Synergy removal of Cr (VI) and organic pollutants over RP-MoS2/rGO photocatalyst

Bai, Xue; Du, Yonghua; Hu, Xiaoyun; He, Yudong; He, Chunliang; Liu, Enzhou

doi:10.1016/j.apcatb.2018.08.016

Cited by 181 publications

(60 citation statements)

References 54 publications

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“…The value of n depends on the type of electronic transition in the semiconductor ( n values of direct/indirect transition: 1/4). According to the previous reports, the n of Bi 2 WO 6 and MoS 2 is 1, and their E g are determined by the extrapolation of Tauc linear region [ 28 , 56 ]. The E g of pure Bi 2 WO 6 and MoS 2 are ~2.74 and 1.30 eV, respectively ( Figure 4 b,c), which are close to previously reported values [ 30 , 36 ].…”

Section: Resultsmentioning

confidence: 99%

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

Ren

Gong

et al. 2020

Nanomaterials

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Exploiting excellent photocatalytic activity and stable heterostructure composites are of critical importance for environmental sustainability. The spherical Bi2WO6/Bi2S3/MoS2 n-p heterojunction is first prepared via an in situ hydrothermal method using Bi2WO6, Na2MoO4·2H2O, and CH4N2S, in which the intermediate phase Bi2S3 is formed due to chemical coupling interaction of Bi2WO6 and CH4N2S. Scanning electron microscopy indicates that the compactness of the sample can be easily adjusted by changing the contents of S and Mo sources in the solution. The results of ultraviolet–visible (UV–vis) diffuse reflectance spectra, photoluminescence, transient photocurrent response, and electrochemical impedance spectra indicate that the formation of heterojunctions contributes to enhancing visible-light utilization and promoting photogenerated carrier separation and transfer. The composite material is used as a catalyst for the visible light photocatalytic reduction of Cr(VI). Remarkably, the optimal Bi2WO6/Bi2S3/MoS2 n-p heterojunction achieves the greatest Cr(VI) reduction rate of 100% within 75 min (λ > 420 nm, pH = 2); this rate is considerably better than the Cr(VI) reduction rate of pure Bi2WO6. The recycling experiment also reveals that the photocatalytic performance of the n-p heterojunction toward Cr(VI) is still maintained at 80% after three cycles, indicating that the n-p heterojunction has excellent structural stability. The capture experiment proves that the main active species in the system are electrons. The reasonable mechanism of Bi2WO6/Bi2S3/MoS2 photocatalytic reduction Cr(VI) is proposed. Our work provides new research ideas for the design of ternary heterojunction composites and new strategies for the development of photocatalysts for wastewater treatment.

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Section: Resultsmentioning

confidence: 99%

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

Ren

Gong

et al. 2020

Nanomaterials

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“…The simultaneous scavenging of coexisting pollutants has attracted lots of attention, because the pollutants widely coexist in wastewater, soil and air . Experiments on simultaneous photocatalytic degradation of MB and Cr(VI) on the WO 3 ‐CuS composite also were carried out herein to investigate the interaction effect.…”

Section: Resultsmentioning

confidence: 99%

One‐step synthesis of a WO₃‐CuS nanosheet heterojunction with enhanced photocatalytic performance for methylene blue degradation and Cr(VI) reduction

