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Article

Multivalent Effect of Defect Engineered Ag2S/g-C3N4 3D Porous Floating Catalyst with Enhanced Contaminant Removal Efficiency

by
Nan Zhou
1,
Yanzhang Li
1,
Jie Chen
1,
Mingxin Song
1,* and
Linlin Zhang
2,*
1
School of Applied Science and Technology, Hainan University, Haikou 570228, China
2
Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, School of Ecology and Environment, Hainan University, Haikou 570228, China
*
Authors to whom correspondence should be addressed.
Int. J. Environ. Res. Public Health 2023, 20(2), 1357; https://doi.org/10.3390/ijerph20021357
Submission received: 22 November 2022 / Revised: 7 January 2023 / Accepted: 9 January 2023 / Published: 11 January 2023
(This article belongs to the Special Issue Advanced Treatment Technologies for Contaminants in Water)
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Abstract

:
Chlorophenols, as a major environmental pollutant, enter water systems through industrial wastewater, agricultural runoff and chemical spills, and they are stable, persistent under natural conditions, and highly hazardous to water resources. The objective of this article is to prepare Ag2S-modified C3N4 three-dimensional network photocatalyst by calcination method to use photocatalysis as an efficient, safe, and environmentally friendly method to degrade chlorophenols. Ag2S/C3N4 has an excellent visible light absorption range, low band gap, effective separation of photogenerated charges, and active free radicals production, all of which make for the enhancement of photocatalytic degradation performance of the Ag2S/C3N4 system. Under the light irradiation (λ ≥ 420 nm), the photocatalytic degradation efficiency of 2,4,6-Trichlorophenol reach 95% within 150 min, and the stable photocatalytic degradation activity can still be maintained under different pH water environment and four degradation cycles. When Ag2S is loaded on ACNs, more photogenerated electrons are generated and subsequent reactions produce highly reactive groups such as •O2− and •OH that will originally be able to continuously attack TCP molecules to degrade pollutants. Therefore, this study shows that the photocatalyst provides a novel research approach for realizing the application in the field of pollutant degradation.

1. Introduction

Environmental pollution is becoming increasingly serious and has become a global problem that plagues human development, especially water pollution [1,2,3]. Pollutants entering water systems through industrial wastewater, agricultural runoff and chemical spills have posed serious threats to plants and animals [4,5,6]. Among them, chlorophenols, as a major environmental pollutant, are stable under natural conditions and can exist in the environments for a long time, which has been classified as carcinogens by the United States Environmental Protection Agency (US-EPA) [7,8]. Chlorophenols is of particular concern to the environment due to its mutagenic and carcinogenic properties. Chlorinated phenols are widely distributed in the environment due to their use as intermediates in the synthesis of important pesticides and as pesticides themselves; the uncontrolled use and disposal of chlorophenols has had a serious impact on surface water quality. Chlorophenols is a chlorinated phenolic compound. Trichlorophenol has been detected in alarming concentrations in several rivers in different regions. It is also believed that Chlorophenols is produced as a by-product of industrial processes such as water disinfection. In some cases, uncontrolled plant effluent results in concentrations higher than the natural average [9,10,11]. Ramos-Ramírez [12] studies the structure of MgO-MgFe2O4 oxides with good photocatalytic degradation of Chlorophenols in aqueous solution and Ji [13] observed that the valence band holes (VB holes) of g-C3N4 play an important role in the degradation of chlorophenols under N2 gas environment and proposed a possible degradation pathway for Chlorophenols. Therefore, it is particularly significant to develop effective methods to remove these pollutants.
Photocatalysis is an efficient, safe, and environmentally friendly technology that has been used in CO2 reduction, H2O2 production, and organic pollutant degradation [14,15,16,17]. Several common photocatalysts, such as ZnO, TiO2, and C3N4, have appeared in environmental treatment [18,19,20,21]. C3N4 has been widely used due to its low preparation cost, controllable morphology, and excellent thermochemical stability [22,23,24,25]. However, the narrow light absorption range and the faster charge complexation problems seriously hinder its further wide application [26,27].
In recent years, different modification approaches have been developed to improve the charge separation problem of carbon nitride and enhance its photocatalytic activity, such as the preparation of different morphologies, the introduction of defect engineering, and the construction of heterogeneous structures [28,29,30,31]. Among them, compounding C3N4 with semiconductor materials to form heterojunction structures is an effective method for improving the photocatalytic activity of C3N4 [32,33,34,35,36,37,38,39,40]. Zhang et al. [41] compounded C3N4 with KOH, which slowed down the complexation rate of electron combination holes and greatly improved the generation of H2O2 under visible light irradiation. Li et al. [42] prepared P-C3N4/PS-C3N4 composites by a simple calcination approach to construct a well-matched band arrangement. This improves the efficient separation and transport of photogenerated electrons, and maintains the high oxidation of the holes and the excellent reduction performance of the electrons. Li et al. [43] prepared a 2D/2D C3N4/MoS2 heterojunction photocatalyst by the mechanical grinding method. The combination of MoS2 improved the concentration of photogenerated carriers and realized the effective separation of photogenerated carriers. And the hydrogen production efficiency can reach 385.04 μmol∙h−1∙g−1.
Ag2S, as a common silver-based material, has the advantages of simple preparation, excellent performance, and a narrow band gap, which is usually used as a cocatalyst to compound with other semiconductor materials [44,45]. Ag2S can be easily reduced to metal Ag under light, and Ag can be used as an electron trapping agent to contribute to the separation efficiency of photogenerated electrons, thus improving the photocatalytic activity of the system [46,47,48,49]. Di et al. [50] successfully prepared Ag2S/BiFeO3 Z-Scheme photocatalyst by co-precipitation method. Ag2S slowed down the compounding of electrons and holes in Ag2S/BiFeO3. Compared with Ag2S and BiFeO3, the degradation rate of methyl orange by Ag2S/BiFeO3 reached 97% after 4 h. Zhang et al. [51] deposited Ag2S nanoparticles on WO3 nanorods, which shortened the charge migration pathway without reducing the redox ability of the photogenerated electrons. Moreover, Ag2S/WO3 exhibited the H2 release efficiency of 32.9 μmol h−1, which was Roughly four times as high as Ag2S.
In this work, in order to use photocatalytic methods to degrade chlorophenols, which have long been difficult to degrade in natural water environments, three-dimensional Ag2S/C3N4 consisting of Ag2S and C3N4 in the uneven mass ratio were prepared by the calcination method. In addition, the crystal structure, chemical structure, and microstructure of Ag2S/C3N4 were studied. The construction of heterojunction promoted the quick separation of photogenerated electrons, and significantly improved the degradation performance of 2,4,6-trichlorophenol (TCP). It provides a novel strategy for C3N4 in the field of environmental pollution treatment.

