Construction of a solar spectrum active SnS/ZnO p–n heterojunction as a highly efficient photocatalyst: the effect of the sensitization process on its performance

Jayswal, Shefali; Moirangthem, Rakesh S.

doi:10.1039/c8nj02098a

Cited by 48 publications

(19 citation statements)

References 50 publications

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“…These two bands are assigned to the Zn−O bond stretching vibration for tetrahedral and octahedral coordinations, respectively. 35 Other bands at 752.1, 1402.3, and 1563.3 cm −1 are attributed, respectively, to the vibrational frequency of the change in microstructural features of the ZnO lattice 36 and CC and CO group stretching vibrations. Finally, the bands at 2851.6 and 2923.9 cm −1 are attributed to the C−H stretching vibration and the band at 3145.9 cm −1 proved the presence of −OH groups on the ZnO surface.…”

Section: Resultsmentioning

confidence: 97%

“…The FTIR spectrum of Z1 is shown in Figure a, and it reveals two prominent bands at 573.07 and 658.11 cm –1 . These two bands are assigned to the Zn–O bond stretching vibration for tetrahedral and octahedral coordinations, respectively . Other bands at 752.1, 1402.3, and 1563.3 cm –1 are attributed, respectively, to the vibrational frequency of the change in microstructural features of the ZnO lattice and CC and CO group stretching vibrations.…”

Section: Resultsmentioning

confidence: 98%

“…Finally, the bands at 2851.6 and 2923.9 cm −1 are attributed to the C−H stretching vibration and the band at 3145.9 cm −1 proved the presence of −OH groups on the ZnO surface. 35 The undesired bonds CO and C−H are observed due to the formation of sodium acetate and zinc hydroxide from the mixture of zinc acetate and sodium hydroxide during the synthesis process of pure ZnO. Figure 2e represents the FTIR spectra for P1, which have some characteristic peaks at 615.9, 709.…”

Section: Resultsmentioning

confidence: 99%

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Oxygen-Vacancy-Dependent Photocatalysis for the Degradation of MB Dye Using UV Light and Observation of Förster Resonance Energy Transfer (FRET) in PANI-Capped ZnO

Chatterjee

Kar

2020

J. Phys. Chem. C

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In this work, pure ZnO, pure polyaniline (PANI), and a set of PANI-capped ZnO samples of various PANI concentrations are synthesized using the coprecipitation, oxidative polymerization, and ex situ methods, respectively. The X-ray diffraction results exhibit suppression in directional growth and shifting in ZnO-related peak positions in the capped samples with increasing PANI content. Interactions between ZnO and PANI chains are confirmed by Fourier transform infrared (FTIR) spectroscopy. The morphological characterizations (scanning electron microscopy (SEM) and transmission electron microscopy (TEM)) reveal the presence of an agglomerated spherelike structure of PANI on top of ZnO nanosheets. The X-ray photoelectron spectra (XPS) reveal a reduction in the density of surface as well as deep oxygen vacancy defects of ZnO after capping with PANI. The absorption spectra reveal an enhancement in the bipolaron band absorption for capped samples, which reinforces the presence of PANI chains. The photoluminescence spectra show a quenching in the emission intensity of ZnO after the addition of PANI; the overall quenching is discussed through concentration-dependent Förster resonance energy transfer (FRET) theory between ZnO (donor) and PANI (acceptor) between ZnO (donor) and PANI (acceptor). The sample capped with the least PANI content shows maximum quenching in the emission profile due to the encounter among the intradonor and the inter-donor–acceptor energy transfer mechanism. For rest of the capped samples, emissions are explained using the concentration-dependent inter-donor–acceptor FRET theory. Finally, the catalytic study of all capped samples and pure ZnO is performed through the degradation of methylene blue (MB) dye by irradiating UV light. Despite having quenched photoluminescence intensity, the results show a reduction in degradation efficiency for PANI-capped ZnO compared to pure ZnO contrary to the common trend. This is associated with the change in the density of oxygen vacancy sites of ZnO. Of the two oxygen vacancy sites, the surface oxygen vacancy sites play a major role as carrier trap centers and the deep oxygen vacancy sites delay the recombination process. The mechanism behind the effect of change in the density of these two vacancy types on photocatalysis is explained. Thus, by concentration-dependent FRET between ZnO and PANI and the oxygen vacancy defect density, the emission intensity and the photocatalytic activity of PANI-capped ZnO can be tuned.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

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Oxygen-Vacancy-Dependent Photocatalysis for the Degradation of MB Dye Using UV Light and Observation of Förster Resonance Energy Transfer (FRET) in PANI-Capped ZnO

