scholarly journals Investigation of the Kinetics and Reaction Mechanism for Photodegradation Tetracycline Antibiotics over Sulfur-Doped Bi2WO6-x/ZnIn2S4 Direct Z-Scheme Heterojunction

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2123
Author(s):  
Yanbo Jiang ◽  
Kai Huang ◽  
Wei Ling ◽  
Xiandong Wei ◽  
Yijing Wang ◽  
...  
Keyword(s):  
Visible Light ◽  
Environmental Remediation ◽  
Active Sites ◽  
Rational Design ◽  
Organic Pollutant ◽  
Xps Spectra ◽  
Interfacial Transport ◽  
Photodegradation Rate ◽  
Photochemical Properties

The rational design of direct Z-scheme heterostructural photocatalysts using solar energy is promising for energy conversion and environmental remediation, which depends on the precise regulation of redox active sites, rapid spatial separation and transport of photoexcited charge and a broad visible light response. The Bi2WO6 materials have been paid more and more attention because of their unique photochemical properties. In this study, S2− doped Bi2WO6-x coupled with twin crystal ZnIn2S4 nanosheets (Sov−BWO/T−ZIS) were prepared as an efficient photocatalyst by a simple hydrothermal method for the removal of tetracycline hydrochloride (TCH). Multiple methods (XRD, TEM, XPS, EPR, UV vis DRS, PL etc.) were employed to systematically investigate the morphology, structure, composition and photochemical properties of the as-prepared samples. The XRD spectrum indicated that the S2− ions were successfully doped into the Sov−BWO component. XPS spectra and photoelectrochemical analysis proved that S2− served as electronic bridge and promoted captured electrons of surface oxygen vacancies transfer to the valence band of T−ZIS. Through both experimental and in situ electron paramagnetic resonance (in situ EPR) characterizations, a defined direct Z-scheme heterojunction in S-BWO/T−ZIS was confirmed. The improved photocatalytic capability of S-BWO/T−ZIS results ascribed that broadened wavelength range of light absorption, rapid separation and interfacial transport of photoexcited charge, precisely regulated redox centers by optimizing the interfacial transport mode. Particularly, the Sov−50BWO/T−ZIS Z-scheme heterojunction exhibited the highest photodegradation rate was 95% under visible light irradiation. Moreover, this heterojunction exhibited a robust adsorption and degradation capacity, providing a promising photocatalyst for an organic pollutant synergistic removal strategy.

In Situ-Grown Island-Shaped Hollow Graphene on TaON with Spatially Separated Active Sites Achieving Enhanced Visible-Light CO2 Reduction

ACS Catalysis ◽  
2020 ◽  
Vol 10 (24) ◽  
pp. 15083-15091
Author(s):  
Lang Pei ◽  
Yongjun Yuan ◽  
Wangfeng Bai ◽  
Taozhu Li ◽  
Heng Zhu ◽  
...  
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Co2 Reduction

scholarly journals Requirements for Beneficial Electrochemical Restructuring: A Model Study on a Cobalt Oxide in Selected Electrolytes

2021 ◽  
Author(s):  
Javier Villalobos ◽  
Diego Gonzales-Flores ◽  
Roberto Urcuyo ◽  
Mavis L. Montero ◽  
Götz Schuck ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Rational Design ◽  
Local Order ◽  
Current Increase ◽  
Model Study ◽  
Redox Active ◽  
Open Question ◽  
Diffraction Microscopy

<p>The requirements for beneficial materials restructuring into a higher performance OER electrocatalyst are still a largely open question. Here we use Erythrite (Co<sub>3</sub>(AsO<sub>4</sub>)<sub>2 </sub>8H<sub>2</sub>O) as a Co-based OER electrocatalyst to evaluate its catalytic properties during in-situ restructuring into an amorphous Co-based catalyst in four different electrolytes at pH 7. Using diffraction, microscopy and spectroscopy, we observed a strong effect in the restructuring kinetics depending of the anions in the electrolyte. Only carbonate electrolyte could activate the catalyst electrode, which we relate to its slow restructuring kinetics. While its turnover frequency (TOF) reduced from 2.84 O<sub>2 </sub>Co<sup>-1 </sup>s<sup>-1</sup> to a constant value of 0.10 O<sub>2</sub> Co<sup>-1 </sup>s<sup>-1</sup> after ~ 300 cycles, the number of redox active sites continuously increased, which explained the current increase of around 100%. The final activated material owns an adequate local order, a high Co oxidation state and a high number of redox-active Co ions, which we identify as the trinity for enhancing the OER activity. Thus, this work provides new insights into for the rational design of high-performance OER catalysts by electrochemical restructuring.</p>

scholarly journals Dual-defect-modified graphitic carbon nitride with boosted photocatalytic activity under visible light