2. Materials and Methods

2.1. Preparation of Ag2S

A certain quantity of thiourea was weighed and dissolved in deionized water. An appropriate amount of silver nitrate solution (S:Ag molar ratio is 1:2) was poured into a constant pressure droplet funnel and added to the above solution under magnetic stirring. The reaction solution was centrifuged, and washed with deionized water and anhydrous ethanol three times. The obtained solid was put in a vacuum oven at 60 °C and dried for 12 h. The dry, dark brown powder is Ag2S.

2.2. Preparation of C3N4

Referring to the preparation methods of C3N4 and complex made by Chen et al. [35] and Peng et al. [38], the preparation methods are designed as follows. A certain amount of cotton was completely immersed in a 15 g melamine solution, and the mixture was stirred magnetically for 1 h. Then the sample was freeze-dried to remove the solvent. The dried sample was heated in a nitrogen atmosphere of 550 °C for 2 h, and CN was obtained after cooling.

2.3. Preparation of Three-Dimensional Ag2S/C3N4 (ACNs)

As shown in Figure 1, there are detailed synthesis steps of three-dimensional Ag2S/C3N4 (ACNs). A certain amount of Ag2S powder was weighed and added to an appropriate amount of monocyanamide solution, and then ultrasonic was carried out to make Ag2S completely dispersed in the monocyanamide solution. An equal amount of cotton was added to the solution and continued to be ultrasounded until the solution was fully absorbed. Then the sample was freeze-dried for 24 h. The dried sample was put into a tubular furnace and calcined for 2 h at 550 °C under a nitrogen atmosphere to obtain three-dimensional Ag2S/C3N4 (ACNs). According to the different mass fractions of Ag2S, the different materials were named 10% wt% ACN, 30% wt% ACN, 50% wt% ACN, 70% wt% ACN, and 90% wt% ACN.

2.4. Characterization

X-ray diffraction (XRD) was obtained by a Bruker D8 Advance diffractometer (using Cu Kα radiation, λ = 1.54056 Å, 40 kV, 40 mA). The morphology and size of the resulting represented sample were investigated by using a field emission scanning electron microscopy (FE-SEM, Hitachi, Hitachi S-4800, Tokyo, Japan) and high-resolution transmission electron microscopy (HR-TEM, JEOL, JEM-2010, Tokyo, Japan). X-ray photoelectron spectroscopy was characterized by an X-ray photoelectron spectrometer (XPS, PHI-5700 ESCA, PHI, Chanhassen, MN, USA). The optical diffuse reflectance spectrum was conducted on a UV-vis-NIR scanning spectrophotometer (UV3600, Shimadzu, Kyoto, Japan) using an integrating sphere accessory.

2.5. Photocatalytic Degradation

Photocatalytic experiments were carried out by adding 50 mg of photocatalyst to 100 mL of a solution containing 2,4,6-trichlorophenol (TCP) (10 mg/L). Before the photocatalytic experiments, the solution containing the pollutants and the photocatalyst was placed in a dark room for 30 min to get the adsorption–desorption equilibrium. Then, the solution was irradiated under a 300 W xenon lamp. Every 20 min, 3 mL of each liquid sample was removed from the beaker and filtered with 0.22 μm Millipore filter heads for subsequent concentration tests [52,53].

