Photoelectrochemical and theoretical investigation of the photocatalytic activity of TiO<sub>2</sub> : N

Byzynski, Gabriela; Ribeiro, Rosane Aparecida; Lázaro, Sérgio Ricardo de; Ribeiro, Cauê

doi:10.1039/c6ra15825k

Cited by 49 publications

(24 citation statements)

References 59 publications

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“…Besides the current reduction density, the oxidation current density diminished under illumination as shown in Table 3. For k 0 calculation, the diffusion coefficients used were D O = D R = 7.26 × 10 −6 cm 2 s −1 and k 0 values are presented in Table 3 [43]. The k 0 values were slightly close, and TiO 2 -rGO heterostructure causes a decrease in electron transfer.…”

Section: Charge Electronic Transference Processmentioning

confidence: 99%

“…The flat band potential (V fb ) could be defined as a potential that no transfer charge occurs and is encountered through Buttler equation for each semiconductor. where j is the photocurrent density, N d is the number of charges donors, q is the transferred charge per ion, ɛ is the permittivity of the surroundings, ɛ 0 is the vacuum permittivity, I 0 is the current density difference, α is the optical absorption coefficient, V is the potential [43]. The flat band potential is obtained with the x-axis onset of the square photocurrent in Fig.…”

Section: Charge Electronic Transference Processmentioning

confidence: 99%

“…8b. The band gap values were added to the CB edge to obtain valence band edge, also indicating the modification in the VB edge [45].…”

Section: Charge Electronic Transference Processmentioning

confidence: 99%

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Direct photo-oxidation and superoxide radical as major responsible for dye photodegradation mechanism promoted by TiO2–rGO heterostructure

Byzynski

Volanti

Ribeiro

et al. 2018

J Mater Sci: Mater Electron

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The increase in photocatalytic activity of reduced graphene oxide-TiO 2 heterostructures under ultraviolet and visible illumination is already well known, as the photocatalyst mechanism modifications with heterostructure formation. However, which step in the degradation mechanism is modified with reduced graphene oxide-TiO 2 heterostructure formation has been not demonstrated yet. These specific modifications are caused by the alteration in reactive oxygen species production. In this way, the goal of this study is defined which reactive oxygen species are produced by reduced graphene oxide-TiO 2 heterostructure in the photocatalytic mechanism. A fast synthesis method to obtain this heterostructure by the microwave-assisted solvothermal method is presented, obtaining an improvement of photocatalytic efficiency, under UV and visible illumination. The non-hydrolytic method favors a better distribution of TiO 2 nanoparticles around the reduced graphene oxide structure and inhabits the charge carrier recombination, showing a faster electron transfer than TiO 2 samples. The RhB discoloration mechanism confirms that the reduced graphene oxide presence modifies the main reactive oxygen species produced. Under UV illumination, O 2 H* radical is the dominant reactive oxygen species produced by TiO 2. For the heterostructure, the direct oxidation by oxygen vacancy is the primary mechanism step. Under visible illumination, O 2 H* is the main reactive oxygen species for both materials. The results present a better understanding of principal reasons related to the improvement in photocatalytic activity and could be useful in semiconductor heterostructure design.

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Section: Charge Electronic Transference Processmentioning

confidence: 99%

Section: Charge Electronic Transference Processmentioning

confidence: 99%

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Direct photo-oxidation and superoxide radical as major responsible for dye photodegradation mechanism promoted by TiO2–rGO heterostructure

Byzynski

Volanti

Ribeiro

et al. 2018

J Mater Sci: Mater Electron

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“…The structure modification of TiO 2 have been investigating by many approaches such as the combination of the quantum dot sensitization, chemical doping/loading the metal or the narrow gap semiconductor coupling to enhance light absorption and obtain a higher PEC efficiency [6][7][8]. These works aim to create acceptor states above the valence band (VB) or donor states below the conduction band (CB) of TiO 2 [9]. Recently, a new strategy to generate a new form of TiO 2 which is called black TiO 2 , with self-defect states inside its energy structure playing role as carrier traps below the CB of TiO 2 to narrow the band gap for boosting the interaction of the material with the light irradiation [10].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Some Characterizations of Black TiO\(_2\) Nanotubes Via Spectroscopic Methods

Nguyen¹,

Cao²,

Le³

et al. 2019

Comm. in Phys.