Chatterjee

Kar

2020

J. Phys. Chem. C

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“…Zn lattice sites are replaced by Cu 2+ ions; therefore, the tunable bandgap nature of the photocatalyst is solely controlled by the doping ions. The location of the Fermi energy (E F ) level in the ZnO and SnS materials is shifted due to the impurity concentration, so that the CB of SnS lies just above the CB of the Cu 2+ -doped ZnO energy state, and the VB of SnS lies above the VB of Cu 2+ -doped ZnO energy level [11]. Thus, our novel heterogeneous ZnO-Cu/SnS structure with a ZnO-SnS interface can act as a possible medium for the transformation of photogenerated charge carriers on the surface of the nanocomposite through allowed self-activated lattice sites [44].…”

Section: Proposed Transport Mechanismmentioning

confidence: 99%

“…It behaves as an active photocatalyst under visible light irradiation with high absorption capacity. Thus, a ZnO-SnS heterojunction should exhibit enhanced absorption of solar energy and induce the separation of photogenerated charge carriers on the surface of the photocatalyst, thus achieving maximum photocatalytic performance [11]. Although the performance of heterojunction nanocomposites in the degradation of water pollutants is adequate, their low generation rate of electron-hole pairs limits their photocatalytic efficiency [12].…”

Section: Introductionmentioning

confidence: 99%

Facile Synthesis, Characterization, and Photocatalytic Activity of Hydrothermally Grown Cu2+-Doped ZnO–SnS Nanocomposites for MB Dye Degradation

Dharmana¹,

Gurugubelli²,

Masabattula³

et al. 2022

Catalysts

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The morphology, chemical composition, and doping process of metal oxides and sulfides play a significant role in their photocatalytic performance under solar light illumination. We synthesized Cu2+-doped ZnO–SnS nanocomposites at 220 °C for 10 h, using hydrothermal methods. These nanocomposites were structurally, morphologically, and optically characterized using various techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible absorption spectroscopy. Their photocatalytic activity (PCA) on methylene blue (MB) pollutant dye was examined under 150 W solar light illumination. Mixed-phase abundances with hexagonal ZnO and orthorhombic SnS structures were observed. TEM micrographs showed changes in morphology from spherical to nano-flake structures with an increasing doping concentration. XPS indicated the chemical states of the constituent elements in the nanocomposites. UV-visible absorption spectroscopy showed a decrease in the bandgap with an increasing doping concentration. Strong PCA was observed due to the separation of charge carriers, a change in bandgap, and a high light absorption ability under solar light irradiation. The measured photodegradation efficiency of the MB dye was approximately 97% after 2 h. The movement of the charge carriers and the bandgap alignment of the synthesized composites are briefly discussed.

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Charge Steering in Heterojunction Photocatalysis: General Principles, Design, Construction, and Challenges

Eshete

et al. 2023

Small Science

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Steering charge kinetics is a key to optimizing quantum efficiency. Advancing the design of photocatalysts (ranging from single semiconductor to multicomponent semiconductor junctions) that promise improved photocatalytic performance for converting solar to chemical energy, entails mastery of increasingly more complicated processes. Indeed, charge kinetics become more complex as both charge generation and charge consumption may occur simultaneously on different components, generally with charges being transferred from one component to another. Capturing detailed charge dynamics information in each heterojunction would provide numerous significant benefits for applications and has been needed for a long time. Here, the steering of charge kinetics by modulating charge energy states in the design of semiconductor–metal‐interface‐based heterogeneous photocatalysts is focused. These phenomena can be delineated by separating heterojunctions into classes exhibiting either Schottky/ohmic or plasmonic effects. General principles for the design and construction of heterojunction photocatalysts, including recent advances in the interfacing of semiconductors with graphene, carbon quantum dots, and graphitic carbon nitride are presented. Their limitations and possible future outlook are brought forward to further instruct the field in designing highly efficient photocatalysts.

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Construction of a solar spectrum active SnS/ZnO p–n heterojunction as a highly efficient photocatalyst: the effect of the sensitization process on its performance

Abstract: Comparison of photocatalytic activity of ex situ and in situ sensitized 1D SnS/ZnO in the photodegradation of multiple organic dyes under sunlight.

Cited by 48 publications

References 50 publications

Oxygen-Vacancy-Dependent Photocatalysis for the Degradation of MB Dye Using UV Light and Observation of Förster Resonance Energy Transfer (FRET) in PANI-Capped ZnO

Oxygen-Vacancy-Dependent Photocatalysis for the Degradation of MB Dye Using UV Light and Observation of Förster Resonance Energy Transfer (FRET) in PANI-Capped ZnO

Facile Synthesis, Characterization, and Photocatalytic Activity of Hydrothermally Grown Cu2+-Doped ZnO–SnS Nanocomposites for MB Dye Degradation

Charge Steering in Heterojunction Photocatalysis: General Principles, Design, Construction, and Challenges

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