scholarly journals Photoelectrochemical Degradation of Organic Pollutants on a La3+ Doped BiFeO3 Perovskite

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1069
Author(s):  
Oluchi V. Nkwachukwu ◽  
Charles Muzenda ◽  
Babatope O. Ojo ◽  
Busisiwe N. Zwane ◽  
Babatunde A. Koiki ◽  
...  
Keyword(s):  
Organic Pollutants ◽  
Diffuse Reflectance ◽  
Electrochemical Impedance ◽  
Bismuth Ferrite ◽  
Charge Carriers ◽  
Current Response ◽  
Orange Ii ◽  
Applied Bias ◽  
Bias Potential ◽  
Light Region

Towards nonconventional wastewater treatment methods for the degradation of organic pollutants in wastewater, a perovskite-based photoelectrochemical system was developed. Bismuth ferrite doped with lanthanum (La-BiFeO3, La-BFO) perovskite was synthesised through a hydrothermal method with low calcination temperature for the photoelectrochemical degradation of orange II dye and other cocktails of dyes. Photoanodes were prepared by the deposition of the perovskites on a fluorine-doped tin oxide (FTO) substrate. The photoanodes were characterised using XRD, FESEM, FTIR and UV-vis diffuse reflectance. The photoelectrochemical properties of the synthesised photoanodes were investigated with chronoamperometry and electrochemical impedance spectroscopy (including Mott–Schottky analysis). The results show that all La3+-doped BFO photoanodes exhibited a higher absorption edge in the visible light region than the undoped BFO. The photocurrent response of 10% La-BFO (the best performing electrode) exhibited a three times higher current response than the pure BFO. In addition, the electrode exhibited a good degradation efficiency of 84.2% within 120 min with applied bias potential of 2 V at a pH of 7. EIS studies showed a significant enhancement of the interfacial electron transfer of the charge carriers. The enhancements in electrode performances were attributed to the synergistic effect of the applied bias potential and the introduction of La3+ into the BFO matrix. This study therefore shows that the photoelectrocatalytic performance of BFO for water treatment can be improved by the introduction of perovskites-doping ions such as La3+.

Photo-Current Enhancement at Cu/p-Cu2O/rGO- Electrolyte Interface

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
S.P.A.U.K. Samarakoon ◽  
C.A.N. Fernando
Keyword(s):  
Diffuse Reflectance ◽  
Electrochemical Cell ◽  
Time Development ◽  
Charge Carriers ◽  
Electrochemical Cells ◽  
Current Action ◽  
Electrolyte Interface ◽  
Reduced Graphene ◽  
Efficient Charge ◽  
Photo Current

A considerable photo-current enhancement was found at the Cu/p-Cu2O/rGO-electrolyte interface in a photo-electrochemical cell with compared to that of Cu/p-Cu2O-electrolyte interface. The reason for the photo-current enhancement may be due to the efficient charge separation process provided at Cu/p-Cu2O/rGO-electrolyte interface. Here rGO (reduced graphene oxide) acts as an electron acceptor for the photo-generated charge carriers as it readily accept electrons from the conduction band of p-Cu2O. rGO was synthesized using electro-phoretic deposition (EPD) technique. Fabricated samples were characterized using diffuse reflectance spectra, photo-current action spectra and the time development of the photocurrent of photo-electrochemical cells.

UNUSUAL ELECTROCHEMICAL RESPONSE OF ELECTROCHEMICAL ETCHING ON MULTIWALLED CARBON NANOTUBES

NANO ◽  
2008 ◽  
Vol 03 (06) ◽  
pp. 461-467 ◽  
Author(s):  
JIAN-SHAN YE ◽  
GUANGQUAN MO ◽  
WEI DE ZHANG ◽  
XIAO LIU ◽  
FWU-SHAN SHEU
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Electrochemical Impedance ◽  
Electrochemical Etching ◽  
Current Response ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Oxidation Of Glucose ◽  
Total Disappearance ◽  
Electrocatalytic Effects