3. Results and Discussion

3.1. Structure and Morphology of the ACNs

The crystal structure of ACNs was investigated by an X-ray diffractometer (XRD). Two types of carbon nitride were measured, and the results were presented As shown in Figure S1, there were two strong and sharp characteristic peaks at 13.01° and 27.22°, corresponding to the (100) and (002) crystal planes of C3N4 (JCPDS No. 87-1526). In Figure 2a, the diffraction peaks at 26.0°, 29.0°, 31.6°, 33.7°, 34.4°, 34.8°, 36.9°, 37.8°, and 40.8° were respectively assigned to (111), (111), (112), (120), (121), (022), (121), (103), and (031) crystal planes of monoclinic Ag2S (JCPDS 14-0072). For the ACNs, a diffraction peak was observed at 27.8°, which was the (002) crystal plane of g-C3N4. The characteristic peaks of Ag2S were observed at 31.6°, 33.7°, 34.4°, 34.8°, 36.6°, 36.9°, 37.2°, 37.8°, and 40.8°, and the diffraction peaks of Ag2S in ACNs gradually increased with the increase of Ag2S content. In addition, no additional impurity peaks were observed. The above results showed that ACNs with higher purity were successfully prepared.
To further analyze the chemical element composition and valence state of ACNs composites, 50% wt% ACN was taken as an example and analyzed by XPS. As shown in Figure 2b, 50% wt% ACN consisted of C, N, Ag, and S elements. In the C 1s spectrum (Figure 2c), the two characteristic peaks located at 284.8 eV and 288.1 eV corresponded to the C-C and sp2 hybrid carbon in n-C=N, respectively. In Figure 2d, the three characteristic peaks at 398.9 eV, 400.5 eV, and 401.7 eV corresponded to the C=N-C, N-(C)3, and C-N-H. In Figure 2e, two independent peaks situated at 367.8 eV and 373.8 eV were observed for Ag 3d5/2 and Ag 3d/2 in Ag2S. And the characteristic peaks at 162.2 eV and 163.4 eV in the S 2p spectrum ascribed to the S 2p3/2 and S 2p1/2 in Ag2S (Figure 2f). The above results indicated that ACNs composites have been successfully prepared.
The microstructures and morphology of ACNs were observed by SEM and TEM. As shown in Figure 3a,b, ACNs were a three-dimensional mesh material with a rough surface and porous structure. Ag2S was not completely wrapped on the surface, and C3N4 was still partially exposed. As for 50% wt% ACN and 70% wt% ACN, the content of Ag2S increases, but the three-dimensional structure of the ACNs material was still obvious, and no obvious aggregation of nanoparticles was observed on the surface (Figure 3c,d). When the mass fraction of Ag2S reached 90% wt%, the surface distribution of ACN was uneven and the agglomeration of large particles appeared obviously (Figure 3e). In addition, the TEM image of 50% wt% ACN showed that there were small sheets and holes on the surface (Figure 3f). The EDX mapping of 50% wt% ACN showed that it was composed of uniform distribution of C, N, Ag, and S elements.

3.2. Photocatalytic Removal of Pollutants

The TCP degradation experiment was conducted to assess the photocatalytic performance of the ACNs (λ ≥ 420 nm), and the changes in UV-Vis absorption spectra of TCP solutions were used to monitor the photocatalytic degradation process of TCP. All samples were treated in dark for 30 min to reach adsorption equilibrium. As shown in Figure 4a, the blank sample hardly degraded TCP under simulated sunlight irradiation. the degradation efficiency of ACNs composites was apparently higher than that of Ag2S and C3N4, and the photocatalytic activity of ACNs gradually increased with the increase of the mass fraction of Ag2S in ACNs. Among them, the 50% wt% ACN could achieve the most excellent photocatalytic degradation efficiency of 91.2%. When the mass fraction of Ag2S exceeded 50% wt%, the photocatalytic degradation rate of the ACNs gradually declined. This indicated the composites formed by the appropriate amount of Ag2S and C3N4 could effectively contribute to the separation and transmission performance of photogenerated charges. However, the excessive amount of Ag2S caused the three-dimensional structure of the ACNs to be covered, and a large amount of particle agglomeration occurred, which reduced the photocatalytic capacity of the ACNs. In Figure 4b the TCP degradation process of 50% wt% ACN was investigated under different pH water environments. It was clear that different degrees of TCP degradation of 50% wt% ACN occurred at different pH conditions, and it showed the best degradation performance at pH 5. Since TCP is a weakly acidic compound, it does not dissociate at acidic pH values below the pKa of TCP, and dispersive interactions prevail. The higher binding mode of halogenated organic compounds prevents repulsive interactions between the activated carbon surface and TCP molecules, increasing the electrostatic attraction between TCP molecules and adsorption sites. However, at alkaline pH, TCP dissociates as a weakly acidic electrolyte, and electrostatic repulsion occurs between the negative charge in the solution and the chlorophenolate anion. There may also be competition between OH ions and TCP ions, which may reduce the removal rate of TCP. In general, protonated phenolics dominate at low pH and are more readily adsorbed than ionized phenolics. Besides, cyclic degradation experiments of TCP were performed to evaluate the stability of ACNs composites. As shown in Figure 4c, the 50% wt% ACN still maintained high degradation activity against TCP after four cycles (82.5%), indicating that the 50% wt% ACN had excellent stability performance.
To determine the crucial reactive oxygen species generated in the TCP degradation of 50% wt% ACN under visible light irradiation (Figure 4d). The EDTA-2Na, BQ, and t-Butanol were used to capture h+, •O2−, and •OH, respectively. When EDTA-2Na was added, 50% wt% © could degrade 29.6% TCP within 60 min. The degradation efficiency was 21.1% with BQ added, indicating that h+ and •O2− played a key role in the TCP degradation of ACNs. Furthermore, with the addition of t-Butanol, 50% wt% © still degraded 79.5% TCP, showing that •OH was involved in the degradation process of TCP, but was not the main active substance.

