scholarly journals Photoelectrochemical Performance of Smooth TiO2Nanotube Arrays: Effect of Anodization Temperature and Cleaning Methods

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Chin Wei Lai ◽  
Srimala Sreekantan
Keyword(s):  
Wall Thickness ◽  
High Efficiency ◽  
Charge Transfer Resistance ◽  
Nanotube Arrays ◽  
Photoelectrochemical Performance ◽  
Transfer Resistance ◽  
Self Organized ◽  
Different Temperatures ◽  
Cleaning Methods ◽  
Low Charge

The formation of self-organized titanium dioxide (TiO2) nanotube arrays without bundling or clustering is essential for their high efficiency in photoelectrochemical (PEC) application. The present paper reports on the use of different temperatures to control the specific architecture of nanotube arrays and effective cleaning techniques to ensure the formation of clean TiO2nanotube surface. The wall thickness of nanotube arrays could be controlled from 12.5 nm to 37.5 nm through different anodization temperature ranging from 10°C to 80°C. Furthermore, ultrasonic cleaning combined with acetone showed the high-ordered TiO2nanotube arrays without morphological disorder, bundling, and microcrack problems. Based on the results obtained, a higher PEC response of 1 mA/cm2and a photoconversion efficiency of 1.3% could be achieved using a wall thickness of 12.5 nm and defect-free TiO2nanotube arrays for low charge transfer resistance.

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 Indium Tin-Oxide Wrapped 3D rGO and TiO2 Composites: Development, Characterization, and Enhancing Photocatalytic Activity for Methylene Blue

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 848
Author(s):  
Cheng Gong ◽  
Shiyin Xu ◽  
Peng Xiao ◽  
Feifan Liu ◽  
Yunhui Xu ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
3D Structure ◽  
Charge Transfer Resistance ◽  
Layer By Layer ◽  
Transfer Resistance ◽  
Photodegradation Rate ◽  
Reduced Graphene ◽  
Low Charge

A hybrid material of indium tin-oxide (ITO) wrapped titanium dioxide and reduced graphene oxide (ITO-rGO and TiO2) was prepared using a facile hydrothermal technique. TiO2 nanorods were in situ grown on the surface of rGO (rGO and TiO2), and which was then assembled onto ITO substrate layer by layer with formation of a 3D structure. ITO-rGO and TiO2 exhibit low charge transfer resistance at the electrode-electrolyte interface and have good photoresponsive ability. Methylene blue (MB) can be effectively adsorbed and enriched onto ITO-rGO and TiO2 surface. The adsorption kinetics and thermodynamics of ITO-rGO and TiO2 were evaluated, showing that the exothermic and entropy-driven reaction were the main thermodynamic processes, and the Langmuir isotherm was the ideal model for adsorption fitting. Meanwhile, ITO greatly improved degradation of rGO and TiO2 because electrons can be collected by ITO before recombination and MB can easily enter into the 3D structure of rGO and TiO2. The highest photodegradation rate of MB reached 93.40% for ITO-rGO and TiO2 at pH 9. Additionally, ITO-rGO and TiO2 successfully solved the problems of being difficult to recycle and causing secondary pollution of traditional TiO2 catalysts. Therefore, ITO-rGO and TiO2 may be a potential photocatalyst for degrading organic pollutants in water.

An in situ polymerized PEDOT/Fe3O4 composite as a Pt-free counter electrode for highly efficient dye sensitized solar cells

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1637-1643 ◽  
Author(s):  
Min Zheng ◽  
Jinghao Huo ◽  
Yongguang Tu ◽  
Jinbiao Jia ◽  
Jihuai Wu ◽  
...  
Keyword(s):  
Counter Electrode ◽  
Dye Sensitized Solar Cells ◽  
Charge Transfer Resistance ◽  
High Power Conversion Efficiency ◽  
Transfer Resistance ◽  
Dye Sensitized ◽  
Large Active Area ◽  
Low Charge ◽  
Sensitized Solar Cells

PEDOT/Fe3O4 hybrid is in situ polymerized and used as Pt-free counter electrode in dye-sensitized solar cell. Owing to large active area and low charge transfer resistance for the hybrid, the cell achieves a high power conversion efficiency of 8.69%.

scholarly journals Recycling of Expired Ceftamil Drug as Additive in the Copper and Nickel Electrodeposition from Acid Baths

2021 ◽  
Vol 18 (18) ◽  
pp. 9476
Author(s):  
Delia-Andrada Duca ◽  
Mircea Laurențiu Dan ◽  
Nicolae Vaszilcsin
Keyword(s):  
Organic Molecules ◽  
Electrochemical Impedance ◽  
Electrolyte Solutions ◽  
Optical Microscope ◽  
Charge Transfer Resistance ◽  
Favorable Effect ◽  
Transfer Resistance ◽  
Nickel Electrodeposition ◽  
Nickel Electroplating ◽  
Different Temperatures

Due to the large quantity of expired and unused drugs worldwide, pharmaceutical disposal has become a serious problem that requires increased attention. In the present paper, the study on recycling ceftazidime (CZ) as an additive in copper and nickel electrodeposition from acid baths is highlighted. CZ is the active substance from expired commercial drug Ceftamil®. Its electrochemical behavior was studied by cyclic voltammetry. As well, kinetic parameters for copper and nickel electrodeposition were determined using Tafel plots method at different temperatures and CZ concentrations in these acid baths. The activation energy was calculated from Arrhenius plots. Electrochemical impedance spectroscopy was used to investigate the charge transfer resistance and coverage degree in the electrolyte solutions at several potential values. Gibbs free energy values, calculated from Langmuir adsorption isotherms, revealed the chemical nature of CZ–electrode surface interactions. The favorable effect of the organic molecules added in copper and nickel electroplating baths was emphasized by optical microscope images. The morphology of the obtained deposits without and with 10−4 mol L−1 CZ was compared. The experimental results revealed that expired Ceftamil® is suitable as additive in copper and nickel electroplating processes from acid baths.

scholarly journals Synthesis of MoIn2S4@CNTs Composite Counter Electrode for Dye-Sensitized Solar Cells

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Gentian Yue ◽  
Renzhi Cheng ◽  
Xueman Gao ◽  
Leqing Fan ◽  
Yangfan Mao ◽  
...  
Keyword(s):  
Counter Electrode ◽  
Electrochemical Impedance ◽  
Dye Sensitized Solar Cells ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
One Step ◽  
Low Charge ◽  
Adsorption Desorption ◽  
Sensitized Solar Cells

Abstract A ternary and composite MoIn2S4@CNTs counter electrode (CE) with a hedgehog ball structure was synthesized by using a facile one-step hydrothermal method. The composite MoIn2S4@CNTs film possesses large specific surface area through N2 adsorption-desorption isotherms test, which is advantageous to adsorb more electrolyte and provide larger active contact area for the electrode. In addition, the composite MoIn2S4@CNTs CE exhibits low charge transfer resistance and fine electrocatalytic ability made from a series of electrochemical tests including cyclic voltammetry, electrochemical impedance, and Tafel curves. Under optimal conditions, the DSSC based on the MoIn2S4@CNTs-2 composite CE achieves an impressive power conversion efficiency as high as 8.38%, which remarkably exceeds that of the DSSCs with the MoIn2S4 CE (7.44%) and the Pt electrode (8.01%). The current work provides a simplified preparation process for the DSSCs.

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.

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