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hideyuki Katsumata ◽  
Fumiya Higashi ◽  
Yuya Kobayashi ◽  
Ikki Tateishi ◽  
Mai Furukawa ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Environmental Remediation ◽  
Carbon Nitride ◽  
Order Rate Constant ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Strong Electron ◽  
Efficient Charge

Abstract The development of photocatalysts that efficiently degrade organic pollutants is an important environmental-remediation objective. To that end, we report a strategy for the ready fabrication of oxygen-doped graphitic carbon nitride (CN) with engendered nitrogen deficiencies. The addition of KOH and oxalic acid during the thermal condensation of urea led to a material that exhibits a significantly higher pseudo-first-order rate constant for the degradation of bisphenol A (BPA) (0.0225 min−1) compared to that of CN (0.00222 min−1). The enhanced photocatalytic activity for the degradation of BPA exhibited by the dual-defect-modified CN (Bt-OA-CN) is ascribable to a considerable red-shift in its light absorption compared to that of CN, as well as its modulated energy band structure and more-efficient charge separation. Furthermore, we confirmed that the in-situ-formed cyano groups in the Bt-OA-CN photocatalyst act as strong electron-withdrawing groups that efficiently separate and transfer photo-generated charge carriers to the surface of the photocatalyst. This study provides novel insight into the in-situ dual-defect strategy for g-C3N4, which is extendable to the modification of other photocatalysts; it also introduces Bt-OA-CN as a potential highly efficient visible-light-responsive photocatalyst for use in environmental-remediation applications.

The hydrothermal in situ construction of AgVO3/LaVO4 phase junctions for the efficient visible-light-driven disposal of pollutants and photoelectrocatalytic methanol oxidation

2020 ◽  
Vol 4 (5) ◽  
pp. 2569-2582
Author(s):  
Xiaoxiao Li ◽  
Kailian Zhang ◽  
Man Zhou ◽  
Kai Yang ◽  
Laixi Zou ◽  
...  
Keyword(s):  
Visible Light ◽  
Hydrothermal Method ◽  
Methanol Oxidation ◽  
Organic Pollutant ◽  
Facile Hydrothermal Method ◽  
Photoelectrocatalytic Oxidation ◽  
Oxidation Of Methanol ◽  
Visible Light Driven ◽  
One Step

The β-AgVO3/LaVO4 heterojunctions were synthesized via a one-step facile hydrothermal method, which exhibited excellent performances for degradation of organic pollutant in wastewater and photoelectrocatalytic oxidation of methanol.

Alkaline Earth Metal Oxide Nanocluster Modification of Rutile TiO2 (110) Promotes Water Activation and CO2 Chemisorption

2018 ◽  
Author(s):  
Michael Nolan
Keyword(s):  
Metal Oxide ◽  
Visible Light ◽  
Light Absorption ◽  
Environmental Remediation ◽  
Active Sites ◽  
Density Functional ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Alkaline Earth Oxide

Metal oxide photocatalysts are widely studied for applications in solar driven environmental remediation, antimicrobial activity, hydrogen production and CO<sub>2</sub> reduction to fuels. Common requirements for each technology include absorption of visible light, reduced charge carrier recombination and the ability to activate the initial molecule be it a pollutant, water or CO<sub>2</sub>. The leading photocatalyst is some form of TiO<sub>2</sub>. A significant amount of work has been undertaken to modifying TiO<sub>2</sub> to induce visible light absorption. The structure and composition of the catalyst should facilitate separation of electrons and holes and having active sites on the catalyst is important to promote the initial adsorption and activation of molecules of interest. In this paper we present a first principles density functional theory (DFT) study of the modification of rutile TiO<sub>2</sub> (110) with nanoclusters of the alkaline earth metal oxides (MgO, Ca, BaO) and we focus on the effect of surface modification on the key catalyst properties. The modification of rutile TiO<sub>2</sub> with CaO and BaO induces a predicted red shift in light absorption. In all cases, photoexcited electrons and holes localise on oxygen in the nanocluster and surface Ti sites, thus enhancing charge separation. The presence of these non-bulk alkaline earth oxide nanoclusters provides highly active sites for water and CO<sub>2</sub> adsorption. On MgO-rutile, water adsorbs molecularly and overcomes a barrier of only 0.36 eV for dissociation whereby hydroxyls are stabilised. On CaO- and BaO-modified rutile water adsorbs dissociatively. We attribute this to the high lying O 2p states in the alkaline earth oxide modifiers which are available to interact with water, as well as the non-bulk like geometry around the active site. Upon adsorption of CO<sub>2</sub> the preferred binding mode is as a tridentate carbonate-like species, as characterised by geometry and vibrational modes. The carbonate is bound by up to 4 eV. Thus these heterostructures can be interesting for CO<sub>2</sub> capture, helping alleviate the problem of CO<sub>2</sub> emissions.