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The black TiO\(_2\) with substantial Ti\(^3+\) and oxygen vacancies exhibit an excellent photoelectrochemical water-splitting performance due to the improved charge transport the extended visible light response. In this study, black TiO\(_2\) nanotube arrays synthesized by the anodization method, and then, they have been investigated some characterizations by spectroscopic methods such as UV-visible reflectance (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and photoluminescence spectrum. The results showed that some highlighted properties of the black TiO2 nanotube arrays and they could apply for water-splitting effect.

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“…(9)); in such an equation, m* is the effective mass of the charge carrier, k is the wave vector, ℏ is the reduced Planck constant and E refers to the energy of an electron at wave vector k in that band. In order to guarantee the validation of the parabolic approximation within the CBM and VBM, the parabolic fitting is performed considering a difference of 1 meV around the CBM and VBM regions [45][46][47][48].…”

Section: Density Of States (Dos) and Band Structurementioning

confidence: 99%

Quantum Chemistry Applied to Photocatalysis with TiO2

Lázaro¹,

Ribeiro²,

Lacerda³

2017

Titanium Dioxide

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Heterogeneous catalysis is a topic very studied in science. Its application in technologies of energy conversion, water purification, chemical synthesis, car catalytic converter and so on is studied. Recently, the TiO2 material in anatase and rutile phases has been used extensively in photocatalytic systems; its band-gap is localized in visible and ultra-violet spectra, proportioning a good material for generation of chemical radicals. Nowadays, the density functional theory (DFT) is shown as a great tool to simulate all types of materials and the possibilities to simulate bulk and surfaces of materials importance in last few decades. Recently, quantum periodic calculations based on DFT methods have been widely used to simulate materials and the main functionals applied are PBE, PBE0 and B3LYP; they are important for doping and adsorption theoretical investigations and are present in various simulation programs, such as, Crystal, Wien, Vasp and others. This methodology has investigate the influence of dangling bonds, cationic and anionic doping, charge transfer, surface energy and more quantum properties. Quantum chemistry tools, in particular, DFT methods, are key points to develop high quality research and technology once theoretical calculations are important to guide and understand the molecular design in photocatalysis.

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Photoelectrochemical and theoretical investigation of the photocatalytic activity of TiO₂ : N

Abstract: In N-doping on TiO2 nanomaterial occurs a big decrease of band-gap (1 eV); however, its photocatalysis is low. We clarify such fact from effective mass, i.e., the electron–hole recombination is more than creation of electron–hole pair.

Cited by 49 publications

References 59 publications

Direct photo-oxidation and superoxide radical as major responsible for dye photodegradation mechanism promoted by TiO2–rGO heterostructure

Direct photo-oxidation and superoxide radical as major responsible for dye photodegradation mechanism promoted by TiO2–rGO heterostructure

Investigation of Some Characterizations of Black TiO\(_2\) Nanotubes Via Spectroscopic Methods

Quantum Chemistry Applied to Photocatalysis with TiO2

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Photoelectrochemical and theoretical investigation of the photocatalytic activity of TiO2 : N

Abstract: In N-doping on TiO2 nanomaterial occurs a big decrease of band-gap (1 eV); however, its photocatalysis is low. We clarify such fact from effective mass, i.e., the electron–hole recombination is more than creation of electron–hole pair.

Cited by 49 publications

References 59 publications

Direct photo-oxidation and superoxide radical as major responsible for dye photodegradation mechanism promoted by TiO2–rGO heterostructure

Direct photo-oxidation and superoxide radical as major responsible for dye photodegradation mechanism promoted by TiO2–rGO heterostructure

Investigation of Some Characterizations of Black TiO\(_2\) Nanotubes Via Spectroscopic Methods

Quantum Chemistry Applied to Photocatalysis with TiO2

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Photoelectrochemical and theoretical investigation of the photocatalytic activity of TiO₂ : N