Effect of pyrite on the electrochemical behavior of chalcopyrite at different potentials in pH 1.8 H2SO4

2019 ◽  
Vol 43 (11-12) ◽  
pp. 493-502
Author(s):  
Qingyou Liu ◽  
Shuai Wang ◽  
Miao Chen ◽  
Yi Yang
Keyword(s):  
Electrochemical Impedance ◽  
Saturated Calomel Electrode ◽  
Surface Characteristics ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Electrochemical Dissolution ◽  
Passive Region ◽  
Transfer Resistance ◽  
Electrochemical Behaviors ◽  
Passive Resistance

Chalcopyrite is the most abundant, but also one of the most refractory, copper sources. One way to enhance chalcopyrite’s electrochemical dissolution is by mixing it with pyrite. To understand how and to what extent pyrite affects chalcopyrite’s electrochemical dissolution at different potentials, the electrochemical behaviors of chalcopyrite, pyrite, and chalcopyrite–pyrite couples in pH 1.8 H2SO4 were studied by potentiodynamic and electrochemical impedance spectroscopy. Potentiodynamic curves showed their different electrochemical reaction states and electrode surface characteristics. From open-circuit potential to 470 mV (vs saturated calomel electrode), chalcopyrite–pyrite was passivated with Cu1− xFe1− yS2 [Formula: see text]; from 470 to 580 mV, trans-passive dissolution occurred, and in the passive region, Cu1− xFe1− yS2 transformed into Cu1− x− zS2; from 580 to 700 mV was an active region; and a pseudo-passive region was formed with CuS when the potential was above 700 mV. The smaller charge transfer resistance and passive resistance, as well as the smaller inductive relaxation, revealed how and to what extent the coupled pyrite accelerated the electrochemical dissolution of chalcopyrite.

scholarly journals Multi-Leg TiO2 Nanotube Photoelectrodes Modified by Platinized Cyanographene with Enhanced Photoelectrochemical Performance

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 717 ◽  
Author(s):  
Mahdi Shahrezaei ◽  
Seyyed Mohammad Hossein Hejazi ◽  
Yalavarthi Rambabu ◽  
Miroslav Vavrecka ◽  
Aristides Bakandritsos ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Recombination Rate ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Transfer Time ◽  
Photoelectrochemical Performance ◽  
Transfer Resistance ◽  
Photocurrent Spectroscopy ◽  
Photogenerated Electrons

Highly ordered multi-leg TiO2 nanotubes (MLTNTs) functionalized with platinized cyanographene are proposed as a hybrid photoelectrode for enhanced photoelectrochemical water splitting. The platinized cyanographene and cyanographene/MLTNTs composite yielded photocurrent densities 1.66 and 1.25 times higher than those of the pristine MLTNTs nanotubes, respectively. Open circuit VOC decay (VOCD), electrochemical impedance spectroscopy (EIS), and intensity-modulated photocurrent spectroscopy (IMPS) analyses were performed to study the recombination rate, charge transfer characteristics, and transfer time of photogenerated electrons, respectively. According to the VOCD and IMPS results, the addition of (platinized) cynographene decreased the recombination rate and the transfer time of photogenerated electrons by one order of magnitude. Furthermore, EIS results showed that the (platinized) cyanographene MLTNTs composite has the lowest charge transfer resistance and therefore the highest photoelectrochemical performance.

