Towards visible-light photocatalysis for environmental applications: band-gap engineering versus photons absorption—a review

Marcelino, Rafaela Brito Portela; Amorim, Camila C.

doi:10.1007/s11356-018-3117-5

Cited by 92 publications

(41 citation statements)

References 151 publications

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“…Photocatalytic degradation can be assumed, since only a discrete 0.6% removal was observed under dark conditions due to adsorption on the porous Nb 2 O 5 . The slight photocatalytic removal under solar irradiation could be justified by the faster recombination Reaction (3), which diminishes the available oxidants (i.e., h vb + and OH) [17,22]. The strategic use of selective e cb − scavengers may synergistically enhance the photocatalytic response by inhibiting the extent of Reaction (3) [16,26].…”

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

“…The synergetic effect observed between Nb2O5 and ecbscavenger H2O2 can be explained by the enhanced generation of • OH from Reaction (2) due to the significant reduction of the recombination rate of Reaction (3) [26,36]. This effect results in a consequent increase in the availability of reactive oxygen species on the Nb2O5 photocatalyst surface, and then the increased oxidation capabilities of the system degrading the azo dye molecule [17,23]. The synergetic effect observed between Nb 2 O 5 and e cb − scavenger H 2 O 2 can be explained by the enhanced generation of OH from Reaction (2) due to the significant reduction of the recombination rate of Reaction (3) [26,36].…”

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

“…For this reason, the role of H 2 O 2 concentration in solution was studied as a rate driving parameter for decolorization. Figure 6 shows [17,37]. One of the main processes that decreases performance is the oxidation of excess H 2 O 2 by OH following Reaction (8) [24,26].…”

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

“…It should be noted that further increase in H2O2 concentration resulted in a decrease in performance, achieving a lower color removal of only 77.2% after 80 min of Nb2O5 photocatalytic treatment. This phenomenon can be explained by the acceleration of concomitant waste reactions [17,37]. One of the main processes that decreases performance is the oxidation of excess H2O2 by • OH following Reaction (8) [24,26].…”

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

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Niobium Oxide Catalysts as Emerging Material for Textile Wastewater Reuse: Photocatalytic Decolorization of Azo Dyes

et al. 2019

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Niobium-based metal oxides are emerging semiconductor materials with barely explored properties for photocatalytic wastewater remediation. Brazil possesses the greatest reserves of niobium worldwide, being a natural resource that is barely exploited. Environmental applications of solar active niobium photocatalysts can provide opportunities in the developing areas of Northeast Brazil, which receives over 22 MJ m2 of natural sunlight irradiation annually. The application of photocatalytic treatment could incentivize water reuse practices in small and mid-sized textile businesses in the region. This work reports the facile synthesis of Nb2O5 catalysts and explores their performance for the treatment of colored azo dye effluents. The high photoactivity of this alternative photocatalyst makes it possible to quickly obtain complete decolorization, in less than 40 min of treatment. The optimal operational conditions are defined as 1.0 g L−1 Nb2O5 loading in slurry, 0.2 M of H2O2, pH 5.0 to treat up to 15 mg L−1 of methyl orange solution. To evaluate reutilization without photocatalytic activity loss, the Nb2O5 was recovered after the experience and reused, showing the same decolorization rate after several cycles. Therefore, Nb2O5 appears to be a promising photocatalytic material with potential applicability in wastewater treatment due to its innocuous character and high stability.

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Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

Section: Photocatalytic Activity On Azo Dye Decolorizationmentioning

confidence: 99%

See 2 more Smart Citations

Niobium Oxide Catalysts as Emerging Material for Textile Wastewater Reuse: Photocatalytic Decolorization of Azo Dyes

et al. 2019

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“…The electronic band structure determines the physical and chemical properties of materials, such as optical absorption, superconductivity, magnetoresistance, catalytic and photocatalytic activity [1][2][3]. Thus, knowledge about the electronic band structure is of prime importance to understand materials function and reactivity.…”

Section: Introductionmentioning

confidence: 99%

Custom-Made Cell Designed for Thermal Studies and <i>In Situ</i> X-Ray Spectroscopy Experiments

2020

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In situ measurements provide an opportunity for investigating not only the initial and final states of the process, but also intermediate states within the process. In particular, X-ray spectroscopy techniques have become an important tool to obtain relevant information (oxidation state, electronic structure, local bonding environment) during material's transformation under real reaction conditions. Herein, we describe a novel cell specifically designed for ex situ and in situ thermal studies with X-ray spectroscopy techniques. A key feature of this setup is the possibility to work at high temperatures (up to 1370 • C) and under different atmospheres (from inert to reactive). The cell is conveniently designed to allow measurements in in-house laboratories as well as large-scale synchrotron facilities. The setup allows also to perform X-ray spectroscopy measurements in both fluorescence and transmission mode. In order to demonstrate the capabilities of the designed cell, thermal oxidation of metallic titanium to titanium dioxide was studied. First, the manufactured cell was tested in the laboratory and ex situ X-ray photoelectron measurements were performed for the Ti metal discs heated at different temperatures. Then, the setup was mounted on SuperXAS beamline at Swiss Light Source, and Ti K-edge X-ray absorption spectroscopy and valence-to-core X-ray emission spectra were collected during the thermal oxidation process. The combination of these techniques provided information about the electronic structure of occupied and unoccupied states around the Fermi level.

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Scalable and Recyclable Heterogeneous Organo‐photocatalysts on Cotton Threads for Organic and Polymer Synthesis

et al. 2020

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As a highly efficient and environmentally friendly technology to address the challenges of sustainable chemistry and engineering, heterogeneous visible-light photoredox catalysis has been of great potential in organic and polymer synthesis. Eosin Y (EY), one of the commonly used organo-photoredox catalysts, has been immobilized onto commercial cotton threads via a straightforward method and single-step coupling reaction to prepare a scalable and recyclable heterogeneous photocatalyst. The immobilized EY is capable of generating singlet oxygen for organic transformations (e. g. oxidation of thioethers) in the presence of molecular oxygen, and effectively catalysing visiblelight photoinduced electron/energy transfer À reversible addition À fragmentation chain transfer polymerizations of various functional monomers for the synthesis of well-defined polymers in diverse "green" solvents. Facile separation and recovery of the cotton thread supported EY enable the reuse of the catalyst over multiple reaction cycles with well-retained catalytic efficiency.

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Towards visible-light photocatalysis for environmental applications: band-gap engineering versus photons absorption—a review

Cited by 92 publications

References 151 publications

Niobium Oxide Catalysts as Emerging Material for Textile Wastewater Reuse: Photocatalytic Decolorization of Azo Dyes

Niobium Oxide Catalysts as Emerging Material for Textile Wastewater Reuse: Photocatalytic Decolorization of Azo Dyes

Custom-Made Cell Designed for Thermal Studies and <i>In Situ</i> X-Ray Spectroscopy Experiments

Scalable and Recyclable Heterogeneous Organo‐photocatalysts on Cotton Threads for Organic and Polymer Synthesis

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