Multiwalled carbon nanotubes (MWNTs) can be etched at potentials more positive than 1.7 V versus Ag / AgCl (3 M KCl ) in 0.2 M HNO 3. The electrochemically etched MWNTs show an increase in electrochemical impedance and sluggish electron transfer kinetics, and lose the electrocatalytic effects toward the oxidation of glucose, H 2 O 2, uric acid (UA) and L-ascorbic acid (L-AA). Transmission electron microscope (TEM) images reveal that the nanotube tips are cut off by electrochemical oxidation. This may lead to the degradation of electrocatalytic ability in the MWNTs. Furthermore, the current response after different electrochemically etched cycles shows that the electrocatalytic ability of the MWNTs toward different molecules can be tuned by etched cycles. For example, five etched cycles leads to the total disappearance of the oxidative response to L-AA, with the remaining over 50% of the UA current response in the L-AA and UA mixture. Thus, electrochemical etching is a simple yet novel way to tune the electrocatalytic reactivity and improve the selectivity of the MWNTs.

The Effective Temperature of Dust Impact Plasmas — Olivine Dust on Tungsten Target

2021 ◽  
Author(s):  
Jiří Pavlů ◽  
Samuel Kočiščák ◽  
Åshild Fredriksen ◽  
Michael DeLuca ◽  
Zoltan Sternovsky
Keyword(s):  
Negative Charge ◽  
Negative Ions ◽  
Charge Carriers ◽  
Dust Particles ◽  
Applied Bias ◽  
Control Grid ◽  
Impact Speed ◽  
Positive Ions ◽  
Effective Temperatures ◽  
The Impact

<p>We experimentally observe both positive and negative charge carriers in impact plasma and estimate their effective temperatures. The measurements are carried on a dust accelerator using polypyrrole (PPy)-coated olivine dust particles impacting tungsten (W) target in the velocity range of 2–18 km/s. We measure the retained impact charge as a function of applied bias potential to the control grid. The temperatures are estimated from the data fit. The estimated effective temperatures of the positive ions are approximately 7 eV and seems to be independent of the impact speed. The negative charge carriers' temperatures vary from as low as 1 eV for the lowest speeds to almost ten times higher speeds. The presented values differ significantly from previous studies using Fe dust particles. Yet, the discrepancy can be attributed to a larger fraction of negative ions in the impact plasma that likely originates from the PPy coating.</p>

Construction of a novel 2D-2D heterojunction by coupling covalent organic framework and In2S3 for photocatalytic removal of organic pollutants with high efficiency

2021 ◽  
Author(s):  
Luqiu Li ◽  
Dongguang Yin ◽  
Xiandi Guo
Keyword(s):  
Visible Light ◽  
Hydrogen Evolution ◽  
Organic Pollutants ◽  
High Efficiency ◽  
Crystalline Material ◽  
Charge Carriers ◽  
Covalent Organic Frameworks ◽  
Covalent Organic Framework ◽  
Photocatalytic Removal ◽  
Visible Light Driven

Covalent organic frameworks (COFs) representing an emerging class of porous crystalline material have shown promising visible-light-driven hydrogen evolution activity. However, they have a high recombination ratio of charge carriers and...

Photocatalytic Activity of Bismuth Ferrite Nanoparticles Synthesized via Sol-Gel Route

2019 ◽  
Vol 233 (5) ◽  
pp. 595-607 ◽  
Author(s):  
Mohsin Siddique ◽  
Noor Muhammad Khan ◽  
Muhammad Saeed
Keyword(s):  
Visible Light ◽  
Photocatalytic Degradation ◽  
Irradiation Time ◽  
Bismuth Ferrite ◽  
Sol Gel ◽  
Reaction System ◽  
Light Conditions ◽  
X Ray Diffraction ◽  
Light Region ◽  
Gel Technique

Abstract Nanosized, magnetically separable bismuth ferrite (BFO) nanoparticles, pertaining a crystallite size in the range of 14–15 nm were prepared via facile sol-gel technique. The product was characterized by scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The product was explored for the photocatalytic mineralization of rhodamine B (RB) dye in aqueous medium. The effect of different investigational parameters such as amount of photocatalyst, initial dye concentration and irradiation time on the photocatalytic degradation of RB was studied. The results reveal that the catalyst shows good degrading ability under normal pH and visible light conditions. BFO nanoparticles demonstrated a strong absorption ability in the visible-light region, which lead to efficient photocatalytic degradation of RB dye The reaction system was heterogeneous in nature in which the catalyst can be separated by a normal magnet.

