S.N. Ghalebin, A. Bezaatpour, M.H. Sadr et al.
Journal of Molecular Liquids 328 (2021) 115338
distilled (DD) water to adjust pH = 6. After that, the suspension was di-
luted with 20 mL of ethanol and placed in autoclave reactor at 170 °C for
visible light irradiation. Progress of the reaction was monitored by gas
chromatography (GC-FID).
2
4 h. To more purification, the obtained sample was washed several
time with acetone and dried in oven at 90 °C.
3
. Results and discussion
2.4. Preparation of 1,4-bis(2-formylphenoxy)butane
3.1. Characterization of photocatalyst
1
,4-bis(2-formylphenoxy)butane was synthesized according to the
literature [25]. For this purpose 300 mmol 2-hydroxybenzaldehyde
and 150 mmol K CO was stirred in 150 mL of DMF. Then 32.4 g
150 mmol) of 1,4-dibromobutane (dissolved in 60 mL DMF) was
added dropwise to the desired mixture. The mixture was stirred for
Fig. 1 shows the FT-IR spectrum of GO, rGO, CuM and rGO/CuM30.
−
1
The bands at 1053, 1170, 1600, 1707, 2930, and 3400 cm
that
2
3
assigned to C-O-C, C–O, C_C, C_O, C–H, and O–H respectively for GO
27]. In the case of rGO, the broad peak of the O–H group decreased sig-
(
[
−1
nificantly. The peak at 1626 cm can attributed to the stretching vibra-
tion of C_N, in rGO/CuM30 and CuM30 (Fig. 1c and d) [28]. Bands
1
3
2 h at 170 °C. Then the stirring was continued at 25°C for 6 h. Then
00 mL distilled water was added to mixture and placed in the refriger-
ator for 1 h. The formed solid was obtained via filtration and washed
with 700 mL of distilled water. Finally the obtained solid was recrystal-
lized in ethanol and dried in vacuum. Yield: 34.7 g (78%), m.p:
−1
around 2900, 485 and 525 cm are assigned to Alph–CH, Cu–O and
Cu–N bands in the metal complex respectively [29].
Fig. 2 shows the survey X-ray photoelectron spectroscopy (XPS) of
rGO/CuM30. Showing contributions of C1s, N1s, O1s, and Cu2p corre-
sponding to the chemical composition of rGO/CuM30. The atomic per-
centages are 81.7, 14.49, 3.15, and 0.66 for C, O, N and Cu, respectively
with a Cu/N ratio = 0.21, confirming the formation of the Cu complex.
1
18 4
04–108°C, Color: Light brown. Mass percentage Calcd for C18H O :
1
H, 6.08; C, 72.47. Found (%): H, 6.49; C, 71.9. H NMR (400 MHz,
CDCl , δ, ppm): 7–7.80 (m, 8H, aromatic), 10.52 (s, 2H, CH-O), 2.1
t, 4H, C-CH -C), 4.2 (t, 4H, aliphatic O-CH -C) [26] (Fig. S1).
3
(
2
2
The C1s peak (Fig. 2b.) deconvoluted into four peaks: 291.2, 287.9,
3
2
85.0 and 284.2 eV are dedicated to (O=C-OH), (C=O), (C-C/C-H) sp
2
.5. Synthesis of Copper (II) macrocyclic Schiff base complex, CuM
2
and (C–C) sp respectively [30]. The N1s peak (Fig. 2c.) is deconvoluted
into bands at 406.2 and 399.9 eV attributed to N–O and C=N-C respec-
tively. The Cu2p peak (Fig. 2d.) shows 2p3/2 and 2p1/2 peaks at 934.4
Copper(II) macrocyclic Schiff base complex was synthesized accord-
ing to the literature [25] . Amount 3.00 g (10 mmol) of 1,4-bis(2-
formylphenoxy)butane and 2.42 g (10 mmol) of Cu(NO .3H O were
dissolved in 120 mL of CH OH. To the stirred solution, 10 mmol of
ethylenediamine (dissolved in 80 mL CH OH) was added dropwise
and stirred for 120 min. Finally, the obtained sample was filtrate and
washed with CH OH and dried at room temperature. Yield; 1.15 g
.H O. Anal. calcd for C20 30CuN 12: C 41.24, H
.15, N 9.62; found C 41.33, H 5.63, N 9.95. IR (in KBr, υ/cm ) 3300
and 953.7 eV with broad satellite peaks characteristic of Cu2+
.
