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. 2023 Mar 21;8(13):11824-11836.
doi: 10.1021/acsomega.2c06678. eCollection 2023 Apr 4.

One-Step Fabrication of the ZnO/g-C3N4 Composite for Visible Light-Responsive Photocatalytic Degradation of Bisphenol E in Aqueous Solution

Mahmudul Hassan Suhag  1   2 , Aklima Khatun  1 , Ikki Tateishi  3 , Mai Furukawa  1 , Hideyuki Katsumata  1 , Satoshi Kaneco  1
Affiliations

One-Step Fabrication of the ZnO/g-C3N4 Composite for Visible Light-Responsive Photocatalytic Degradation of Bisphenol E in Aqueous Solution

Mahmudul Hassan Suhag et al. ACS Omega. .

Abstract

The ZnO/g-C3N4 composite was successfully synthesized by a simple one-step calcination of a urea and zinc acetate mixture. The photocatalytic activity of the synthesized composite was evaluated in the degradation of bisphenol E (BPE). The morphology, crystallinity, optical properties, and composition of the synthesized composite were characterized by using various analytical techniques such as scanning electron microscopy (SEM), transmitted electron microscopy (TEM), field emission-electron probe microanalysis (FE-EPMA), nitrogen adsorption and desorption isotherm measurement, Fourier-transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The degradation rate of BPE with the ZnO/g-C3N4 composite was 8 times larger than that obtained with pure g-C3N4 at the optimal conditions. The excellent photocatalytic activity was attributed to the synergistic effect between the g-C3N4 and ZnO, which enhanced the efficiency of charge separations, reduced the e-/h+ pairs recombination, and increased the visible light absorption ability. The radical scavenger studies indicated that the •O2 - and h+ species were mainly responsible for the degradation of BPE. The stability test suggested the chemical and photostability of the synthesized composite. Two possible photocatalytical mechanisms have been suggested.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
TG analysis curve of the ZnO/g-C3N4 composite.
Figure 2
Figure 2
FTIR spectra of ZnO, g-C3N4, the ZnO/g-C3N4 composite, and the ZnO/g-C3N4 composite after the degradation reaction.
Figure 3
Figure 3
(a) Survey XPS spectra of g-C3N4 and the ZnO/g-C3N4 composite; overlapping high-resolution XPS (b) C 1s, (c) N 1s, and (d) O 1s spectra of g-C3N4 and the ZnO/g-C3N4 composite and (e) high-resolution XPS Zn 2p spectra of the ZnO/g-C3N4 composite.
Figure 4
Figure 4
SEM images of (a) ZnO, (b) g-C3N4, (c) the ZnO/g-C3N4 composite, and (d) the ZnO/g-C3N4 composite after the degradation reaction; and TEM images of (e) ZnO, (f) g-C3N4, (g) the ZnO/g-C3N4 composite, and (h) the ZnO/g-C3N4 composite after the degradation reaction.
Figure 5
Figure 5
(a) Kubelka-Munk function of UV–vis DRS and (b) PL spectra (upon the excitation at 260 nm wavelength) of the prepared ZnO, g-C3N4, and the ZnO/g-C3N4 composite after the degradation reaction; and (c) EIS Nyquist plots of g-C3N4 and ZnO/g-C3N4.
Figure 6
Figure 6
(a) Photocatalytic degradation of BPE with different catalysts under visible light irradiation and (b) the plot of −ln(C/C0) versus irradiation time; BPE: 3 ppm (30 mL), photocatalyst: 30 mg.
Figure 7
Figure 7
(a) Effect of scavenger role on the photocatalytic degradation of BPE with the ZnO/g-C3N4 composite and (b) plot of −ln(C/C0) versus irradiation time; BPE: 3 ppm (30 mL), photocatalyst: 30 mg.
Figure 8
Figure 8
(a) Conventional charge transfer mechanism and (b) IFCT mechanism for photocatalytic degradation of BPE with the ZnO/g-C3N4 composite.
See this image and copyright information in PMC

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