3.3. Possible Photocatalytic Mechanism

ESR was utilized to clarify the reactive oxygen species produced by ACNs to reveal the photocatalytic mechanism (Figure 5a,b). Taking 50% wt% ACN as an example, the signals of •O2− and •OH were not tested under the dark, indicating that ACNs could not produce reactive oxygen species under this condition. Meanwhile, the characteristic peaks of DMPO-•OH and DMPO-•O2− were detected under visible light. These results indicated that the ACNs could generate •O2− and •OH under illumination. Combined with the live species capture experiment, the TCP degradation by ACNs was mainly dependent on •O2−, followed by h+, and the effect of •OH was minimal.
The separation and transport behavior of photogenerated carriers and the light absorption ability are inextricably linked to the photocatalytic performance of the ACNs, so ACNs were measured by UV-vis absorption spectra, band gap, and electrochemical impedance spectroscopy. As shown in Figure 6a, the ACNs exhibited excellent visible light absorption performance with the addition of Ag2S. According to the calculation, the band gap energies of 10% wt% ACN, 30% wt% ACN, 50% wt% ACN, 70% wt% ACN and 90% wt% ACN were 2.04 eV, 2.02 eV, 2.01 eV, 2.06 eV, and 2.18 eV, respectively (Figure 6b). Obviously, the band gap of 50% wt% ACN was the smallest. This may be because the introduction of Ag2S increased the light absorption capacity of the ACNs, thus reducing the band gap. In Figure 6c, the arc radius of 50% wt% ACN was smaller than that of other ACNs, showing the optimal charge separation performance. In conclusion, the 50% wt% ACN showed the best photocatalytic performance.
Based on the above experimental results, a possible photocatalytic degradation mechanism was presented. As shown in Figure 7, In 50% wt% ACN, visible light transferred electrons (e−) from the valence band (VB) of carbon nitride to the conduction band (CB), while an equal number of electron holes (h+) were retained in VB. Due to the difference in band gap between silver sulfide and carbon nitride before, the electrons and holes generated by carbon nitride were transferred to silver sulfide after the compounding of the two materials, which greatly inhibited the compounding of electrons and holes in the materials and improved the This greatly inhibits the complexation of electrons and holes and improves the utilization of visible light, which in turn improves the photocatalytic performance of the material and the degradation of small molecule organics. The generated electrons and holes are transferred at the interface of the composite coating, and the photogenerated electrons react with oxygen to form •O2−, which is the most effective way to improve the photocatalytic performance of the material [54,55,56,57].

4. Conclusions

In summary, the three-dimensional Ag2S/C3N4 composite photocatalysts were successfully prepared by a simple calcination method. The addition of Ag2S broadened the visible light response capacity of the ACNs, reduced the band gap, and promoted the effective separation of electrons and holes. Among the ACNs, the 50% wt% ACN exhibited excellent photocatalytic activity, which could degrade 91.2% TCP within 60 min and maintain good photocatalytic activity under different pH of the water environment. In addition, the high photocatalytic activity of 50% wt% ACN remained stable after four degradation cycles. In this process, •O2−, h+, and •OH all contributed to the improvement of photocatalytic degradation performance. This work provides a novel solution strategy for pollutant degradation.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/ijerph20021357/s1, Figure S1: The XRD patterns of C3N4; Figure S2: Mapping diagram of 50 wt% ACN; Figure S3: Corresponding pseudo-first-order kinetic curves of photocatalytic degradation of TCP, reaction rate constants of photocatalytic degradation of TCP; Figure S4: Photocatalytic degradation of TCP by adding 50% wt% ACN with different trapping agents.

Author Contributions

Conceptualization, Methodology, Investigation, Software, Writing—original draft, N.Z.; Conceptualization, Methodology, Investigation, Y.L.; Conceptualization, Methodology, Investigation, J.C.; Supervision, Funding acquisition, Resources, M.S.; Supervision, Data curation, Resources, L.Z. and M.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded in part by Hainan Provincial Natural Science Foundation of China (No. 622QN285, 620RC553, 521QN210), in part by Research initiation fund of Hainan University (No. KYQD(ZR)20062).

