mance. Samples
i adia ed wi h 50 kGy showed he highes alues, along wi h he one
i adia ed a 300 kGy, while he lowes EMI SE was measu ed o he one
i adia ed a 200 kGy. In he case o GO i adia ed in IPA, doses o 50,
100, and 200 kGy showed simila e ec s on EMI SE, and all h ee
samples showed a simila SE
T
(be ween 26 and 27 dB).
In Fig. 7, he componen s o o al shielding e ec i eness, dissipa ion
(L
D
), and misma ch loss (L
M
) a e p esen ed. In he case o GO gamma
i adia ed samples (Fig. 7a-d), he majo po ion o he o al shielding
e ec i eness is due o L
D
, and wi h negligible L
M
, while in he case o
GO samples (Fig. 7e-h), bo h L
D
and L
M
a e p esen ; howe e , he L
D
componen is he dominan one. The L
M
alues in GO gamma-i adia ed
samples a e signi ican ly highe han o L
M
in gamma-i adia ed GO
samples. These esul s indica ed ha he main mechanism o EMW
a enua ion is abso p ion, which is a cha ac e is ic ai o s a e-o - he-
a shielding ma e ials. Resul s o GOp and GOp (Fig. S6) showed
a e age o al shielding e iciency o GOp o be 0.36002±0.02458 dB
(3.20294±0.27647 %), and 18.69275±0.77286 dB (88.23828±1.01234
%) o GO.
By compa ing he EMI SE o all samples, i is no iced ha he highe
applied dosages o gamma i adia ion con ibu e highe o he EMI SE o
GO i adia ed in ai , while i adia ion in IPA imp o es EMI SE a lowe
applied dosages (50 and 100 kGy) (Fig. 8a, b).
In he case o GO samples, a sligh imp o emen in EMI SE was
obse ed a e gamma i adia ion a 300 kGy (Fig. 8c), 95.5 %,
compa ed o 94.5 o 94.8 % calcula ed o o he dosages. Al hough he
SE
T
alues sligh ly inc eased a 300 kGy, hese esul s showed a su -
p ising e ec on EMI SE, conside ing ha high-dose gamma i adia ion
induces de ec o ma ion in g aphene-based nanoma e ials [21,24], i
was expec ed ha gamma i adia ion migh a ec he nega i e EMI
shielding pe o mances o GO ma e ials. These esul s could be
explained by he o ma ion o c oss-laye b idges be ween g aphene
shee s, as p e iously obse ed a nano ubes and he c ea ion o an
addi ional pa h o signal a enua ion.
EMI SE o GO and GO is ma kedly a ec ed by hei oxida ion de-
g ee, de ec densi y, and elec ical conduc i i y. GO is ex ensi ely oxi-
dised, ea u ing a a ie y o oxygena ed unc ional g oups (e.g.,
hyd oxyl, epoxy, ca boxyl) ha in e e e wi h he
π
-conjuga ed ne wo k.
These g oups diminish elec ical conduc i i y, ende ing GO an ine -
ec i e EMI shield unless combined wi h conduc i e addi i es o u ilised
in mul ilaye composi es. Howe e , oxygen g oups acili a e in e acial
pola isa ion, which may lead o dielec ic loss and abso p ion- ype
shielding. In GO, mode a e de ec le els can imp o e EMI shielding
by ampli ying mul iple sca e ing and e lec ion o elec omagne ic
wa es, as well as enhancing pola isa ion cen es o dielec ic loss.
Excessi e laws can impai conduc i i y and diminish e lec ion-
domina ed shielding. Elec ical conduc i i y is he main ea u e o
e lec ion-domina ed elec omagne ic in e e ence shielding. GO,
pa icula ly when adequa ely educed h ough he mal o chemical
me hods, eins a es sp² ca bon ne wo ks, he e o e ma kedly enhancing
conduc i i y. Inc eased conduc i i y esul s in enhanced e lec ion o
elec omagne ic wa es and imp o ed shielding e iciency, especially
wi hin he highe - equency mic owa e spec um. Gamma i adia ion
can p omo e w inkling o olding o GO shee s due o adiolysis-
induced s ain, which inc eases su ace oughness, mul iple e lec ion
pa hways, and aps and a enua es EM wa es mo e e ec i ely [8,20,35,
42,53].
Compa ed o non-i adia ed samples (GO and GO), gamma i adi-
a ion imp o ed he EMI SE o ee-s anding ilms i adia ed in he ai
and IPA a all applied doses. The e ec s o applied doses on EMI SE a e
no signi ican . Imp o emen o EMI SE ee-s anding GO and GO by
gamma i adia ion is associa ed wi h wo main e ec s o gamma ays
owa ds g aphene shee s:
•c ea ing c oss-laye b idges be ween he shee s and O- unc ional
g oups, emo ing by i adia ion in IPA, i ensu ed cha ge a eling
ac oss he laye and cha ge hopping om one shee o ano he ,
enhancing he conduc ion loss [4];
Table 3
CA measu emen s o GO and GO gamma- ay- ea ed samples.
Sample CA (◦) Sample CA (◦)
GOp 61 GOp 38
GO_ai _50kGy 48 GO_ai _50kGy 44
GO_ai _100kGy 49 GO_ai _100kGy 47
GO_ai _200kGy 46 GO_ai _200kGy 46
GO_ai _300kGy 46 GO_ai _300kGy 44
GO_IPA_50kGy 34 GO_IPA_50kGy 54
GO_IPA_100kGy 53 GO_IPA_100kGy 49
GO_IPA_200kGy 63 GO_IPA_200kGy 45
GO_IPA_300kGy 55 GO_IPA_300kGy 43
J.P. Filipo ic e al.
Chemical Enginee ing Jou nal Ad ances 24 (2025) 100873
9
