J. Mater. Sci. Technol. ›› 2018, Vol. 34 ›› Issue (9): 1511-1525.DOI: 10.1016/j.jmst.2017.12.020
• Orginal Article • Previous Articles Next Articles
Milad Jourshabania, Zahra Shariatiniaa*(), Alireza Badieibc
Received:
2017-10-24
Revised:
2017-11-26
Accepted:
2017-12-13
Online:
2018-09-20
Published:
2018-09-25
Contact:
Shariatinia Zahra
Milad Jourshabani, Zahra Shariatinia, Alireza Badiei. High efficiency visible-light-driven Fe2O3-xSx/S-doped g-C3N4 heterojunction photocatalysts: Direct Z-scheme mechanism[J]. J. Mater. Sci. Technol., 2018, 34(9): 1511-1525.
Independent factor | Unit | Level | ||||
---|---|---|---|---|---|---|
-α (-1.68) | -1 | 0 | +1 | -α (+1.68) | ||
A: Catalyst dosage | (g) | 0.04 | 0.06 | 0.1 | 0.12 | 0.14 |
B: Initial dye concentration | (mg L-1) | 3.27 | 6 | 10 | 14 | 16.73 |
C: Irradiation time | (min) | 79 | 120 | 150 | 180 | 280.9 |
Table 1 Actual and coded levels of independent factors.
Independent factor | Unit | Level | ||||
---|---|---|---|---|---|---|
-α (-1.68) | -1 | 0 | +1 | -α (+1.68) | ||
A: Catalyst dosage | (g) | 0.04 | 0.06 | 0.1 | 0.12 | 0.14 |
B: Initial dye concentration | (mg L-1) | 3.27 | 6 | 10 | 14 | 16.73 |
C: Irradiation time | (min) | 79 | 120 | 150 | 180 | 280.9 |
Fig. 3. (a) XPS survey spectrum of the Fe2O3(6.6)/CNS composite, (b) the expanded XPS spectrum in the C 1s, (c) N 1s, (d) S 2p, (e) Fe 2p and (f) O 1 s regions.
Region | Region percentage in composite (at.%) | Fitted peaks | Binding energy (eV) | Species | Species area (%) | Species percentage in composite (at.%) |
---|---|---|---|---|---|---|
O 1s | 5.76 | t1 | 530.0 | Fe-O in α-Fe2O3 | 5.5 | 0.31 |
t2 | 531.6 | O-H | 80.5 | 4.63 | ||
t3 | 533.0 | SO42- | 14.0 | 0.80 | ||
S 2p | 0.71 | u1 | 162.2 | S-Fe | 27.2 | 0.19 |
u2 | 163.9 | C-S-C | 24.9 | 0.17 | ||
u3 | 165.6 | FeIII-S (S-doped α-Fe2O3) | 6.3 | 0.04 | ||
u4 | 168.5 | SO42- | 41.6 | 0.29 | ||
Fe 2p | 0.37 | v1,v2 | 724.5, 710.9 | α-Fe2O3 | 65.2 | 0.24 |
v3 | 713.6 | Fe2(SO4)3 | 19.6 | 0.07 | ||
v4 | 717 | satellite of FeIII | 15.2 | 0.05 |
Table 2 Surface composition and positions of Fe 2p, O 1s, and S 2p XPS peaks for the Fe2O3(6.6)/CNS composite.
Region | Region percentage in composite (at.%) | Fitted peaks | Binding energy (eV) | Species | Species area (%) | Species percentage in composite (at.%) |
---|---|---|---|---|---|---|
O 1s | 5.76 | t1 | 530.0 | Fe-O in α-Fe2O3 | 5.5 | 0.31 |
t2 | 531.6 | O-H | 80.5 | 4.63 | ||
t3 | 533.0 | SO42- | 14.0 | 0.80 | ||
S 2p | 0.71 | u1 | 162.2 | S-Fe | 27.2 | 0.19 |
u2 | 163.9 | C-S-C | 24.9 | 0.17 | ||
u3 | 165.6 | FeIII-S (S-doped α-Fe2O3) | 6.3 | 0.04 | ||
u4 | 168.5 | SO42- | 41.6 | 0.29 | ||
Fe 2p | 0.37 | v1,v2 | 724.5, 710.9 | α-Fe2O3 | 65.2 | 0.24 |
v3 | 713.6 | Fe2(SO4)3 | 19.6 | 0.07 | ||
v4 | 717 | satellite of FeIII | 15.2 | 0.05 |
Fig. 4. TEM images of (a) CNS, (b) Fe2O3(6.6)/CNS composite. (c) Elemental mapping images of the C, N, S, O and Fe elements presenting in the Fe2O3(6.6)/CNS composite.
