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. 2023 Jun 8;9(6):471.
doi: 10.3390/gels9060471.

Construction of Pt@BiFeO3 Xerogel-Supported O-g-C3N4 Heterojunction System for Enhanced Visible-Light Activity towards Photocatalytic Degradation of Rhodamine B

Abubakar Usman Katsina  1   2 , Sonia Mihai  1 , Dănuţa Matei  1 , Diana-Luciana Cursaru  1 , Raluca Şomoghi  1   3 , Cristina Lavinia Nistor  3
Affiliations

Construction of Pt@BiFeO3 Xerogel-Supported O-g-C3N4 Heterojunction System for Enhanced Visible-Light Activity towards Photocatalytic Degradation of Rhodamine B

Abubakar Usman Katsina et al. Gels. .

Abstract

Synthetic organic pigments from the direct discharge of textile effluents are considered as colossal global concern and attract the attention of scholars. The efficient construction of heterojunction systems involving precious metal co-catalysis is an effective strategy for obtaining highly efficient photocatalytic materials. Herein, we report the construction of a Pt-doped BiFeO3/O-g-C3N4 (Pt@BFO/O-CN) S-scheme heterojunction system for photocatalytic degradation of aqueous rhodamine B (RhB) under visible-light irradiation. The photocatalytic performances of Pt@BFO/O-CN and BFO/O-CN composites and pristine BiFeO3 and O-g-C3N4 were compared, and the photocatalytic process of the Pt@BFO/O-CN system was optimized. The results exhibit that the S-scheme Pt@BFO/O-CN heterojunction has superior photocatalytic performance compared to its fellow catalysts, which is due to the asymmetric nature of the as-constructed heterojunction. The as-constructed Pt@BFO/O-CN heterojunction reveals high performance in photocatalytic degradation of RhB with a degradation efficiency of 100% achieved after 50 min of visible-light irradiation. The photodegradation fitted well with pseudo-first-order kinetics proceeding with a rate constant of 4.63 × 10-2 min-1. The radical trapping test reveals that h+ and •O2- take the leading role in the reaction, while the stability test reveals a 98% efficiency after the fourth cycle. As established from various interpretations, the considerably enhanced photocatalytic performance of the heterojunction system can be attributed to the promoted charge carrier separation and transfer of photoexcited carriers, as well as the strong photo-redox ability established. Hence, the S-scheme Pt@BFO/O-CN heterojunction is a good candidate in the treatment of industrial wastewater for the mineralization of organic micropollutants, which pose a grievous threat to the environment.

Keywords: S-scheme heterojunction photocatalyst; bismuth ferrite (BiFeO3); graphitic carbon nitride (g-C3N4); hydrothermal method; perovskites; photodegradation; rhodamine B; xerogels.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
XRD diffraction patterns of (a) O-CN, (b) BFO, (c) BFO25/O-CN75, (d) BFO50/O-CN50, (e) BFO75/O-CN25, (f) Pt@BFO50/O-CN50, (g) Pt@O-CN, and (h) Pt@BFO samples.
Figure 1
Figure 1
XRD diffraction patterns of (a) O-CN, (b) BFO, (c) BFO25/O-CN75, (d) BFO50/O-CN50, (e) BFO75/O-CN25, (f) Pt@BFO50/O-CN50, (g) Pt@O-CN, and (h) Pt@BFO samples.
Figure 2
Figure 2
FT-IR spectra of the samples.
Figure 3
Figure 3
SEM micrographs of (a) BFO, (b) O-CN, (c) BFO50/O-CN50, and (d) Pt@BFO50/O-CN50; (e) EDS mapping of Pt@BFO50/O-CN50.
Figure 4
Figure 4
Textural analysis of the as-prepared samples: (a) N2 physisorption isotherms; (b) BJH pore size distribution.
Figure 5
Figure 5
Absorbance data of RhB decomposition for 0.5 wt.% Pt@BFO50/O-CN50 at (a) 10 mg/L dye conc. and 50 mg catalyst dose, (b) 15 mg/L dye conc. and 30 mg catalyst dose, and (c) 15 mg/L dye conc. and 50 mg catalyst dose; (d) comparison of various catalysts; photocatalytic degradation of RhB in the presence of (e) 30 and 50 mg catalyst dose and (f) 10 mg/L initial conc. of RhB; pseudo-first-order kinetics of (g) 30 and 50 mg catalyst dose. (h) 10 mg/L initial conc. of RhB, and (i) 15 mg/L initial conc. of RhB.
Figure 5
Figure 5
Absorbance data of RhB decomposition for 0.5 wt.% Pt@BFO50/O-CN50 at (a) 10 mg/L dye conc. and 50 mg catalyst dose, (b) 15 mg/L dye conc. and 30 mg catalyst dose, and (c) 15 mg/L dye conc. and 50 mg catalyst dose; (d) comparison of various catalysts; photocatalytic degradation of RhB in the presence of (e) 30 and 50 mg catalyst dose and (f) 10 mg/L initial conc. of RhB; pseudo-first-order kinetics of (g) 30 and 50 mg catalyst dose. (h) 10 mg/L initial conc. of RhB, and (i) 15 mg/L initial conc. of RhB.
Figure 6
Figure 6
Effect of various trapping agents on free-radical species towards photodegradation of RhB.
Figure 7
Figure 7
Stability test of the as-constructed catalyst towards photodegradation of RhB.
Figure 8
Figure 8
FT-IR spectra of the as-constructed catalyst towards photodegradation of RhB before degradation test (a) and after degradation test cycle 4 (b).
Figure 9
Figure 9
UV-Vis DRS spectra and Tauc plots for (a) BFO, (b) Pt@BFO, (c) O-CN, (d) Pt@O-CN, (e) BFO25/O-CN75, (f) BFO50/O-CN50, (g) BFO75/O-CN25, and (h) Pt@BFO50/O-CN50 heterojunction.
Figure 9
Figure 9
UV-Vis DRS spectra and Tauc plots for (a) BFO, (b) Pt@BFO, (c) O-CN, (d) Pt@O-CN, (e) BFO25/O-CN75, (f) BFO50/O-CN50, (g) BFO75/O-CN25, and (h) Pt@BFO50/O-CN50 heterojunction.
Figure 10
Figure 10
Conventional separation and electron transfer mechanism for Pt@BFO50/O-CN50 heterojunction photocatalyst.
Figure 11
Figure 11
Proposed synergistic separation and electron transfer mechanism for S-scheme Pt@BFO50/O-CN50 heterojunction photocatalyst.
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