ZnS–CdS/Graphene oxide heterostructures prepared by a light irradiation-assisted method for effective photocatalytic hydrogen generation

Wang, Xuewen; Yuan, Biao; Xie, Zihan; Wang, Dongxue; Zhang, Rongbin

doi:10.1016/j.jcis.2015.01.051

Cited by 34 publications

(11 citation statements)

References 43 publications

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“…In the case of S9 , the complete conversion of nitrobenzene to aniline occurs within the time span of 4 h, whereas in the case of solid solutions S1 , S3 , and S5 , the complete conversion of nitrobenzene to aniline occurs in the time span of 22, 13, and 6 h, respectively (Table ). The activity of S9 was found to be much higher than those of pure ZnS and CdS which is in accordance with the higher water splitting activity of the solid solution over individual metal sulfides as explained before. − Furthermore, the heterogeneity of photocatalyst S9 was examined to understand whether the reaction occurred on the photocatalyst or was catalyzed by the species leached from the catalyst into solution. To study this, a separate reaction was carried out in which the photocatalyst S9 was removed after 2 h of irradiation, and the conversion of nitrobenzene was found to be 58%.…”

Section: Resultssupporting

confidence: 80%

Template-Free Synthesis of Zn_1–xCd_xS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Kaur

Nagaraja

2017

ACS Sustainable Chem. Eng.

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A facile, one-pot, solvothermal synthesis of nanocrystals (NCs) of Zn1–x Cd x S (x = 0.1 (S1)–0.9 (S9)) solid solutions has been successfully carried out using 4,4′-dipyridyldisulfide (DPDS = (C5H4N)2S2)) as a new temperature-dependent in situ source of S2– ions. Powder XRD patterns of the samples revealed gradual phase transformation from cubic to hexagonal upon increasing the Cd content (x) in the solid solutions Zn1–x Cd x S (0 ≤ x ≤ 1). FESEM analyses showed almost spherical morphology of the solid solutions, S2, S5, and S9. HR-TEM analyses of S3 and S9 unveiled the presence of small nanocrystals (NCs) of size 7 and 15 nm, respectively, and highlights the discontinuity in the pattern of lattice fringes. Optical measurements revealed that Zn1–x Cd x S solid solutions exhibit precisely tunable band structure with varying the concentration of Cd content. Furthermore, visible-light-assisted photocatalytic investigation revealed very good activity of the Zn0.7Cd0.3S solid solution for water splitting with H2 generation rate of 750 μmol h–1 g–1. Interestingly, for the first time, the water splitting activity of the Zn1–x Cd x S NCs has been applied for efficient reduction of nitroaromatic pollutants in water by utilizing water as a source of hydrogen. Remarkably, various substituted nitroaromatics containing both electron-donating and -withdrawing groups as well as dinitroaromatics can be efficiently reduced to their corresponding amines in high yield and selectivity. Also, the photocatalyst can be recycled and reused for several cycles without significant loss of the activity. The plausible mechanism for the reduction of nitroaromatics in water by Zn1–x Cd x S solid solution has also been studied. Herein we demonstrate a unique approach wherein water acts as a source of reducing agent for the visible-light-assisted photocatalytic reduction of nitroaromatic pollutants in water by Zn1–x Cd x S solid solutions.

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Section: Resultssupporting

confidence: 80%

Template-Free Synthesis of Zn_1–xCd_xS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Kaur

Nagaraja

2017

ACS Sustainable Chem. Eng.

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“…The association of ZnS-CdS with GO to form the ZnS-CdS/GO heterostructure for the photocatalytic H 2 gas generation result in the duplication of the recorded production rate. Moreover, doping ZnS-CdS/GO heterostructure with 2 wt% Pt nanoparticles to serve as co-catalysts, the hydrogen generation rate is significantly elevated to 1.68 and 0.78 mmol h −1 upon irradiation with UV-visible or visible light, respectively [28].…”

Section: Non-oxidic Binary Compoundsmentioning

confidence: 99%

“…GO can act as a common platform for more than one active site to produce enhanced heterostructure for photocatalytic activity. For example, ZnS-CdS/GO shows a twice activity toward photocatalytic hydrogen generation compared with ZnS-CdS standalone heterostructures [28]. Graphene Oxide -Applications and Opportunities…”