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy issues.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Gao, Q.; Xu, J.; Bu, X.-H. Recent advances about metal-organic frameworks in the removal of pollutants from wastewater. Coord Chem. Rev. 2019, 378, 17–31. [Google Scholar] [CrossRef]
  2. Ma, J.; Ma, Y.; Rong, X.; Song, Q.; Wu, B.; Lan, X.; Feng, Y.; Qiu, X.; Zhang, P. Persulfate-based controlled release beads for in situ chemical oxidation of common organic pollutants. J. Environ. Chem. Eng. 2021, 9, 105627. [Google Scholar] [CrossRef]
  3. Wazeer, I.; Hizaddin, H.F.; Hashim, M.A.; Hadj-Kali, M.K. An overview about the extraction of heavy metals and other critical pollutants from contaminated water via hydrophobic deep eutectic solvents. J. Environ. Chem. Eng. 2022, 10, 108574. [Google Scholar] [CrossRef]
  4. Dharupaneedi, S.P.; Nataraj, S.K.; Nadagouda, M.; Reddy, K.R.; Shukla, S.S.; Aminabhavi, T.M. Membrane-based separation of potential emerging pollutants. Sep. Purif. Technol. 2019, 210, 850–866. [Google Scholar] [CrossRef]
  5. Jiang, Y.; Zhao, H.; Liang, J.; Yue, L.; Li, T.; Luo, Y.; Liu, Q.; Lu, S.; Asiri, A.M.; Gong, Z.; et al. Anodic oxidation for the degradation of organic pollutants: Anode materials, operating conditions and mechanisms. A mini review. Electrochem. Commun. 2021, 123, 106912. [Google Scholar] [CrossRef]
  6. Chen, X.; Zhu, L.; Ma, Z.; Wang, M.; Zhao, R.; Zou, Y.; Fan, Y. Ag nanoparticles decorated ZnO nanorods as multifunctional SERS substrates for ultrasensitive detection and catalytic degradation of Rhodamine B. Nanomaterials 2022, 12, 2394. [Google Scholar] [CrossRef]
  7. Pei, S.; Wang, Y.; You, S.; Li, Z.; Ren, N. Electrochemical removal of chlorophenol pollutants by reactive electrode membranes: Scale-up strategy for engineered applications. Engineering 2022, 9, 77–84. [Google Scholar] [CrossRef]
  8. Acimovic, D.D.; Karic, S.D.; Nikolic, Z.M.; Brdaric, T.P.; Tasic, G.S.; Marceta Kaninski, M.P.; Nikolic, V.M. Electrochemical oxidation of the polycyclic aromatic hydrocarbons in polluted concrete of the residential buildings. Environ. Pollut. 2017, 220, 393–399. [Google Scholar] [CrossRef] [PubMed]
  9. Gao, J.; Liu, L.; Liu, X.; Zhou, H.; Huang, S.; Wang, Z. Levels and spatial distribution of chlorophenols-2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol in surface water of China. Chemosphere 2008, 71, 1181–1187. [Google Scholar] [CrossRef] [PubMed]
  10. Gaya, U.I.; Abdullah, A.H.; Hussein, M.Z.; Zainal, Z. Photocatalytic removal of 2,4,6-trichlorophenol from water exploiting commercial ZnO powder. Desalination 2010, 263, 176–182. [Google Scholar] [CrossRef]
  11. Xu, H.; Tong, N.; Huang, S.; Zhou, S.; Li, S.; Li, J.; Zhang, Y. Degradation of 2,4,6-trichlorophenol and determination of bacterial community structure by micro-electrical stimulation with or without external organic carbon source. Bioresour. Technol. 2018, 263, 266–272. [Google Scholar] [CrossRef] [PubMed]
  12. Ramos-Ramírez, E.; Tzompantzi-Morales, F.; Gutiérrez-Ortega, N.; Mojica-Calvillo, H.G.; Castillo-Rodríguez, J. Photocatalytic Degradation of 2,4,6-Trichlorophenol by MgO–MgFe2O4 Derived from Layered Double Hydroxide Structures. Catalysts 2019, 9, 454. [Google Scholar] [CrossRef] [Green Version]
  13. Ji, H.; Chang, F.; Hu, X.; Qin, W.; Shen, J. Photocatalytic degradation of 2,4,6-trichlorophenol over g-C3N4 under visible light irradiation. Chem. Eng. J. 2013, 218, 183–190. [Google Scholar] [CrossRef]
  14. Ezugwu, C.I.; Liu, S.; Li, C.; Zhuiykov, S.; Roy, S.; Verpoort, F. Engineering metal-organic frameworks for efficient photocatalytic conversion of CO2 into solar fuels. Coord. Chem. Rev. 2022, 450, 214245. [Google Scholar] [CrossRef]
  15. Qian, Y.; Zhang, F.; Pang, H. A review of MOFs and their composites-based photocatalysts: Synthesis and applications. Adv. Funct. Mater. 2021, 31, 2104231. [Google Scholar] [CrossRef]
  16. Feng, C.; Chen, Z.; Jing, J.; Hou, J. The photocatalytic phenol degradation mechanism of Ag-modified ZnO nanorods. J. Mater. Chem. C 2020, 8, 3000–3009. [Google Scholar] [CrossRef]
  17. Zheng, Y.; Chen, Y.; Gao, B.; Lin, B.; Wang, X. Phosphorene-based heterostructured photocatalysts. Engineering 2021, 7, 991–1001. [Google Scholar] [CrossRef]
  18. Kočí, K.; Reli, M.; Troppová, I.; Šihor, M.; Kupková, J.; Kustrowski, P.; Praus, P. Photocatalytic decomposition of N2O over TiO2/g-C3N4 photocatalysts heterojunction. Appl. Surf. Sci. 2017, 396, 1685–1695. [Google Scholar] [CrossRef]