Polycations and Their Complexes

1977 ◽  
Vol 47 (8) ◽  
pp. 530-534 ◽  
Author(s):  
B. Courtney ◽  
J. B. Lawton
Keyword(s):  
Free Energy ◽  
Methyl Orange ◽  
Diffuse Reflectance ◽  
Color Change ◽  
Reflectance Spectra ◽  
Orange Ii ◽  
Alternative Treatments ◽  
Anionic Dyes ◽  
Diffuse Reflectance Spectra ◽  
Diethylaminoethyl Cellulose

Free-energy changes have been determined for the binding of the anionic dyes Orange II and Methyl Orange to diethylaminoethyl cellulose and triethylaminoethyl cellulose. These polycations resemble wool and other natural polycations in some respects. It is shown, however, that the Gilbert-Rideal theory is not satisfactory for cellulosic polycations, and alternative treatments are given. It was found that the order of binding of some simple anions was I- > Br- > Cl-. The sulphate ion behaved anomalously and appeared to be sensitive to changes in the intersite distance. Diffuse reflectance spectra showed evidence of a metachromatic color change in the spectrum of the bound dyes.

scholarly journals Evaluation of Photocatalysis Effect of Stainless Steel Mesh Coated with Nitrides, Oxynitrides and Transition Metals Cr and Ti on the Degradation of Orange II Dye

Proceedings ◽  
2019 ◽  
Vol 29 (1) ◽  
pp. 14 ◽  
Author(s):  
Mouele ◽  
Dinu ◽  
Parau ◽  
Missengue ◽  
Vladescu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Drinking Water ◽  
Wastewater Treatment ◽  
Transition Metals ◽  
Organic Pollutants ◽  
Orange Ii ◽  
Stainless Steel Mesh ◽  
Steel Mesh ◽  
Treatment Processes ◽  
Water And Wastewater

The increased detection of organic pollutants in drinking water and their resistance to degradation by wastewater treatment processes has motivated the development of more efficient, affordable and sustainable methods of purification of drinking water and wastewater. [...]

scholarly journals Electrochemical Study of Anodized Titanium in Phosphoric Acid

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
M. Khadiri ◽  
M. Elyaagoubi ◽  
R. Idouhli ◽  
Y. Koumya ◽  
O. Zakir ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Charge Carriers ◽  
Flat Band ◽  
X Ray Diffraction ◽  
X Ray ◽  
Type Semiconductor ◽  
Anodized Titanium ◽  
Spectroscopy Studies ◽  
Schottky Model ◽  
Good Agreement

The anodization of the Ti-Cu (2%) alloy was carried out in a 5M H3PO4 solution for 2 minutes. The obtained layers are characterized by XPS, X-ray diffraction, and Raman spectroscopy. The results showed that the obtained films are composed of poorly crystallized TiO2 oxide. Electrochemical Impedance spectroscopy studies revealed that the thickness of the formed film increases with increasing anodization potential. Additionally, the resistance of charge transfer becomes higher when the anodization potential increases. Thus, the Mott Schottky model revealed that the formed film is an n-type semiconductor. The density of charge carriers is in good agreement with those found in the literature. Also, it is found that the flat-band potential increases with increasing treatment potential.

One-Pot Hydrothermal Synthesis of Sulfur-Doped SnO2 Nanoparticles and their Enhanced Photocatalytic Properties

NANO ◽  
2016 ◽  
Vol 11 (03) ◽  
pp. 1650035 ◽  
Author(s):  
Lin Ma ◽  
Limei Xu ◽  
Xuyao Xu ◽  
Xiaoping Zhou ◽  
Lingling Zhang
Keyword(s):  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Sno2 Nanoparticles ◽  
Light Response ◽  
One Pot ◽  
X Ray ◽  
Transmission Electron ◽  
Light Region ◽  
Vis Spectroscopy

Sulfur-doped SnO2 nanoparticles with ultrafine sizes have been successfully prepared by a one-pot hydrothermal method. The obtained samples are characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), thermogravimetric (TG), analyzer UV-Vis spectroscopy, photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the doping level of sulfur element as well as the bandgaps of SnO2 can be controlled to a certain extent by varying the amount of L-cysteine (L-cys). When evaluated as photocatalysts in the degradation of rhodamine B (RhB) and reduction of Cr(VI) under visible light region, the resultant sulfur-doped SnO2 nanoparticles demonstrate obviously enhanced photocatalytic activities due to the markedly improved visible light response and effective separation of the photo-generated electron–hole pairs.

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