Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of Chemistry 2021

Supplementary Information

Shape tailoring of AgBr microstructures: effect of the cations of different bromide sources

and the applied surfactants

Zsejke-Réka Tótha,b, Zsolt Papb,c,d, János Kissa, Lucian Baiab,e, Tamás Gyulavária, Zsolt

Czekesb,f, Milica Todeab,g, Klára Magyarib,c, Gábor Kovácsb,c,*, Klara Hernadia,h

a – Department of Applied and Environmental Chemistry, University of , Rerrich Béla tér

1, HU-6720, Szeged, ;

b – Nanostructured Materials and Bio-Nano-Interfaces Center, Institute for Interdisciplinary

Research on Bio-Nano-Sciences, Babeș-Bolyai University, Treboniu Laurian 42, RO-400271,

Cluj-Napoca, ;

c – Institute of Environmental Science and Technology, , Lajos krt.

103, HU-6720, Szeged, Hungary;

d – Institute of Research-Development-Innovation in Applied Natural Sciences, Babes-Bolyai

University, Fântânele 30, RO-400294, Cluj-Napoca, Romania;

e – Faculty of Physics, Babeș–Bolyai University, M. Kogălniceanu 1, RO-400084, Cluj–Napoca,

Romania;

f ‒ Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Clinicilor 5–7, RO-

400006, Cluj-Napoca, Romania;

g – Iuliu Hatieganu University of Medicine and Pharmacy, Faculty of Medicine, Victor Babeş 8,

RO-400012, Cluj-Napoca, Romania.

h – Institute of Physical Metallurgy, Metal Forming and Nanotechnology, University of ,

3515 Miskolc-Egyetemváros, Hungary * Corresponding author: [email protected], [email protected] (G. K.) Adsorption measurement:

Experimental:

The adsorption measurement was investigated using a 100 mL beaker. The concentration of MO was 125 μM, while the concentration of the suspension was 1 g · L-1. After 15 minutes of ultrasonication (where the suspension formed), the beaker was covered with aluminum foil (for eliminate any light photon). The adsorption measurement was taken 2 hours with continuous stirring. The sampling was in the first 30 minutes in 5-minutes interval, in the second 30 minutes in 10-minutes interval, and in the last 1 hour in 20-minutes interval.

An Analytic Jena Specord 250 plus spectrophotometer was used to analyzed to amount of the

adsorbed MO.

AgBr_CsBr_NØ 0 min AgBr_LiBr_PVP 0 min a 5 min b 5 min 10 min 10 min 15 min 15 min 20 min 20 min 25 min 25 min 30 min 30 min ) ) . 40 min . 40 min u u . . a a

( 50 min 50 min (

e e c 60 min c 60 min n n a 80 min a 80 min b b r r o 100 min o 100 min s s b 120 min b 120 min A A

250 300 350 400 450 500 550 600 250 300 350 400 450 500 550 600  (nm)  (nm) 0 min AgBr_NaBr_CTAB 0 min AgBr_KBr_SDS c 5 min d 10 min 10 min 15 min 15 min 20 min 20 min 25 min 25 min 30 min 30 min 40 min ) ) . u

. 40 min 50 min u . a ( a

50 min ( 60 min

e e c c

n 60 min 80 min n a a b 80 min 100 min b r r o s 100 min o 120 min s b b

A 120 min A

250 300 350 400 450 500 550 600 250 300 350 400 450 500 550 600  (nm)  (nm)

Figure S1: Adsorption curves of AgBr samples: (a) AgBr_CsBr_NØ; (b) AgBr_LiBr_PVP; (c)

AgBr_KBr_SDS and (d) AgBr_NaBr_CTAB (model pollutant: methyl orange) before after AgBr (200) AgBr_CsBr_N_after (220) AgBrO3 a b (111) AgBr_CsBr_N AgBr_RbBr_N_after

AgBr_KBr_N_after AgBr_RbBr_N ) ) . . u u . .

a AgBr_NaBr_N_after a ( (

y y t

AgBr_KBr_N t i i s s n Ø n e e t t n N n I AgBr_NaBr_N I @AgBrO ; #AgBr AgBr_LiBr_N_after 3 #AgBr, @Ag @AgBrO AgBr_LiBr_N 3 @AgBrO #AgBr @Ag 3 AgBr_HBr_N_after (202) AgBr_HBr_N