Section: Coupling Multiple Active Sitesmentioning

confidence: 99%

Immobilization Impact of Photocatalysts onto Graphene Oxide

Gemeay¹,

El-Halwagy²

2018

Graphene Oxide - Applications and Opportunities

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The densely functionalized graphene oxide (GO) surface and the two-dimensional carbon structure had provided a unique opportunity for supporting photocatalysts. Concerning GO-based photocatalysis, GO plays the role of an electron acceptor that accelerates the interfacial electron-transfer process, recombination retardant of charge carriers, finetuner for the electronic and chemical properties of the supported photocatalysts, and finally, a carrier transport between different active sites. Moreover, standalone GO is a p-doped semiconductor material with the π* orbital of the oxygen remains as the conduction band minimum (CBM) while the valance band maximum (VBM) changes gradually from the p-orbital of carbon to the 2p orbital of oxygen upon oxidation. The outstanding features of the GO-based photocatalysis opened the way to serve the progress in many environmental applications including water treatment, air purification, water splitting, CO 2 conversion, and sensing applications.

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“…CdS is known to be an efficient photocatalyst for the generation of hydrogen; however, its use often suffers from the quick recombination of photogenerated charge carriers . Cation doping into CdS, that is, solid‐solution Zn x Cd 1– x S, prevents the recombination of photoinduced holes and electrons due to the formation of an electrostatic field in the crystalline lattice .…”

Section: Introductionmentioning

confidence: 99%

Solid‐Solution Coordination Polymers as Precursors for Zn_xCd_1–xS/C Composite Nanowires

et al. 2017

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The development of synthetic routes to nanomaterials has been motivated by their potential applications in electronics, optics, and catalytic reactions. Solution‐based synthesis has relied on organic stabilizers to regulate the crystal growth. Despite the beneficial effect on crystal growth, organic stabilizers attached to the resulting particles reduce the accessibility of reactants and inhibit charge transport, resulting in a lower catalytic activity than expected. In this work we have demonstrated that coordination polymers (CPs) can be used as precursors for photocatalysts without stabilizers. The pyrolysis of CP nanowires of [Cd(l‐cysteinate)]n gave CdS/C nanowires (CdS/C‐NWs) that exhibit photocatalytic activity for hydrogen generation superior to CdS nanowires with organic stabilizers (CdS/stb‐NWs). Transient absorption spectroscopy showed that CdS/C‐NWs provide an active surfaces to facilitate catalytic reactions associated with electron migration. Moreover, Zn‐doped CdS nanowires (ZnxCd1‐xS/C‐NWs) obtained by the pyrolysis of CPs exhibited higher photocatalytic activity than nondoped CdS/C‐NWs. The improvement in photocatalytic activity is attributable to the prolonged lifetime of photoexcited electrons. The pyrolysis of CPs provides a facile means to design nanocomposites that realize efficient catalytic reactions associated with facile charge transfer.

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ZnS–CdS/Graphene oxide heterostructures prepared by a light irradiation-assisted method for effective photocatalytic hydrogen generation

Cited by 34 publications

References 43 publications

Template-Free Synthesis of Zn_1–xCd_xS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Template-Free Synthesis of Zn_1–xCd_xS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Immobilization Impact of Photocatalysts onto Graphene Oxide

Solid‐Solution Coordination Polymers as Precursors for Zn_xCd_1–xS/C Composite Nanowires

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ZnS–CdS/Graphene oxide heterostructures prepared by a light irradiation-assisted method for effective photocatalytic hydrogen generation

Cited by 34 publications

References 43 publications

Template-Free Synthesis of Zn1–xCdxS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Template-Free Synthesis of Zn1–xCdxS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Immobilization Impact of Photocatalysts onto Graphene Oxide

Solid‐Solution Coordination Polymers as Precursors for ZnxCd1–xS/C Composite Nanowires

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Template-Free Synthesis of Zn_1–xCd_xS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Template-Free Synthesis of Zn_1–xCd_xS Nanocrystals with Tunable Band Structure for Efficient Water Splitting and Reduction of Nitroaromatics in Water

Solid‐Solution Coordination Polymers as Precursors for Zn_xCd_1–xS/C Composite Nanowires