The influence of membrane electrode assembly’s pressing on PEM fuel cell’s performance

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Federico Perdomo ◽  
Matilde Abboud ◽  
Erika Teliz ◽  
Fernando Zinola ◽  
Verónica Díaz
Keyword(s):  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Membrane Electrode Assembly ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Polymeric Membrane ◽  
Membrane Electrode ◽  
Transfer Resistance ◽  
Supported Platinum Catalysts ◽  
Different Temperatures

Abstract The performance of a fuel cell depends on multiple factors, one of the most important being the preparation of the membrane electrode assembly (MEA). In the present work, MEAs constituted by gas diffuser electrodes (GDE) were pressed with carbon supported platinum catalysts. As solid electrolyte, a commercial polymeric membrane from Nafion was used, which was pressed at two GDE with loads of 5 and 1.5 mg/cm2 of catalyst at different temperatures and pressures for a fixed period of time. The assembly was characterized electrochemically using linear sweep voltammetry and electrochemical impedance spectroscopy at three different potentials. Also, the behavior when reversing the supply of hydrogen and oxygen to the GDE was studied. The results of the study showed a great dependence of the charge transfer resistance with the temperature, being secondary the dependence with the pressure in the range of temperature and pressure analyzed. Likewise, changes were observed in the open circuit potential after varying the temperature, pressure and catalyst load, hence affecting its maximum power and efficiency at that point.

Improved photovoltaic properties of nano-flake-based mesoporous dip-SILAR prepared BiOI electrochemical cell by tuning post-annealing treatment time at 100°C

2021 ◽  
Vol 06 ◽  
Author(s):  
MD Matiur Rahman ◽  
Shinya Kato ◽  
Tetsuo Soga
Keyword(s):  
Annealing Time ◽  
Treatment Time ◽  
Electrochemical Impedance ◽  
Short Circuit ◽  
Annealing Treatment ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
Transfer Resistance ◽  
Post Annealing

Background: This research article reports on the post-annealing treatment time effect on the dip-successive ionic layer adsorption and reaction (SILAR) prepared nano-flake-based mesoporous BiOI electrochemical cell's photovoltaic properties. Objective: Our study clarifies that the post-annealing time has a significant impact on the photovoltaic behavior and the nano-flake morphology. Methods: At 100°C for 90mins post-annealing treatment condition, the surface morphology converted into a connected uniform crystallized flaky structure, which improves the effective surface area and reduces the BiOI/ electrolyte charge transfer resistance confirmed via electrochemical impedance spectroscopy (EIS) analysis. Therefore, the maximum photovoltaic properties (short-circuit current density, Jsc = 1.83mA/cm2, open-circuit voltage, Voc = 0.48V and efficiency = 0.28%) have been observed. However, without annealing and beyond 90mins of post-annealing time, the film quality and crystallinity decreased as a consequence of photovoltaic properties the degraded. Results and Conclusion: So, our investigation finding is 90mins is the optimal post-annealing treatment duration for the dip-SILAR prepared nano-flake-based mesoporous BiOI electrochemical photovoltaic cell at 100°C post-annealing temperature.

scholarly journals Preparation of Nano-Ag-TiO2 Composites by Co-60 Gamma Irradiation to Enhance the Photocurrent of Dye-Sensitized Solar Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Le Thanh Nguyen Huynh ◽  
Viet Hai Le ◽  
Thanh Long Vo ◽  
Thi Kim Lan Nguyen ◽  
Quoc Hien Nguyen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Electrochemical Impedance ◽  
Dye Sensitized Solar Cells ◽  
Energy Conversion Efficiency ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Transfer Resistance ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Nano-silver-titanium dioxide (Ag-TiO2) composites were prepared from commercial TiO2 (P25, Degussa) and silver nitrate (AgNO3) by gamma Co-60 irradiation method with various initial concentrations of AgNO3. The nano-AgTiO2 composites are utilized as the photoanode for dye-sensitized solar cells (DSCs). Under full sunlight illumination (1000 W/m2, AM 1.5), the efficiency of DSCs has improved significantly despite the Ag content of below 1%. The DSC—assembled with 0.75 Ag-TiO2 (0.75% Ag) photoanode—showed that the photocurrent was significantly enhanced from 8.1 mA.cm−2 to 9.5 mA.cm−2 compared to the DSCs using bared TiO2 photoanode. The unchanged open-circuit voltage resulted in the overall energy conversion efficiency to be increased by 25% from 3.75% to 4.86%. Electrochemical impedance spectroscopy (EIS) analysis showed that the charge transfer resistance is reduced when increasing Ag content, demonstrating that the charge transfer at TiO2/dye interface was enhanced in the presence of silver nanoparticles.