Liu

Zhang

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND: The photocatalytic activity of a pristine semiconductor is unsatisfactory due to the rapid recombination of photogenerated electrons and holes. Constructing composite photocatalysts has proven to be an effective method to suppress electron-hole recombination. The composites composed of two materials usually are synthesized through a two-step process. However, in this work, a simple one-step solvothermal method employing an homogeneous reaction system was adopted to synthesize a tungsten trioxide (WO 3 )-copper sulfide (CuS) nanosheet heterojunction with enhanced photocatalytic properties. RESULTS: The formation of the WO 3 -CuS heterojunction was confirmed by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray and X-ray photoelectron spectroscopy analysis. The composites showed improved visible light harvesting ability, and enhanced photoelectric and photocatalytic properties compared with pure WO 3 . The optimized composite displayed a photocurrent almost five-fold greater than the sum of the photocurrents of WO 3 and CuS, and had superior performance for methylene blue (MB) degradation and hexavalent chromium [Cr(VI)] reduction. The MB degradation and Cr(VI) reduction efficiencies were both improved when they co-existed in the photocatalytic system. Interferential ions Cl − and NO 3− were much less effective in the degradation of MB than in the reduction of Cr(VI). CONCLUSIONS: Improved photocatalytic activity was achieved after coupling CuS with WO 3 , due to the enhanced visible light absorption and efficient electron-hole separation. Photogenerated holes were found to be the dominant reactive species in the MB photodegradation process. A synergistic effect existed between MB degradation and Cr(VI) reduction. Interferential ions Cl − and NO 3 − had much greater effect on Cr(VI) reduction than MB degradation. Evaluation of the interference effects of ionsInorganic ions, such as chloride (Cl − ) and nitrate (NO 3 − ) ions, are found widely in natural water sources, and may interfere with the photocatalysis process. Ion interference experiments were conducted herein to investigate the photocatalytic activity of WO 3 -CuS in the presence of Cl − or NO 3 − ions. As shown in Fig. 10, Cl − and NO 3 − had little effect on MB degradation, whereas they J Chem Technol Biotechnol 2020; 95: 665-674

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“…The rGo acts as a charge suppressor and, due to its excellent electrical conductivity, it can trap the electron that is excited from the conduction band (CB) of SnO 2 and CeO 2 , allowing for longer photocatalyst activation. The exploitation of rGO, as an excellent charge separator and trapping site to sustain photocatalytic formation of ROS, was also explored by Bai et al, where a Red Phosporus (RP)-MoS 2 /rGO ternary photocatalyst was developed via a facile two-step hydrothermal [161]. RP and MoS 2 exhibited excellent photocatalytic activity and increased the number of excited electrons/holes under visible light irradiation, while rGO was responsible for enhancing charge separation to sustain and provide stability in electron recombination.…”

Section: Recent Progress and Performance Evaluationmentioning

confidence: 99%

The Roles of Nanomaterials in Conventional and Emerging Technologies for Heavy Metal Removal: A State-of-the-Art Review

et al. 2019

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Heavy metal (HM) pollution in waterways is a serious threat towards global water security, as high dosages of HM poisoning can significantly harm all living organisms. Researchers have developed promising methods to isolate, separate, or reduce these HMs from water bodies to overcome this. This includes techniques, such as adsorption, photocatalysis, and membrane removal. Nanomaterials play an integral role in all of these remediation techniques. Nanomaterials of different shapes have been atomically designed via various synthesis techniques, such as hydrothermal, wet chemical synthesis, and so on to develop unique nanomaterials with exceptional properties, including high surface area and porosity, modified surface charge, increment in active sites, enhanced photocatalytic efficiency, and improved HM removal selectivity. In this work, a comprehensive review on the role that nanomaterials play in removing HM from waterways. The unique characteristics of the nanomaterials, synthesis technique, and removal principles are presented. A detailed visualisation of HM removal performances and the mechanisms behind this improvement is also detailed. Finally, the future directions for the development of nanomaterials are highlighted.

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Synergy removal of Cr (VI) and organic pollutants over RP-MoS2/rGO photocatalyst

Cited by 181 publications

References 54 publications

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

One‐step synthesis of a WO₃‐CuS nanosheet heterojunction with enhanced photocatalytic performance for methylene blue degradation and Cr(VI) reduction

The Roles of Nanomaterials in Conventional and Emerging Technologies for Heavy Metal Removal: A State-of-the-Art Review

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Synergy removal of Cr (VI) and organic pollutants over RP-MoS2/rGO photocatalyst

Cited by 181 publications

References 54 publications

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

Spherical Bi2WO6/Bi2S3/MoS2 n-p Heterojunction with Excellent Visible-Light Photocatalytic Reduction Cr(VI) Activity

One‐step synthesis of a WO3‐CuS nanosheet heterojunction with enhanced photocatalytic performance for methylene blue degradation and Cr(VI) reduction

The Roles of Nanomaterials in Conventional and Emerging Technologies for Heavy Metal Removal: A State-of-the-Art Review

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One‐step synthesis of a WO₃‐CuS nanosheet heterojunction with enhanced photocatalytic performance for methylene blue degradation and Cr(VI) reduction