scholarly journals Rapid reduction of nitroarenes photocatalyzed by an innovative Mn3O4/α-Ag2WO4 nanoparticles

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mohamed Mokhtar Mohamed ◽  
Hassan El-Farsy
Keyword(s):  
Diffuse Reflectance ◽  
Reaction Medium ◽  
Linear Sweep Voltammetry ◽  
Charge Carriers ◽  
Linear Sweep ◽  
Rapid Reduction ◽  
Composite Photocatalyst ◽  
Mild Conditions ◽  
Transient Photocurrent ◽  
Reduction Activity

AbstractA novel photocatalyst based on the design of P-N heterojunction between hollow spherical Mn3O4 and nanorods shape of α-Ag2WO4 is synthesized using a sonication-deposition–precipitation route. The nanocomposite Mn3O4/α-Ag2WO4(60%) exhibits a great potential towards nitroarenes (including 4-nitrophenol, 4-nitro-aniline and 4-Nitro-acetanilide) reduction under visible light irradiation exceeding that of Mn3O4/α-Ag2WO4(40%) as well as their individual counterparts (3–5%). The Mn3O4/α-Ag2WO4(60%) catalyst exhibited an excellent photo-reduction activity comprised of 0.067 s−1 towards 4-nitrophenol (0.001 M) in only 60 s reaction time using NaBH4 (0.2 M). This was due to the successful formation of the Mn3O4/α-Ag2WO4 composite as validated by XRD, TEM-SAED, XPS, FTIR, UV–Vis diffuse reflectance and PL techniques. Decreasing the Eg value into 2.7 eV, the existence of a new (151) plane in the composite beside enhancement of the composite electrical conductivity (1.66 × 10–7 Ω−1 cm−1) helps the facile nitroarenes adsorption and hydrogenation. Transient photocurrent response and linear sweep voltammetry results prove the facilitation of photogenerated charge carriers separation and transport via improving electron lifetime and lessening recombination rate. The composite photocatalyst produced higher amounts of H2 production, when inserted in a typical reaction medium containing NaBH4, comprised of 470 µ mole/g exceeding those of the counterparts (35 µ mole/g). This photocatalyst is strikingly hydrogenated 4-nitrophenol under mild conditions (25 °C and 0.35 MPa pressure of H2) with magnificent rate constant equal 34.9 × 10−3 min−1 with 100% selectivity towards 4-aminophenol.

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.

Effect of cetyltrimethylammonium bromide on the electrochemiluminiscence and electrooxidation of luminol

1983 ◽  
Vol 48 (2) ◽  
pp. 477-483 ◽  
Author(s):  
Jan Lasovský ◽  
František Grambal
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Linear Sweep Voltammetry ◽  
Critical Micellar Concentration ◽  
Peak Height ◽  
Anodic Peak ◽  
Alkaline Solutions ◽  
Platinum Electrodes ◽  
Micellar Solutions ◽  
Linear Sweep ◽  
Low Concentrations

The electrooxidation of luminol in alkaline solutions in the presence of cetyltrimethylammonium bromide (I) was studied by linear sweep voltammetry on fixed and vibrating platinum electrodes. The presence of I in low concentrations (below the critical micellar concentration) brings about aggregation of the luminol, which is manifested by an increase in the anodic peak height and its shift towards lower potentials. In micellar solutions the peak height decreases owing to the slower diffusion of the bulkier micelles, the shift to lower potentials being preserved. The light-voltage curves correspond with the voltammetric curves, exhibiting identical shifts of the peak potentials in dependence on the concentration of the surfactant.

scholarly journals Electrochemical Approaches for Rapid Characterization of Oxidizable Compounds in Different Oak Alternatives

Beverages ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Jéremie Wirth ◽  
Davide Slaghenaufi ◽  
Stéphane Vidal ◽  
Maurizio Ugliano
Keyword(s):  
Linear Sweep Voltammetry ◽  
Wine Industry ◽  
Wine Aroma ◽  
Total Current ◽  
Strong Correlations ◽  
Tannin Content ◽  
Linear Sweep ◽  
Antioxidant Characteristics ◽  
Rapid Characterization

Oak alternatives (OAs) such as chips, granulates or staves, are becoming increasingly used in the wine industry. Although they are mostly considered for their contribution to wine aroma, they are also a source of phenolic compounds to be released in the wine, in particular ellagitannins contributing to wine mouthfeel and antioxidant characteristics. In the present study, we explore the potential for a rapid analytical method based on linear sweep voltammetry (LSV) combined with disposable sensors to provide a rapid measure of the oxidizable compounds present in different OAs, as well as their characterization. Strong correlations were found between the tannin content of different OAs and the total current measures during LSV analysis, allowing a rapid quantification of the oxidizable compounds present, mostly ellagitannin. Application of derivatization to raw voltammograms allowed extraction of a number of features that can be used for classification purposes, in particular with respect to OAs types (chips or staves) and degree of toasting.

The cathodic reduction of PbO in the passive layer on lead in aqueous sulphuric acid

1984 ◽  
Vol 62 (3) ◽  
pp. 596-600 ◽  
Author(s):  
R. G. Barradas ◽  
D. S. Nadezhdin
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Reference Electrode ◽  
Linear Sweep Voltammetry ◽  
Passive Layer ◽  
Cathodic Reduction ◽  
Linear Sweep ◽  
Current Time ◽  
Lead Monoxide ◽  
Two Peaks

The cathodic reduction of the lead monoxide layer formed on lead in 30% aqueous H2SO4 under anodic oxidation at 0.6 V (vs. Hg/HgSO4 reference electrode) was investigated by linear sweep voltammetry, potential step and admittance measurements. The experimental data were analyzed respectively in terms of thin-layer electrochemistry, electrocrystallisation, and changes of resistance of the PbO layer under reduction. The results seem to be best interpreted from the theory of three-dimensional electrocrystallisation as PbO is reduced to Pb. At sub-zero temperatures the PbO peak observed on our voltammograms and potentiostatic current time transients reveals the splitting of the curves into two peaks, which may be a result of reduction of the same material but of different phases, namely, orthorhombic and tetragonal PbO.

scholarly journals From Waste to Valuable Resource: Lignin as a Sustainable Anti-Corrosion Coating

Coatings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 454 ◽  
Author(s):  
Arman Dastpak ◽  
Kirsi Yliniemi ◽  
Mariana de Oliveira Monteiro ◽  
Sarah Höhn ◽  
Sannakaisa Virtanen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Steel Corrosion ◽  
Linear Sweep Voltammetry ◽  
Corrosion Current ◽  
Polymer Coatings ◽  
Open Circuit ◽  
Linear Sweep ◽  
Cyclic Potentiodynamic Polarization

In this study, a waste of biorefinery—lignin—is investigated as an anticorrosion coating on stainless steel. Corrosion behavior of two lignin types (hardwood beech and softwood spruce) was studied by electrochemical measurements (linear sweep voltammetry, open circuit potential, potentiostatic polarization, cyclic potentiodynamic polarization, and electrochemical impedance measurements) during exposure to simulated body fluid (SBF) or phosphate buffer (PBS). Results from linear sweep voltammetry of lignin-coated samples, in particular, demonstrated a reduction in corrosion current density between 1 and 3 orders of magnitude cf. blank stainless steel. Furthermore, results from cross cut adhesion tests on lignin-coated samples demonstrated that the best possible adhesion (grade 0) of ISO 2409 standard was achieved for the investigated novel coatings. Such findings suggest that lignin materials could transform the field of organic coatings towards more sustainable alternatives by replacing non-renewable polymer coatings.

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