20 25 30 35 40 45 50 20 25 30 35 40 45 50 2 2

@AgBrO AgBr (200) 3 @AgBrO3 (220) c d AgBr_CsBr_SDS_after (111) AgBr_CsBr_SDS AgBr_RbBr_SDS_after AgBr_RbBr_SDS )

. AgBr_KBr_SDS_after ) . u . u a . ( a

( y

t y

i AgBr_KBr_SDS t S s i s n AgBr_NaBr_SDS_after e n D

t @AgBrO ; #AgBr e 3 t n #AgBr, @Ag S I n

AgBr_NaBr_SDS I @AgBrO 3 @AgBrO3 #AgBr @Ag AgBr_LiBr_SDS AgBr_LiBr_SDS_after

AgBr_HBr_SDS AgBr_HBr_SDS_after 20 25 30 35 40 45 50 20 25 30 35 40 45 50 2 2 AgBr (200) AgBr_RbBr_CTAB_after AgBrO (220) 3 e f (111) AgBr_CsBr_CTAB AgBr_KBr_CTAB_after AgBr_RbBr_CTAB ) . ) AgBr_NaBr_CTAB_after . u . u . a a (

( B

y

AgBr_KBr_CTAB y t i t A i s s

n AgBr_LiBr_CTAB_after n T e @AgBrO ; #AgBr e t (202) 3 t n #AgBr, @Ag C n I AgBr_NaBr_CTAB I @AgBrO3 @AgBrO #AgBr 3 AgBr_LiBr_CTAB @Ag #AgBr AgBr_HBr_CTAB_after #AgBr, @Ag AgBr_HBr_CTAB #AgBr @Ag

20 25 30 35 40 45 50 20 25 30 35 40 45 50 2 2

Figure S2: XRD patterns of AgBr photocatalysts prepared with different alkali metals (Li+, Na+,

K+, Rb+, and Cs+) and H+ obtained (a, b) without surfactant (NØ) and by using (c, d) SDS or (e,

f) CTAB, (left column) before and (right column) after photocatalytic degradation 1.0 1.0 a AgBr_HBr_SDS b AgBr_LiBr_SDS

0.9 AgBr_NaBr_SDS 0.9 AgBr_KBr_SDS AgBr_RbBr_SDS ) ) . . u u . . 0.8 AgBr_CsBr_SDS 0.8 a a ( (

e e c c n n a a b b r r o o s s b b 0.7 0.7 A A

AgBr_HBr_CTAB AgBr_LiBr_CTAB 0.6 0.6 AgBr_NaBr_CTAB AgBr_KBr_CTAB AgBr_RbBr_CTAB AgBr_CsBr_CTAB 0.5 0.5 300 400 500 600 700 800 300 400 500 600 700 800  (nm)  (nm) c 1.00

) 0.95 . u . a (

e c n a b r

o 0.90 s b

A AgBr_HBr_N_after AgBr_HBr_SDS_after AgBr_HBr_CTAB_after 0.85 AgBr_NaBr_N_after AgBr_NaBr_SDS_after AgBr_KBr_CTAB_after AgBr_CsBr_N_after AgBr_CsBr_SDS_after 0.80 300 400 500 600 700 800  (nm)

Figure S3: Diffuse reflectance spectra of the silver-halides obtained in the presence of different alkali metals (Li+, Na+, K+, Rb+ and Cs+) and H+ obtained with (a) SDS, (b) with CTAB, and (c)

after degradation process. Figure S4: Distribution of AgBr particles sizes based on SEM micrographs from Fig. 6 Selection of the model pollutant: Material The phenol degradation was taken under UV light degradation, and the MO degradation was taken under visible (parameters shown in main manuscript) and UV light degradation.