scholarly journals Fabrication of Rh-doped TiO2 nanofibers for Visible Light Degradation of Rhodamine B

2011 ◽  
Vol 1352 ◽  
Author(s):  
Emilly A. Obuya ◽  
William Harrigan ◽  
Tim O’Brien ◽  
Dickson Andala ◽  
Eliud Mushibe ◽  
...  
Keyword(s):  
Visible Light ◽  
Rhodamine B ◽  
Environmental Remediation ◽  
Heterogeneous Catalysts ◽  
Low Cost ◽  
Organic Pollutant ◽  
Heterogeneous Photocatalysis ◽  
Tio2 Nanofibers ◽  
Visible Light Degradation ◽  
Surface Modified

ABSTRACTThe synthesis and application of environmentally benign, efficient and low cost heterogeneous catalysts is increasingly important for affordable and clean chemical technologies. Nanomaterials have been proposed to have new and exciting properties relative to their bulk counterparts due to the quantum level interactions that exist at nanoscale. These materials also offer enormous surface to volume ratios that would be invaluable in heterogeneous catalysis. Recent studies point at titanium dioxide nanomaterials as having strong potential to be applied in heterogeneous photocatalysis for environmental remediation and pollution control. This work reports the use of surface modified anatase TiO2 nanofibers with rhodium (Rh) nanoparticles in the photodegradation of rhodamine B (RH-B), an organic pollutant. The dimensions of TiO2 nanofibers were 150±50 nm in diameter and the size of the Rh nanoparticles was ~5 nm. The Rh-doped TiO2 catalyst exhibited an enhanced photocatalytic activity in photodegradation of rhodamine B under visible light irradiation, with 95 % degradation within 180 minutes reaction time. Undoped TiO2 did not show any notable phocatalytic activity under visible light.

scholarly journals Pyrene-based Conjugated Polymer/Bi2MoO6 Z-scheme Hybrids: Facile Construction and Sustainable Enhanced Photocatalytic Performance in Ciprofloxacin and Cr(VI) Removal under Visible Light Irradiation

2018 ◽  
Author(s):  
Xianglong Yang ◽  
Yonggang Xiang ◽  
Xuepeng Wang ◽  
Shu Li ◽  
Hao Chen ◽  
...  
Keyword(s):  
Visible Light ◽  
High Activity ◽  
Conjugated Polymer ◽  
Environmental Remediation ◽  
Photocatalytic Performance ◽  
Pt Nanoparticles ◽  
Coupling Reaction ◽  
Highly Active ◽  
Redox Ability

Search for appropriate materials with favorable staggered energy band arrangements is important and of great challenge to fabricate Z-scheme photocatalysts with high activity in visible light. In this study, we demonstrated a facile and feasible strategy to construct highly active organic-inorganic Z-scheme hybrids (P-BMO) with linear pyrene-based conjugated polymer (P17-E) and Bi2MoO6 via in-situ palladium-catalyzed cross-coupling reaction. Characterization results revealed C-O chemical bond formed at the heterointerface between P17-E and Bi2MoO6 after in-situ polycondensation and endowed the hybrids with observably improved photogenerated carries transfer capability. Visible light driven photocatalytic removal of ciprofloxacin and Cr(VI) were significantly enhanced after the incorporation of P17-E into Bi2MoO6 whether with the morphology of nanosheets, nanobelts or microspheres. Moreover, this P-BMO hybrids were also found to exhibit sustainable excellent photocatalytic performance after four runs of photocatalytic evaluation test, suggesting its high activity and stability. To better eliminate the redox ability enhancement of P-BMO, a reasonable Z-scheme electrons transferring mechanism between P17-E and Bi2MoO6 was proposed and proved by the determination of &bull;O2&ndash; and &bull;OH and Pt nanoparticles photodeposition experiments. This work might provide a viable source and insight into the design of Z-scheme photocatalysts with excellent redox ability for environmental remediation.

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