scholarly journals Galvanic Corrosion Study between Tensile-Stressed and Non-Stressed Carbon Steels in Simulated Concrete Pore Solution

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 98
Author(s):  
Zheng Dong ◽  
Chuanqing Fu ◽  
Amir Poursaee
Keyword(s):  
Charge Transfer ◽  
Tensile Stress ◽  
Electrochemical Impedance ◽  
Pore Solution ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Carbon Steels ◽  
Cyclic Polarization ◽  
Transfer Resistance ◽  
Low Frequencies

The present study investigated the galvanic effect between tensile-stressed and non-stressed carbon steels, in addition to the influence of the tensile stress on the passivation and corrosion behavior of steel in a simulated concrete pore solution. Three different levels of tensile stress, ranging from elastic to plastic stress on the surface, were applied by adjusting the displacement of C-shape carbon steel rings. Different electrochemical measurements including the open circuit potential (OCP), the electrochemical impedance spectroscopy (EIS), the zero-resistance ammetry (ZRA), and the cyclic polarization were performed. Based on the results of EIS, the tensile stress degraded the resistance of the oxide film in moderate frequencies while enhancing the charge transfer resistance in low frequencies during passivation. As corrosion propagated, the stressed steel yielded a similar charge transfer resistance to or an even lower charge transfer resistance than the non-stressed steel, especially in the case of plastic tensile stress. The galvanic effect between the tensile-stressed and non-stressed steels increased the chloride threshold value of the tensile-stressed steel, although the susceptibility to pitting corrosion was exhibited after being corroded.

scholarly journals Preparation of nanoporous BiVO 4 /TiO 2 /Ti film through electrodeposition for photoelectrochemical water splitting

2018 ◽  
Vol 5 (9) ◽  
pp. 180728 ◽  
Author(s):  
Dong Hongxing ◽  
Liu Qiuping ◽  
He Yuehui
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Saturated Calomel Electrode ◽  
Photocurrent Density ◽  
Charge Transfer Resistance ◽  
Photoelectrochemical Properties ◽  
Photocatalytic Efficiency ◽  
Transfer Resistance ◽  
Electrodeposition Time ◽  
Absorption Studies

A nanoporous BiVO 4 /TiO 2 /Ti film was successfully fabricated by electrodepositing a nanoporous BiOI film on nanoporous TiO 2 arrays followed by annealing at 450°C for 2 h. The electrodeposition of BiOI film was carried out at different times (10, 30, 100, 500 and 1000 s) in Bi(NO 3 ) 3 and KI solution. The morphological, crystallographic and photoelectrochemical properties of the prepared BiVO 4 /TiO 2 /Ti heterojunction film were examined by using different characterization techniques. UV–vis spectrum absorption studies confirmed an increase in absorption intensities with increasing electrodeposition time, and the band gap of BiVO 4 /TiO 2 /Ti film is lower than that of TiO 2 /Ti. The photocatalytic efficiency of BiVO 4 /TiO 2 /Ti heterojunction film was higher compared to that of the TiO 2 /Ti film owing to the longer transient decay time for BiVO 4 /TiO 2 /Ti film (3.2 s) than that of TiO 2 /Ti film (0.95 s) in our experiment. The BiVO 4 /TiO 2 /Ti heterojunction film prepared by electrodeposition for 1000 s followed by annealing showed a high photocurrent density of 0.3363 mA cm −2 at 0.6 V versus saturated calomel electrode. Furthermore, the lowest charge transfer resistance from electrochemical impedance spectroscopy was recorded for the BiVO 4 /TiO 2 /Ti film (1000 s) under irradiation.

scholarly journals A Combinatorial Electrochemical Biosensor for Sweat Biomarker Benchmarking