  19. Deng, H.; Wang, X.-C.; Wang, L.; Li, Z.-J.; Liang, P.-L.; Ou, J.-Z.; Liu, K.; Yuan, L.-Y.; Jiang, Z.-Y.; Zheng, L.-R.; et al. Enhanced photocatalytic reduction of aqueous Re (VII) in ambient air by amorphous TiO2/g-C3N4 photocatalysts: Implications for Tc (VII) elimination. Chem. Eng. J. 2020, 401, 125977. [Google Scholar] [CrossRef]
  20. Vaiano, V.; Matarangolo, M.; Sacco, O.; Sannino, D. Photocatalytic treatment of aqueous solutions at high dye concentration using praseodymium-doped ZnO catalysts. Appl. Catal. B 2017, 209, 621–630. [Google Scholar] [CrossRef]
  21. Lim, J.; Kim, H.; Park, J.; Moon, G.H.; Vequizo, J.J.M.; Yamakata, A.; Lee, J.; Choi, W. How g-C3N4 works and is different from TiO2 as an environmental photocatalyst: Mechanistic view. Environ. Sci. Technol. 2020, 54, 497–506. [Google Scholar] [CrossRef] [PubMed]
  22. Zhang, M.; Yang, L.; Wang, Y.; Li, L.; Chen, S. High yield synthesis of homogeneous boron doping C3N4 nanocrystals with enhanced photocatalytic property. Appl. Surf. Sci. 2019, 489, 631–638. [Google Scholar] [CrossRef]
  23. Wang, L.; Tong, Y.; Feng, J.; Hou, J.; Li, J.; Hou, X.; Liang, J. G-C3N4-based films: A rising star for photoelectrochemical water splitting. Sustain. Mater. Technol. 2019, 19, e00089. [Google Scholar] [CrossRef]
  24. Kong, L.; Song, P.; Ma, F.; Sun, M. Graphitic carbon nitride-based 2D catalysts for green energy: Physical mechanism and applications. Mater. Today Energy 2020, 17, 100488. [Google Scholar] [CrossRef]
  25. Tong, H.; Ouyang, S.; Bi, Y.; Umezawa, N.; Oshikiri, M.; Ye, J. Nano-photocatalytic materials: Possibilities and challenges. Adv. Mater. 2012, 24, 229–251. [Google Scholar] [CrossRef] [PubMed]
  26. Yun, J.; Zhang, Y.; Ren, Y.; Kang, P.; Yan, J.; Zhao, W.; Zhang, Z.; Guo, H. Tunable type-I/type-II transition in g-C3N4/graphyne heterostructure by BN-doping: A promising photocatalyst. Sol. Energy Mater. Sol. Cells 2020, 210, 110516. [Google Scholar] [CrossRef]
  27. Lv, Z.; Cheng, X.; Liu, B.; Guo, Z.; Zhang, C. Py-COOH modified g-C3N4 nanosheets with enhanced visible-light photocatalytic H2 production. Appl. Surf. Sci. 2020, 504, 144486. [Google Scholar] [CrossRef]
  28. Lu, L.; Lv, Z.; Si, Y.; Liu, M.; Zhang, S. Recent progress on band and surface engineering of graphitic carbon nitride for artificial photosynthesis. Appl. Surf. Sci. 2018, 462, 693–712. [Google Scholar] [CrossRef]
  29. Liang, Q.; Li, Z.; Bai, Y.; Huang, Z.H.; Kang, F.; Yang, Q.H. A composite polymeric carbon nitride with in situ formed isotype heterojunctions for highly improved potocatalysis under visible light. Small 2017, 13, 1603182. [Google Scholar] [CrossRef]
  30. Song, T.; Hou, L.; Long, B.; Ali, A.; Deng, G.-J. Constructing ultralong hollow chain-ball-like carbon nitride implanted with oxygen for superior visible-light photocatalytic hydrogen production. J. Alloy. Compd. 2021, 857, 157609. [Google Scholar] [CrossRef]
  31. Hayat, A.; Sohail, M.; Taha, T.A.; Kumar Baburao Mane, S.; Al-Sehemi, A.G.; Al-Ghamdi, A.A.; Nawawi, W.I.; Palamanit, A.; Amin, M.A.; Fallatah, A.M.; et al. Synergetic effect of bismuth vanadate over copolymerized carbon nitride composites for highly efficient photocatalytic H2 and O2 generation. J. Colloid Interface Sci. 2022, 627, 621–629. [Google Scholar] [CrossRef] [PubMed]
  32. Adhikari, S.; Kim, D.-H. Heterojunction C3N4/MoO3 microcomposite for highly efficient photocatalytic oxidation of Rhodamine B. Appl. Surf. Sci. 2020, 511, 145595. [Google Scholar] [CrossRef]
  33. Rathi, V.; Panneerselvam, A.; Sathiyapriya, R. Graphitic carbon nitride (g-C3N4) decorated ZnWO4 heterojunctions architecture synthesis, characterization and photocatalytic activity evaluation. Diam. Relat. Mater. 2020, 108, 107981. [Google Scholar] [CrossRef]
  34. Guo, Z.; Ni, S.; Wu, H.; Wen, J.; Li, X.; Tang, T.; Li, M.; Liu, M. Designing nitrogen and phosphorus co-doped graphene quantum dots/g-C3N4 heterojunction composites to enhance visible and ultraviolet photocatalytic activity. Appl. Surf. Sci. 2021, 548, 149211. [Google Scholar] [CrossRef]
  35. Che, H.; Che, G.; Zhou, P.; Song, N.; Li, C.; Li, C.; Liu, C.; Liu, X.; Dong, H. Precursor-reforming strategy induced g-C3N4 microtubes with spatial anisotropic charge separation established by conquering hydrogen bond for enhanced photocatalytic H2-production performance. J. Colloid Interface Sci. 2019, 547, 224–233. [Google Scholar] [CrossRef]
  36. Chen, D.; Wei, L.; Wang, D.; Chen, Y.; Tian, Y.; Yan, S.; Mei, L.; Jiao, J. Ag2S/ZnO core-shell nanoheterojunction for a self-powered solid-state photodetector with wide spectral response. J. Alloy. Compd. 2018, 735, 2491–2496. [Google Scholar] [CrossRef]
