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

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
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.

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 Electrochemical, Structural and Morphological Characterization of Hydrothermally Fabricated Binary Palladium Alloys PdCo and PdNi

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 796
Author(s):  
Edson Meyer ◽  
Raymond Taziwa ◽  
Dorcas Mutukwa ◽  
Nyengerai Zingwe
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Binary Alloys ◽  
Dye Sensitized Solar Cells ◽  
Charge Transfer Resistance ◽  
Palladium Alloys ◽  
Transfer Resistance ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

This article details the development and characterization of binary palladium alloys synthesized via a hydrothermal process. Palladium alloys, being good redox catalysts, could potentially replace platinum in many applications such as in dye sensitized solar cells, capacitors and vehicular catalytic converters where platinum is vital for maximum productivity. A good replacement should be cheap, readily available and be able to offer comparable catalytic activity to that of platinum. As such we hereby attempt to hydrothermally fabricate and characterize binary palladium alloys PdNi and PdCo that could be ideal replacements for platinum. XRD analysis of the as-synthesized binary alloys revealed the existence of only palladium peaks at 2θ values of 40.1°, 46.7°, 68.1°, 82.1° and 86.6°, indicative of the successful formation of the binary alloys. SEM micrographs revealed that both alloys consisted of spherical particles with PdCo agglomerating to an extent, whereas PdNi was widely distributed, thus it could enhance electrolyte adsorption during catalytic reduction reactions. Cyclic voltammetry analysis at 50 mV∙s−1 revealed that PdNi is more electrocatalytically active with a reduction current density of 41 mA∙cm−2 compared to 18 mA∙cm−2 for PdCo. Lower charge transfer resistance from electrochemical impedance spectroscopy confirmed the superior catalytic ability of PdNi. The two palladium alloys also produced maximum specific capacitances of 68 and 27 F∙g−1 for PdNi and PdCo respectively. Analysis of the sample stability yielded coulombic efficiency retention of 98.7 and 97% for PdNi and PdCo respectively after 1000 cycles. Results obtained have shown that the palladium alloys with their low charge transfer resistance could be ideal replacements for platinum in dye sensitized solar cells. Modest specific capacitance for PdNi illustrates its potential as an electrode catalyst in capacitors.

Electrochemical Assessment of X70 Steel With Non-Conventional Heat Treatment

MRS Advances ◽  
2017 ◽  
Vol 2 (50) ◽  
pp. 2819-2829
Author(s):  
L. R. Jacobo ◽  
R. García ◽  
V.H. López ◽  
A. Contreras
Keyword(s):  
Heat Treatment ◽  
Charge Transfer ◽  
Charge Transfer Resistance ◽  
Open Circuit ◽  
Polarization Curves ◽  
Localized Corrosion ◽  
Transfer Resistance ◽  
Internal Corrosion ◽  
Conventional Heat Treatment ◽  
A Charge

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.

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.

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 Dye-Sensitized Solar Cells Using Mesocarbon Microbead-Based Counter Electrodes

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Chien-Te Hsieh ◽  
Bing-Hao Yang ◽  
Wei-Yu Chen
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Dye Sensitized Solar Cells ◽  
Charge Transfer Resistance ◽  
Counter Electrodes ◽  
Transfer Resistance ◽  
Dye Sensitized ◽  
Catalytic Sites ◽  
Low Charge ◽  
Sensitized Solar Cells

The dye-sensitized solar cells (DSCs) equipped with mesocarbon microbead (MCMB)-based counter electrodes were explored to examine their cell performance. Three types of nanosized additives including platinum, carbon nanotubes (CNTs), and carbon black (CB) are well dispersed and coated over microscaled MCMB powders. In the design of the counter electrodes, the MCMB graphite offers an excellent medium that allows charge transfer from the ITO substrate to the dye molecule. The active materials such as Pt, CNT, and nanosize CB act as an active site provider for the redox reaction. Among these counter electrodes, the DSCs fabricated with CB electrode exhibit the highest power conversion efficiency. This improved efficiency can be attributed to the fact that the CB nanoparticles not only offer a large number of catalytic sites but also low charge transfer resistance, facilitating a rapid reaction kinetics. Such design of carbon counter electrode has been confirmed to be a promising candidate for replacing Pt electrodes.

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