Sample | Fe2O3 content in composites (%) | S.Aa (m2/g) | P.Db (nm) | P.Vc (cm3/g) |
---|---|---|---|---|
Fe2O3 | - | 26.8 | 11.2 | 0.069 |
Fe2O3(2.3)/CNS | 2.3 | 17.5 | 23.4 | 0.089 |
Fe2O3(6.6)/CNS | 6.6 | 33.5 | 25.8 | 0.195 |
Fe2O3(7.2)/CNS | 7.2 | 25.1 | 23.1 | 0.090 |
CNS | - | 8.9 | 26.6 | 0.026 |
Table 3 Physicochemical and textural properties of synthesized materials.
Sample | Fe2O3 content in composites (%) | S.Aa (m2/g) | P.Db (nm) | P.Vc (cm3/g) |
---|---|---|---|---|
Fe2O3 | - | 26.8 | 11.2 | 0.069 |
Fe2O3(2.3)/CNS | 2.3 | 17.5 | 23.4 | 0.089 |
Fe2O3(6.6)/CNS | 6.6 | 33.5 | 25.8 | 0.195 |
Fe2O3(7.2)/CNS | 7.2 | 25.1 | 23.1 | 0.090 |
CNS | - | 8.9 | 26.6 | 0.026 |
Fig. 8. (a) Photocatalytic degradation of MB in aqueous solution using bulk g-C3N4, Fe2O3, CNS and Fe2O3/CNS nanocomposite photocatalysts having diverse Fe2O3 contents. (b) Time-dependent UV-vis absorption spectra for the MB photocatalytic degradation using the Fe2O3(6.6)/CNS catalyst. (c) Plots of ln(C0/C) versus reaction time for the MB photocatalytic degradation using various catalysts.
Run | A (g) | B (mg/L) | C (min) | Observed removal rate (%) | Predicted removal rate (%) |
---|---|---|---|---|---|
1 | 0.14 | 10.00 | 150.00 | 61.1 | 61.59 |
2 | 0.06 | 6.00 | 180.00 | 89.7 | 91.58 |
3 | 0.09 | 10.00 | 200.45 | 85.2 | 83.00 |
4 | 0.12 | 6.00 | 180.00 | 87.1 | 88.25 |
5 | 0.12 | 14.00 | 120.00 | 47.3 | 45.69 |
6 | 0.09 | 10.00 | 150.00 | 81.8 | 81.16 |
7 | 0.09 | 10.00 | 150.00 | 80.1 | 81.16 |
8 | 0.09 | 10.00 | 150.00 | 82.8 | 81.16 |
9 | 0.06 | 6.00 | 120.00 | 69.00 | 69.04 |
10 | 0.09 | 10.00 | 150.00 | 81.3 | 81.16 |
11 | 0.09 | 16.73 | 150.00 | 49.5 | 50.59 |
12 | 0.12 | 6.00 | 120.00 | 63.3 | 63.91 |
13 | 0.09 | 3.27 | 150.00 | 93.8 | 92.34 |
14 | 0.06 | 14.00 | 120.00 | 45.2 | 44.43 |
15 | 0.09 | 10.00 | 99.55 | 47.4 | 49.22 |
16 | 0.09 | 10.00 | 150.00 | 81.4 | 81.16 |
17 | 0.09 | 10.00 | 150.00 | 79.5 | 81.16 |
18 | 0.12 | 14.00 | 180.00 | 63.1 | 63.33 |
19 | 0.04 | 10.00 | 150.00 | 64.1 | 63.23 |
20 | 0.06 | 14.00 | 180.00 | 59.5 | 60.15 |
Table 4 Design experiment matrix based on CCD.