  37. Feng, J.; Gao, M.; Zhang, Z.; Gu, M.; Wang, J.; Zeng, W.; Ren, Y. Comparing the photocatalytic properties of g-C3N4 treated by thermal decomposition, solvothermal and protonation. Results Phys. 2018, 11, 331–334. [Google Scholar] [CrossRef]
  38. Peng, D.; Wang, H.; Yu, K.; Chang, Y.; Ma, X.; Dong, S. Photochemical preparation of the ternary composite CdS/Au/g-C3N4 with enhanced visible light photocatalytic performance and its microstructure. RSC Adv. 2016, 6, 77760–77767. [Google Scholar] [CrossRef]
  39. Sierra, M.; Borges, E.; Esparza, P.; Mendez-Ramos, J.; Martin-Gil, J.; Martin-Ramos, P. Photocatalytic activities of coke carbon/g-C3N4 and Bi metal/Bi mixed oxides/g-C3N4 nanohybrids for the degradation of pollutants in wastewater. Sci. Technol. Adv. Mater. 2016, 17, 659–668. [Google Scholar] [CrossRef] [Green Version]
  40. Yang, Y.; Yin, C.; Li, K.; Tang, H.; Wang, Y.; Wu, Z. Cu Doped Crystalline Carbon-Conjugated g-C3N4, a Promising Oxygen Reduction Catalyst by Theoretical Study. J. Electrochem. Soc. 2019, 166, F755–F759. [Google Scholar] [CrossRef]
  41. Zhang, H.; Jia, L.; Wu, P.; Xu, R.; He, J.; Jiang, W. Improved H2O2 photogeneration by KOH-doped g-C3N4 under visible light irradiation due to synergistic effect of N defects and K modification. Appl. Surf. Sci. 2020, 527, 146584. [Google Scholar] [CrossRef]
  42. Li, J.; Qi, Y.; Mei, Y.; Ma, S.; Li, Q.; Xin, B.; Yao, T.; Wu, J. Construction of phosphorus-doped carbon nitride/phosphorus and sulfur co-doped carbon nitride isotype heterojunction and their enhanced photoactivity. J. Colloid Interface Sci. 2020, 566, 495–504. [Google Scholar] [CrossRef] [PubMed]
  43. Li, W.; Wang, L.; Zhang, Q.; Chen, Z.; Deng, X.; Feng, C.; Xu, L.; Sun, M. Fabrication of an ultrathin 2D/2D C3N4/MoS2 heterojunction photocatalyst with enhanced photocatalytic performance. J. Alloy. Compd. 2019, 808, 151681. [Google Scholar] [CrossRef]
  44. Dong, X.; Wang, S.; Wu, Q.; Liu, K.; Kong, F.; Liu, J. Co-catalyst boosted photocatalytic hydrogen production driven by visible-light over g-C3N4: The synergistic effect between Ag and Ag2S. J. Alloy. Compd. 2021, 875, 160032. [Google Scholar] [CrossRef]
  45. Yu, H.; Liu, W.; Wang, X.; Wang, F. Promoting the interfacial H2-evolution reaction of metallic Ag by Ag2S cocatalyst: A case study of TiO2/Ag-Ag2S photocatalyst. Appl. Catal. B 2018, 225, 415–423. [Google Scholar] [CrossRef]
  46. Nekooei, A.; Miroliaei, M.R.; Shahabi Nejad, M.; Sheibani, H. Enhanced visible-light photocatalytic activity of ZnS/S-graphene quantum dots reinforced with Ag2S nanoparticles. Mater. Sci. Eng. C 2022, 284, 115884. [Google Scholar] [CrossRef]
  47. Yuan, L.; Lu, S.W.; Yang, F.; Wang, Y.S.; Jia, Y.F.; Kadhim, M.S.; Yu, Y.M.; Zhang, Y.; Zhao, Y. A facile room-temperature synthesis of three-dimensional coral-like Ag2S nanostructure with enhanced photocatalytic activity. J. Mater. Sci. 2019, 54, 3174–3186. [Google Scholar] [CrossRef]
  48. Zhao, X.X.; Yang, H.; Li, R.S.; Cui, Z.M.; Liu, X.Q. Synthesis of heterojunction photocatalysts composed of Ag2S quantum dots combined with Bi4Ti3O12 nanosheets for the degradation of dyes. Environ. Sci. Pollut. Res. Int. 2019, 26, 5524–5538. [Google Scholar] [CrossRef]
  49. Barrocas, B.; Entradas, T.J.; Nunes, C.D.; Monteiro, O.C. Titanate nanofibers sensitized with ZnS and Ag2S nanoparticles as novel photocatalysts for phenol removal. Appl. Catal. B Environ. 2017, 218, 709–720. [Google Scholar] [CrossRef]
  50. Di, L.; Yang, H.; Xian, T.; Liu, X.; Chen, X. Photocatalytic and photo-fenton catalytic degradation activities of Z-Scheme Ag2S/BiFeO3 heterojunction composites under visible-light irradiation. Nanomaterials 2019, 9, 399. [Google Scholar] [CrossRef]
  51. Zhang, S.; Wang, J.; Chen, S.; Li, R.; Peng, T. Construction of Ag2S/WO3 direct Z-Scheme photocatalyst for enhanced charge separation efficiency and H2 generation activity. Ind. Eng. Chem. Res. 2019, 58, 14802–14813. [Google Scholar] [CrossRef]
  52. Gao, Y.; Duan, J.; Zhai, X.; Guan, F.; Wang, X.; Zhang, J.; Hou, B. Photocatalytic Degradation and Antibacterial Properties of Fe3+-Doped Alkalized Carbon Nitride. Nanomaterials 2020, 10, 1751. [Google Scholar] [CrossRef] [PubMed]
  53. Gaigneaux, E.M.; Devillers, M.; DeVos, D.E.; Hermans, S.; Jacobs, P.A.; Martens, J.A.; Ruiz, P. Scientific, Bases for the Preparation of Heterogeneous Catalysts; Elsevier: Amsterdam, The Netherlands, 2006; Volume 162, pp. 1–1048. [Google Scholar]