)
3 2
2
Elemental mapping image (Fig. 3A) and EDAX spectrum (Fig. 3 B) of
rGO/CuM30 provide the distribution almost uniformly of the C, O, N and
Cu on the photocatalyst surface. This confirms that the Cu complexes
have been well crafted onto the rGO surface.
3
3
3
Fig. 4 shows FESEM images of as-synthesized GO, rGO and rGO/
CuM30, showing that the surface morphology is similar to sheets with
folds and wrinkles. These wrinkles can be attributed to the interaction
of oxygen groups in the sheets. SEM images show of rGO structure is
more compact than GO, which can be attributed to the decrease in the
number of oxygen groups in rGO. The FESEM images show that Cu com-
plex caused the surface of rGO to be compressed. This can be attributed
to a good combination between the Cu Complex and rGO. The uniform
distribution of Cu Complexes on reduced graphene oxide sheets indi-
cates that the rGO/CuM30 nanocomposite has been successfully formed.
Fig. 5 (A) shows the nitrogen adsorption and desorption on the
photocatalyst surface at different relative pressures. Due to the penetra-
tion of nitrogen in the capillary pores of the photocatalyst a type B (slits)
(
5
20%), [CuL](NO
3
)
2
2
H
4
O
−
1
−
(
H
2
O), 2954, 2887 (aliph-CH), 1626 (C=N), 1388, 1106 (NO
3
), 1240
(
Ar–O), 1160, 1042 ν(R-O), 526 (Cu–O), 480 (Cu–N).
2
.6. Preparation of photocatalyst
The rGO/CuMx composites were prepared using different amount of
CuL](NO .H O with rGO. In a typical synthesis of rGO/CuM30 (30% Cu
macrocyclic complex on rGO), 85.7 mg of as synthesis of [CuL](NO
O in 50 mL ethanol was added dropwise to the ultra-sonicated of
00 mg of rGO in 200 mL ethanol. The suspended mixture was stirred
for 12 h and centrifuged and washed with ethanol for several times
and dried at 70 °C for 12 h. For the preparation of catalysts with various
amount of CuMx (x = 5, 10, 20, 25, 40 and 50) amount 10.5, 22.2, 50,
[
)
3 2
2
3 2
) .
H
2
2
3
hysteresis is formed. Using the BET equation the pore volume (Cm /g),
6
6.7, 133.3 and 200 mg of [CuL](NO
rGO by the same method mentioned, respectively. For the synthesis of
Cu(II)/rGO, 35.6 mg of Cu(NO .3H O was dissolved in 30 mL of etha-
nol and added dropwise to the ultra-sonicated of 200 mg of rGO in
00 mL ethanol. The suspended mixture was stirred for 12 h and centri-
fuged and washed with ethanol for several times and dried at 70 °C for
2 h. For the synthesis of Schiff base ligand/rGO, 51 mg of Schiff base li-
3 2 2
) .H O was used with 200 mg of
)
3 2
2
2
1
gand was dissolved in 50 mL of ethanol and added dropwise to the
ultra-sonicated of 200 mg of rGO in 200 mL ethanol. The suspended
mixture was stirred for 12 h and centrifuged and washed with ethanol
for several times and dried at 70 °C for 12 h.
2.7. Photocatalytic reduction of nitroaromatic compounds
Catalytic activity tests were carried out by a LED lamp (Model No.
HP-FL-25 W-F-Hope LED Opto-Electric Co., Ltd. (Shenzhen, China)).
For this goal, 100 mg of rGO/CuMx was sonicated for 15 min in 10 mL
of 1:1:1 mixed solvent (CH
Then 1 mmol of nitrobenzene and 10 mmol of N
in mixture. Finally, the reactor of reaction was exposed under
3
OH/ dichloromethane/acetonitrile).
H.
O were added
2
4 2
H
Fig. 1. FT-IR spectra of (a) GO, (b) rGO, (c) rGO/CuM30 and (d) CuM.
3