Run | A (g) | B (mg/L) | C (min) | Observed removal rate (%) | Predicted removal rate (%) |
---|---|---|---|---|---|
1 | 0.14 | 10.00 | 150.00 | 61.1 | 61.59 |
2 | 0.06 | 6.00 | 180.00 | 89.7 | 91.58 |
3 | 0.09 | 10.00 | 200.45 | 85.2 | 83.00 |
4 | 0.12 | 6.00 | 180.00 | 87.1 | 88.25 |
5 | 0.12 | 14.00 | 120.00 | 47.3 | 45.69 |
6 | 0.09 | 10.00 | 150.00 | 81.8 | 81.16 |
7 | 0.09 | 10.00 | 150.00 | 80.1 | 81.16 |
8 | 0.09 | 10.00 | 150.00 | 82.8 | 81.16 |
9 | 0.06 | 6.00 | 120.00 | 69.00 | 69.04 |
10 | 0.09 | 10.00 | 150.00 | 81.3 | 81.16 |
11 | 0.09 | 16.73 | 150.00 | 49.5 | 50.59 |
12 | 0.12 | 6.00 | 120.00 | 63.3 | 63.91 |
13 | 0.09 | 3.27 | 150.00 | 93.8 | 92.34 |
14 | 0.06 | 14.00 | 120.00 | 45.2 | 44.43 |
15 | 0.09 | 10.00 | 99.55 | 47.4 | 49.22 |
16 | 0.09 | 10.00 | 150.00 | 81.4 | 81.16 |
17 | 0.09 | 10.00 | 150.00 | 79.5 | 81.16 |
18 | 0.12 | 14.00 | 180.00 | 63.1 | 63.33 |
19 | 0.04 | 10.00 | 150.00 | 64.1 | 63.23 |
20 | 0.06 | 14.00 | 180.00 | 59.5 | 60.15 |
Fig. 9. Response surfaces and corresponding contour plots showing the interaction effects of the operating variables on the photocatalytic removal of MB using the Fe2O3(6.6)/CNS material. (a) Catalyst dosage and dye concentration, (b) irradiation time and catalyst dosage, (c) dye concentration and irradiation time.
Fig. 10. Effects of different trapping compounds on the MB photocatalytic degradation over the Fe2O3(6.6)/CNS composite photocatalyst under optimized conditions.
Fig. 11. Potential positions of CNS and Fe2O3 band edges and a schematic illustration of direct Z-scheme photocatalytic mechanism as well as type II heterojunction.
Catalyst | Pollutant (concentration) | Catalyst dose (g) | Light source | Irradiation time (min) | Activity (%) | Ref. |
---|---|---|---|---|---|---|
0.5%Fe3+/g-C3N4 | aRhB (10 mg/L) | 0.05 | 250 W, high-pressure sodium lamp | 120 | 100 | [ |
0.2%Fe2O3/g-C3N4 | RhB (10 mg/L) | 0.05 | 250 W, high-pressure sodium lamp | 120 | ~88 | [ |
2%α-Fe2O3/g-C3N4 | bDR 81 (5 × 10-5 M) | 0.075 | 100 W, tungsten-halogen lamp | 120 | ~75 | [ |
0.1%Fe2O3/g-C3N4 | RhB (20 mg/L) | 0.03 | 300 W, Xe lamp | 90 | ~85 | [ |
(0.08%Fe2O3/g-C3N4) + H2O2 | cMO (20 mg/L) | 0.05 | 1000 W, tungsten/halogen lamp (Philips) | 90 | ~88 | [ |
3%Ag/9%Fe3O4/g-C3N4 | Tetracycline (20 mg/L) | 0.05 | 300 W, Xe lamp (>420 nm) | 90 | 88 | [ |
Fe2O3(6.6)/CNS | dMB (8 mg/L) | 0.07 | 300 W, halogen lamp (λ > 400) | 150 | 82 | This study |
Table 5 Comparison of photodegradation performances of some catalysts used toward pollutant degradation in aqueous solution.
Catalyst | Pollutant (concentration) | Catalyst dose (g) | Light source | Irradiation time (min) | Activity (%) | Ref. |
---|---|---|---|---|---|---|
0.5%Fe3+/g-C3N4 | aRhB (10 mg/L) | 0.05 | 250 W, high-pressure sodium lamp | 120 | 100 | [ |
0.2%Fe2O3/g-C3N4 | RhB (10 mg/L) | 0.05 | 250 W, high-pressure sodium lamp | 120 | ~88 | [ |
2%α-Fe2O3/g-C3N4 | bDR 81 (5 × 10-5 M) | 0.075 | 100 W, tungsten-halogen lamp | 120 | ~75 | [ |
0.1%Fe2O3/g-C3N4 | RhB (20 mg/L) | 0.03 | 300 W, Xe lamp | 90 | ~85 | [ |
(0.08%Fe2O3/g-C3N4) + H2O2 | cMO (20 mg/L) | 0.05 | 1000 W, tungsten/halogen lamp (Philips) | 90 | ~88 | [ |
3%Ag/9%Fe3O4/g-C3N4 | Tetracycline (20 mg/L) | 0.05 | 300 W, Xe lamp (>420 nm) | 90 | 88 | [ |
Fe2O3(6.6)/CNS | dMB (8 mg/L) | 0.07 | 300 W, halogen lamp (λ > 400) | 150 | 82 | This study |
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