  54. Zhao, S.; Wu, J.; Xu, Y.; Zhang, X.; Han, Y.; Xing, H. CdS/Ag2S/g-C3N4 ternary composites with superior photocatalytic performance for hydrogen evolution under visible light irradiation. Dalton Trans. 2021, 50, 3253–3260. [Google Scholar] [CrossRef] [PubMed]
  55. Dong, S.; Zeng, Z.; Cai, W.; Zhou, Z.; Dou, C.; Liu, H.; Xia, J. The zeta potentials of g-C3N4 nanoparticles: Effect of electrolyte, ionic strength, pH, and humic acid. J. Nanoparticle Res. 2019, 21, 233. [Google Scholar] [CrossRef]
  56. Xue, J.; Ma, T.; Shen, Q.; Guan, R.; Jia, H.; Liu, X.; Xu, B. A novel synthesis method for Ag/g-C3N4 nanocomposite and mechanism of enhanced visible-light photocatalytic activity. J. Mater. Sci. Mater. Electron. 2019, 30, 15636–15645. [Google Scholar] [CrossRef]
  57. Xue, B.; Jiang, H.-Y.; Sun, T.; Mao, F.; Ma, C.-C.; Wu, J.-K. Microwave-assisted one-step rapid synthesis of ternary Ag/Ag2S/g-C3N4 heterojunction photocatalysts for improved visible-light induced photodegradation of organic pollutant. J. Photochem. Photobiol. A Chem. 2018, 353, 557–563. [Google Scholar] [CrossRef]
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Figure 1. Schematic illustration of the preparation of ACNs.
Figure 1. Schematic illustration of the preparation of ACNs.
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Figure 2. (a) The XRD patterns of Ag2S and ACNs. XPS spectra of 50% wt% ACN: (b) survey, (c) C 1s, (d) N 1s, (e) Ag 3d and (f) S 2p.
Figure 2. (a) The XRD patterns of Ag2S and ACNs. XPS spectra of 50% wt% ACN: (b) survey, (c) C 1s, (d) N 1s, (e) Ag 3d and (f) S 2p.
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Figure 3. SEM images of (a) 10% wt% ACN, (b) 30% wt% ACN, (c) 50% wt% ACN, (d) 70% wt% ACN and (e) 90% wt% ACN, (f) TEM image of 50% wt% ACN.
Figure 3. SEM images of (a) 10% wt% ACN, (b) 30% wt% ACN, (c) 50% wt% ACN, (d) 70% wt% ACN and (e) 90% wt% ACN, (f) TEM image of 50% wt% ACN.
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Figure 4. (a) Photocatalytic degradation of TCP under simulated sunlight irradiation. (b) Photocatalytic degradation of TCP in different waters under simulated sunlight irradiation. (c) Degradation rate and stability. (d) Photocatalytic degradation efficiency of TCP for 50% wt% ACNs with different quenchers.
Figure 4. (a) Photocatalytic degradation of TCP under simulated sunlight irradiation. (b) Photocatalytic degradation of TCP in different waters under simulated sunlight irradiation. (c) Degradation rate and stability. (d) Photocatalytic degradation efficiency of TCP for 50% wt% ACNs with different quenchers.
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Figure 5. ESR spectra under dark and visible-light irradiation: (a) DMPO-•O2− of 50% wt% ACNs, (b) DMPO-•OH of 50% wt% ACNs.
Figure 5. ESR spectra under dark and visible-light irradiation: (a) DMPO-•O2− of 50% wt% ACNs, (b) DMPO-•OH of 50% wt% ACNs.
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Figure 6. (a) UV-vis absorption spectra of ACNs. (b) Plots of the (ahγ)2 versus photon energy (hγ) of ACNs. (c) Electrochemical impedance spectroscopy of ACNs.
Figure 6. (a) UV-vis absorption spectra of ACNs. (b) Plots of the (ahγ)2 versus photon energy (hγ) of ACNs. (c) Electrochemical impedance spectroscopy of ACNs.
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Figure 7. Schematic diagram of ACNs for degradation of pollutants.
Figure 7. Schematic diagram of ACNs for degradation of pollutants.
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Zhou, N.; Li, Y.; Chen, J.; Song, M.; Zhang, L. Multivalent Effect of Defect Engineered Ag2S/g-C3N4 3D Porous Floating Catalyst with Enhanced Contaminant Removal Efficiency. Int. J. Environ. Res. Public Health 2023, 20, 1357. https://doi.org/10.3390/ijerph20021357

AMA Style

Zhou N, Li Y, Chen J, Song M, Zhang L. Multivalent Effect of Defect Engineered Ag2S/g-C3N4 3D Porous Floating Catalyst with Enhanced Contaminant Removal Efficiency. International Journal of Environmental Research and Public Health. 2023; 20(2):1357. https://doi.org/10.3390/ijerph20021357

Chicago/Turabian Style

Zhou, Nan, Yanzhang Li, Jie Chen, Mingxin Song, and Linlin Zhang. 2023. "Multivalent Effect of Defect Engineered Ag2S/g-C3N4 3D Porous Floating Catalyst with Enhanced Contaminant Removal Efficiency" International Journal of Environmental Research and Public Health 20, no. 2: 1357. https://doi.org/10.3390/ijerph20021357

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