Visible-light photocatalytic activity of TiO2/ZnS nanocomposites prepared by homogeneous hydrolysis

Type of publicationArticle (peer-reviewed) AbstractThis progress review describes our work on the design of new TiO2 based photocatalysts. The key concept is the formation of composite structures through the modification of anatase and rutile TiO2 with molecular-sized nanoclusters of metals oxides. Our density functional theory (DFT) level simulations have been compared with experimental work synthesizing and characterizing surface modified TiO2. We use DFT to show that nanoclusters of metal oxides such as TiO2, SnO/SnO2, PbO/PbO2, ZnO and CuO are stable when adsorbed at rutile and anatase surfaces and can lead to a significant red shift in the absorption edge which will induce visible light absorption; this is the first requirement for a useful photocatalyst. We determine the origin of the red shift and the fate of excited electrons and holes. For p-block metal oxides the oxidation state of Sn and Pb can be used to modify the magnitude of the red shift and its mechanism. We describe comparisons of recent experimental studies of surface modified TiO2 that validate our DFT simulations. These nanocluster-modified TiO2 structures 2 form the basis of a new class of photocatalysts which will be useful in oxidation reactions and with a correct choice of nanocluster modified can be applied to other reactions.

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“…A quantitative comparison is not possible as the alignments in ref [107] are determined using [ [108][109][110][111] .…”

Section: + To Induce Visible Light Absorptionmentioning

confidence: 99%

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

et al. 2016

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“…Although, its band gap energy is high, however the activity at visible light indicates that actually if UV light provides the photons required for the electron transfer from valence band to conduction band. Therefore, the energy of of photon is related to wavelength, Meanwhile, the overal energy input to a photocatalytic process is dependent upon the light intensity [3]. It is supported by the data of the number of photon absorbed by ZnSTiO2/Graphite per second ( Table 3) that increased one order after ZnS deposition.…”

Section: Resultsmentioning

confidence: 76%

“…The increasing of photocatalytic activity by the presence of ZnS might also be attributed to the formation of preassociated complex between ZnS/TiO2 composite with isopropanol molecules, the synergetic effect of ZnS and TiO2, and strong absorption between isopropanol molecules and ZnS/TiO2 composite [11]. The visible light photoactivity was also founded in the nanocomposite of TiO2/ZnS that was synthesized by homogeneus hydrolysis in aqueous solution with thioacetamide in the degradation of orange II dye solution [3]. Although, its band gap energy is high, however the activity at visible light indicates that actually if UV light provides the photons required for the electron transfer from valence band to conduction band.…”

Section: Resultsmentioning

confidence: 98%

“…The composite also show higher efficiency of visible-light photo catalytic activity to degrade the aqueous parathion methyl compared to pure anatase TiO2 and ZnS nanoparticle [8]. Meanwhile, the TiO2/ZnS composite that was prepared by homogeneus hydrolysis of titanium oxo-sulphate and zinc sulphate in aqueous solution with thioacetamide, exhibits better UV characteristic compared to the bulk TiO2 and ZnS [9]. A homogeneus ZnS coating onto TiO2 nanoparticle also can be prepared by sonochemical method [10] and also by a microemulsionmediated solvothermal method that produced an enhanced photocatalytic activity due to strong adsorption of the targeted molecules at the ZnS/TiO2 nanocomposites surface area [11].…”

Section: Introductionmentioning

confidence: 99%

“…Modification of TiO2 semiconductor has been conducted by several reseachers [1][2][3] with the aim to increase the photo catalytic activity of TiO2 especially at visible light radiation. TiO2 is the most studied material for photo catalysis due to its stability, unexpensive, ease of fabrication and produsing a significant voltage [4].…”

Section: Introductionmentioning

confidence: 99%

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The Optical Properties and Photo catalytic Activity of ZnS-TiO2/Graphite Under Ultra Violet and Visible Light Radiation

Rahmawati

Wulandari

Murni

et al. 2015

Bull. Chem. React. Eng. Catal.

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This paper discuss research about the optical properties and photo catalytic activity of TiO2 film on graphite substrate and its modification with ZnS. The optical properties investigated are the light response at various light wavelength and the gap energy (Eg). Meanwhile, the photocatalytic activity was studied from isopropanol degradation to determine the Quantum Yield (QY) and kinetics of reaction. The results show that the TiO2 layer is consisted of rutile and anatase phases. Meanwhile, the ZnS peaks are at 2θ 27.91 o and 54.58 o . The gap energy of TiO2/G consist of two band gap representing the band gap of rutile and anatase. The ZnS deposition shifted the band gap into single gap of 3.40 eV which is in between the gap energy of single TiO2 and single ZnS. The isopropanol degradation with TiO2/G photocatalyst under visible light radiation did not produce any new peaks representing product. Meanwhile, the photocatalytic process under 380 nm light produce new peaks representing the electronic transition of acetone. The isopropanol degradation with ZnS-TiO2/Graphite produced new peaks that indicates the photocataytic activity of ZnS-TiO2/Graphite whether under UV or visible light radiation. Significant role of ZnS also proven by the increase of the QY values and the increase of rate constant, k.

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Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

2020

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Composite materials whose band alignment induces a favorable separation of photogenerated electrons and holes often reveal a stronger photocatalytic activity compared to their separate components. As shown by experiments, titania composites display a heterojunction between the anatase (101)‐(001) surfaces, where the former stabilizes electrons and the latter the holes. In principle, an even more efficient carriers separation is achieved if a third component with high hole‐stabilizing capability, ZnS(110), is growth on anatase (001). However, even though this ternary TiO2/TiO2/ZnS composite material displays good photoactivity, it does not overperform the TiO2/TiO2 one. In this paper an explanation of this evidence is provided by means of periodic hybrid DFT calculations, showing how Coulomb forces play a role against the separation of charge carriers predicted based on the relative energy of the band edges. This highlights the necessity to explicitly account for structural and electronic junction's effects, as well as charge carriers’ localization.

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Visible-light photocatalytic activity of TiO2/ZnS nanocomposites prepared by homogeneous hydrolysis

Cited by 98 publications

References 31 publications

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

The Optical Properties and Photo catalytic Activity of ZnS-TiO2/Graphite Under Ultra Violet and Visible Light Radiation

Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study

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Visible-light photocatalytic activity of TiO2/ZnS nanocomposites prepared by homogeneous hydrolysis

Cited by 98 publications

References 31 publications

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO2

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO2

The Optical Properties and Photo catalytic Activity of ZnS-TiO2/Graphite Under Ultra Violet and Visible Light Radiation

Charge Carriers Cascade in a Ternary TiO2/TiO2/ZnS Heterojunction: A DFT Study

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Product

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Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Charge Carriers Cascade in a Ternary TiO₂/TiO₂/ZnS Heterojunction: A DFT Study