Degradation parameters: The same equipment was used for UV degradation only the reactor was thermostated by distilled water and irradiated by 6×6 W (λmax = 365 nm) UV lamps. The concentration change of MO was detected same as after visible light irradiation. The decrease in phenol concentration was measured by Merck-Hitachi L-7100 high-pressure liquid chromatography with Merck-Hitachi L-4250 UV-Vis detector (λdetection = 210 nm) and a

Lichrospher Rp 18 column (eluent: 50:50 = MeOH:H2O). Results and discussions In the main article, we have shown that the Br-source and the surfactant can influence the morpho-structural and optical properties of the as-obtained AgBr. Therefore, to investigate the activity differences between these photoactive materials, we have chosen two different model pollutants: i.) phenol, a by-product, and a precursor of the pharmaceutical industry, resulting in more than 28 intermediates through its photocatalytic degradation1 and ii.) MO, which is a well-known organic dye, used mostly in the textile industry. In the case of MO, we have used two different lamp sources, UV (λmax = 365 nm) and Vis (λ >400 nm), while for phenol degradation, only UV lamps irradiation were applied (generally, the degradation efficiencies of the phenol are lower in visible light irradiation). For further investigations, we have used AgBr_NaBr based samples. The reason for this selection was that the AgBr_NaBr_PVP and the AgBr_NaBr_NØ had the lowest band gap energy values in comparison with all samples. The AgBr_NaBr_SDS has an abnormal photocatalytic performance, because compared with MO degradation would be excepted a much higher degradation. The reason of the low degradation value can be lies in Ag nanoparticles or other silver-based material deposition. Noticeable, that formation of these materials affected the degradation of model pollutant, but the effect quality (disadvantages or advantages) is questionable. Comparing with the degradation of the methyl orange, the oxidation of the phenol was less efficient (Fig. S4), which can be attributed to the fact that phenol has a more stable aromatic structure, and it is a poorly adsorbing agent in comparison with MO. The trend of photocatalytic degradation yields (PVP=CTAB>NØ> SDS) is the opposite, compared to the one observed in the case of (111)/(200) ratio (Fig. 3), causing an increased adsorption rate of the degradation intermediates on the surface, thereby reducing the degradation yield of phenol2. Besides, in the literature, methyl orange is more widely used as a model pollutant for testing AgBr (44 vs. 152 articles for phenol and methyl orange, respectively, according to a search on Scopus using AgBr + model pollutant keywords, 26.10.2020). In the present work, we focused on the photocatalytic degradation using visible light irradiation of methyl orange because the decomposition yields under visible light are higher than the results with UV light irradiation, and this promises them to be used in visible light processes either indoors or outdoors (using the sunlight) while improving their environmentally friendly character.

Figure S5: Model pollutant/lamp selection by using AgBr_NaBr photocatalysts 1.6 10 min 20 min 30 min 1.4 40 min C-C (ring) 50 min 1631 N=N 60 min 1384 80 min 1.2 100 min 120 min after adsorption 1200 SO2- 3 before degradation 1124 after degradation 1.0 1038 1007 ) .

u 0.8 . a ( y t i s n e t

n 0.6 I

0.4

0.2

0.0

-0.2 2000 1500 1000 500 Wavenumber (cm-1)

Figure S6: IR spectra of AgBr_NaBr_PVP after degradation processes 120 - best by using different surfactant AgBr_LiBr_PVP - best by using different bromide source AgBr_HBr_NØ - best in both cases AgBr_NaBr_CTAB 100 AgBr_KBr_SDS AgBr_HBr_PVP

) AgBr_KBr_PVP 80 M AgBr_RbBr_PVP μ (

e AgBr_CsBr_PVP g n a r

o 60 l y t e m C 40

20

0 0 20 40 60 80 100 120 Irridation time (min)

Figure S7: Degradation curve of MO degradation for the most efficient samples.

References:

1. Dang TTT, Le STT, Channei D, Khanitchaidecha W and Nakaruk A. Photodegradation mechanisms of phenol in the photocatalytic process. Research on Chemical Intermediates. 2016;42(6):5961-74.

2. Tóth Z-R, Kovács G, Hernádi K, Baia L and Pap Z. The investigation of the photocatalytic efficiency of spherical

gold nanocages/TiO2 and silver nanospheres/TiO2 composites. Separation and Purification Technology. 2017;183:216-25.