Electrochemical Assessment of X70 Steel With Non-Conventional Heat Treatment

ABSTRACTCorrosion behavior of an API X70 steel by potentiodynamic polarization curves was carried out. X70 steel was heat treated at a temperature of 1050°C (onset temperature solution of niobium carbonitrides) for 15 and 30 minutes hold followed by quenching in water. Test solutions for electrochemical evaluation were NS4 solution and congenital water (CW) to assess external and internal corrosion pipelines respectively. The polarization curves were performed within a range of -500mV to 1000mV for NS4 solution and the -500mV to 600mV by congenital water respect to open circuit potential (OCP) at a scan rate of 1mV/s. The tests were conducted at room temperature. The surfaces of the samples were observed by scanning electron microscope (SEM). A localized corrosion type was observed. According to polarization curves it can be observed that oxidation reaction in the anodic branch belongs to a charge transfer process. Cathodic branches reveal a process where the charge transfer resistance is influenced by a process of mass transfer. The non-conventional heat treatment improved the corrosion resistance compared to as received material.

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

Catalysts ◽

10.3390/catal10060717 ◽

2020 ◽

Vol 10 (6) ◽

pp. 717 ◽

Cited By ~ 2

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.

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Organic Dyes Containing Coplanar Dihexyl-Substituted Dithienosilole Groups for Efficient Dye-Sensitised Solar Cells

International Journal of Photoenergy ◽

10.1155/2017/7594869 ◽

2017 ◽

Vol 2017 ◽

pp. 1-14 ◽

Cited By ~ 4

Author(s):

Ciaran Lyons ◽

Neelima Rathi ◽

Pratibha Dev ◽

Owen Byrne ◽

Praveen K. Surolia ◽

...

Keyword(s):

Solar Cells ◽

Charge Transfer ◽

Density Functional ◽

Organic Dyes ◽

Intermediate Frequency ◽

Charge Transfer Resistance ◽

Open Circuit ◽

Ethanol Solution ◽

Recombination Rates ◽

Transfer Resistance

A chromophore containing a coplanar dihexyl-substituted dithienosilole (CL1) synthesised for use in dye-sensitised solar cells displayed an energy conversion efficiency of 6.90% under AM 1.5 sunlight irradiation. The new sensitiser showed a similar fill factor and open-circuit voltage when compared with N719. Impedance measurements showed that, in the dark, the charge-transfer resistance of a cell using CL1 in the intermediate-frequency region was higher compared to N719 (69.8 versus 41.3 Ω). Under illumination at AM 1.5G-simulated conditions, the charge-transfer resistances were comparable, indicative of similar recombination rates by the oxidised form of the redox couple. The dye showed instability in ethanol solution, but excellent stability when attached to TiO2. Classical molecular dynamics indicated that interactions between ethanol and the dye are likely to reduce the stability of CL1 in solution form. Time-dependent density functional theory studies were performed to ascertain the absorption spectrum of the dye and assess the contribution of various transitions to optical excitation, which showed good agreement with experimental results.

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

International Journal of Photoenergy ◽

10.1155/2019/5737952 ◽

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.

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

Metals ◽

10.3390/met12010098 ◽

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.

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Dependence on the parameters of the equivalent electrical circuit model with the thickness of viologen-based electrochromic mixture on glass substrate devices

MRS Proceedings ◽

10.1557/opl.2011.1305 ◽

2011 ◽

Vol 1328 ◽

Author(s):

David Barrios ◽

Ricardo Vergaz ◽

Juan Carlos Torres ◽

José-Manuel Sánchez-Pena ◽

Ana Viñuales ◽

...

Keyword(s):

Equivalent Circuit Model ◽

Process Variations ◽

Impedance Analysis ◽

Charge Transfer Resistance ◽

Open Circuit ◽

Electrical Circuit ◽

Circuit Model ◽

Electrical Equivalent Circuit ◽

Transfer Resistance ◽

A Charge

ABSTRACTSeveral viologen electrochromic devices with different thicknesses on glass substrates were constructed, using a mixture of 4,4’-bipyridine and 1-bromoethane. The thickness of each device was fixed using a thermoplastic spacer. The devices were electrochemically tested with optical and impedance analysis. The range of the transmittance change is highly dependent on thickness. The electrical behavior of the material and the physical and chemical characteristics are derived from the proposed electrical equivalent circuit model. A simple Randles circuit including a Warburg diffusion impedance element, a charge transfer resistance and a double layer capacitive element is proposed for the fittings process. Variations on thickness of internal layer of devices lead to use a short or an open circuit Warburg element. A threshold potential, from which the device is colored, indicates the charge diffusion effects.

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