Photocatalytic Cr(VI) reduction in metal-organic frameworks: A mini-review

Wang, Chong-Chen; Du, Xuedong; Li, Jin; Guo, Xin-Xing; Wang, Peng; Zhang, Jia

doi:10.1016/j.apcatb.2016.04.030

Cited by 560 publications

(140 citation statements)

References 178 publications

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“…Also, the oxide and hydroxide forms of Cr(III) was precipitated as Cr(OH) 3 under ZnO surface due tothe negligible Cr(III) observed over the experiments [91,92]. It was expected increase in the Cr(III) concentrations in the same acidic pH.…”

Section: Photocatalytic Reduction Of Cr(vi)mentioning

confidence: 93%

The interplay between morphology and photocatalytic activity in ZnO and N-doped ZnO crystals

et al. 2017

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Photocatalytic materials can perform oxidative and reductive reactions over their surfaces when excited with light. Intrinsic characteristics of the material such as superficial area, morphological structure, and crystalline phase exposition play a fundamental role in the corresponding reaction paths. However, especially in doped semiconductors, as ZnO:N, less is known about how the synthesis parameters affect the morphologies and the photocatalytic activity simultaneously. To solve this issue, ZnO and ZnO:N samples were obtained using microwave-assisted hydrothermal and modified polymeric precursor methods of synthesis. Samples morphologies were characterized by TEM and FE-SEM. Crystallographic phases were observed by XRD and optical characteristics by DRS. XPS results confirmed the doping process. Degradation of Rhodamine-B and Cr(VI) reduction were employed as probe reactions to investigate their photocatalytic activity. Although the crystallographic structure of these powders maintains the ZnO hexagonal wurtzite structure, the optical properties and morphologies, and photocatalytic activities present different behaviors. Also, density functional theory calculations were employed to determine the specific features related to electronic structure, morphology, and photocatalytic activity.Different synthesis methods produce a singular behavior in the physicochemical properties of materials, and the doping effect produces various modifications in RhB degradation and Cr(VI) reduction for each synthesis method. Crystal face exposition and morphologies are related to the improvement in the photocatalytic activity of the materials.

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Section: Photocatalytic Reduction Of Cr(vi)mentioning

confidence: 93%

The interplay between morphology and photocatalytic activity in ZnO and N-doped ZnO crystals

et al. 2017

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“…Owing to different redox potentials of Cr2O7 2− under different pH conditions [43], effects of pH values on photoactivity of MoS2/TiO2 heterojunction system for reducing of Cr(VI) were investigated ( Figure 8). It was observed that the adsorption ability of MoS2/TiO2 composite for Cr(VI) under acid condition is the similar as under neutral and base condition during dark equilibrium process.…”

Section: Photocatalytic Activity Of Mos2/tio2 Nbs Heterojunctionsmentioning

confidence: 99%

Synergically Improving Light Harvesting and Charge Transportation of TiO2 Nanobelts by Deposition of MoS2 for Enhanced Photocatalytic Removal of Cr(VI)

Liu

et al. 2017

Catalysts

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Herein, MoS 2 /TiO 2 nanobelts heterojunction have been successfully synthesized by in situ growth method for photocatalytic reduction of Cr(VI). TiO 2 nanobelts (NBs) with rough surface were prepared firstly by acidic treatment process, which is beneficial for deposition and growth of MoS 2 to form heterojunctions. As a result of special energy level offset and nanostructure, MoS 2 /TiO 2 NBs composite were endowed with higher light-harvesting capacity and charge transportation efficiency, which are indispensible merits for excellent photocatalytic activity. The photocatalytic reduction of Cr(VI) reveals that the synthesized MoS 2 /TiO 2 NBs composite have superior photocatalytic ability than other samples. Meanwhile, a photoreduction mechanism is proposed based on the systematic investigation, where the photogenerated electrons are demonstrated as the dominant reductive species to reduce Cr(VI) to Cr(III).

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“…Electro-reduction, chemical reduction, and micro-reduction are commonly used, while photocatalytic reduction emerged with more effective and low-cost property, as well as no producing any hazardous chemicals [11] . Generally, semiconductor photocatalyst TiO2 was used due to its durability, low cost, low toxicity, superhydrophilicity, and remarkable chemical and photochemical stability [11] . TiO2 structures are classified into several forms: nanoparticles, microspheres, nanrods, and nanosheets [14,15,16] .…”

Section: Photocatalytic Reductionmentioning

confidence: 99%

“…Especially, the MOFs' band gap is closely related to the HOMO-LUMO gap, and energy transfer can take place from the organic linker to the metal-oxo cluster within some MOFs under light irradiation [26] , which can be further tuned to achieve efficient light harvest via rational modification of the inorganic unit or organic linkers [27] . In previous researches, some typical MOFs (or their composites) were employed as photocatalysts for the reduction of Cr(VI) under visible light irradiation, including MIL-101(Fe), ZnO@ZIF-8, Pd@UiO-66(NH2), HPMo@MIL-100(Fe) and so on, with excellent reduction efficiency (100%) [11] .…”

Section: Photocatalytic Reductionmentioning

confidence: 99%

“…The increasingly mature nanotechnology promote the application of nanoadsorbent which enhances chemical reactivity and adsorbate/adsorbent interactions [1] . One the other hand, various kinds of nanomaterial also enhance the Cr(VI) reduction activity like TiO2 nanoparticles for photocatalytic reduction [10,11] . This article mainly showed newly technique for Cr(VI) removal including membrane separation [6,12,13] , photocatalytic reduction [14,15,16] , adsorption [17,18,19] , and application of nanotechnology [20,21] .…”

Section: Introductionmentioning

confidence: 99%

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Physio-chemical treatment technologies for chromium removal

Zhang¹,

Li²

2017

Proceedings of the 2016 4th International Conference on Renewable Energy and Environmental Technology (ICREET 2016)

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Abstract. The article reviews the technical applicability of various physio-chemical treatments for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A particular focus is given to membrane electrolysis, photocatalytic reduction, adsorption and the application of nanotechnology in Cr(VI) removal. About 50 published studies (2011)(2012)(2013)(2014)(2015)(2016)(2017) are reviewed. Liquid membrane and electrodialysis were combined. Metal-organic frameworks (MOFs) emerged to enhance photocatalytic reduction. It is evident that adsorption is the most frequently studied and widely applied for the treatment of Cr(VI). And nanotechnology is mainly applied to nanoadsorbent which exhibited both reduction and adsorption capabilities. In general, further researches on methods with cost-effectiveness, technical-applicability, and plant-simplicity are vital for heavy metal removal such as chromium.

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Photocatalytic Cr(VI) reduction in metal-organic frameworks: A mini-review

Cited by 560 publications

References 178 publications

The interplay between morphology and photocatalytic activity in ZnO and N-doped ZnO crystals

The interplay between morphology and photocatalytic activity in ZnO and N-doped ZnO crystals

Synergically Improving Light Harvesting and Charge Transportation of TiO2 Nanobelts by Deposition of MoS2 for Enhanced Photocatalytic Removal of Cr(VI)

Physio-chemical treatment technologies for chromium removal

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