2019 ◽  
Vol 25 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Antra Ganguly ◽  
Paul Rice ◽  
Kai-Chun Lin ◽  
Sriram Muthukumar ◽  
Shalini Prasad
Keyword(s):  
Electrochemical Sensors ◽  
Electrochemical Impedance ◽  
Flexible Substrate ◽  
Chloride Ion ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Label Free ◽  
Transfer Resistance ◽  
Disease Biomarker ◽  
Sweat Chloride

Misclassification of an acute disease condition as chronic and vice versa by electrochemical sweat biomarker sensors can cause significant psychological, emotional, and financial stress among patients. To achieve higher accuracy in distinguishing between a chronic condition and an acute condition, there is a need to establish a reference biomarker to index the actual chronic disease biomarker of interest by combinatorial sensing. This work provides the first technological proof of leveraging the chloride ion content in sweat for a combinatorial sweat biomarker benchmarking scheme. In this scheme, the sweat chloride ion has been demonstrated as the reference/indexing biomarker, while sweat cortisol has been studied as the disease biomarker of interest. Label-free affinity biosensing is achieved by using a two-electrode electrochemical system on a flexible substrate suitable for wearable applications. The electrochemical stability of the fabricated electrodes for biosensing applications was studied by open-circuit potential measurements. Attenuated total reflectance–Fourier transform infrared spectroscopy spectra validate the crosslinker–antibody binding chemistry. Concentration-dependent analyte–capture probe binding induces a modulation in the electrical properties (charge transfer resistance and double-layer capacitance) at the electrode–sweat buffer interface, which are transduced by nonfaradaic electrochemical impedance spectroscopy (EIS). Calibration dose responses for the sensor for cortisol (5–200 ng/mL) and chloride (10–100 mM) detection were evaluated in synthetic (pH 6) and pooled human sweat ( R2 > 0.95). The variation in the cortisol sensor response due to fluctuations in sweat chloride levels and the significance of reporting normalized biomarker levels were demonstrated to further emphasize the need for biomarker benchmarking in electrochemical sensors.

scholarly journals Electrochemical behavior for corrosion protection of mild steel (MS) in 1M HCl medium by using lidocaine drug as an inhibitor

2020 ◽  
Vol 61 (4) ◽  
pp. 286-305
Author(s):  
Ali Adel ◽  
El-Aziz Abd ◽  
Tilp Amal
Keyword(s):  
Weight Loss ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Adsorption Parameters ◽  
Transfer Resistance ◽  
Surface Examination ◽  
The Impact

The impact of Lidocaine as a save corrosion inhibitor for mild steel (MS) in 1M HCl by using weight loss (WL), Hydrogen evaluation (HE), open circuit potential (EO C P), potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) and Electrochemical frequency modulation (EFM) techniques has been investigated. Weight loss studied at various temperatures between (25-45oC) but Hydrogen evaluation and electrochemical studies at room temperature. The effect of temperature on the inhibition of corrosion has been studied and the thermodynamic activation and adsorption parameters were calculated. The morphology of MS was examined by scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX) technology and atomic force microscopy (AFM). EIS data indicate that in the presence of drug the double layer capacitance was decreased and the charge transfer resistance increased. The adsorption of the Lidocaine on MS surface was found to obey Langmuir adsorption isotherm and elucidate the mechanism of corrosion inhibition. The Lidocaine drug acts as mixed type inhibitor. All surface examination confirms the formation thin film covered the surface of the metal and prevent the surface of the metal from corrosion.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

scholarly journals Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1929
Author(s):  
Alexander Rodríguez ◽  
Francisco Burgos-Flórez ◽  
José D. Posada ◽  
Eliana Cervera ◽  
Valtencir Zucolotto ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Neuronal Damage ◽  
Charge Transfer Resistance ◽  
Single Frequency ◽  
Response Analysis ◽  
Transfer Resistance ◽  
Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

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