Effect of Anodization Duration in the TiO2 Nanotubes Formation on Ti Foil and Photoelectrochemical Properties of TiO2 Nanotubes

In this work, the effect of anodizing duration on the morphology and photoelectrochemical properties of TiO2 nanotubes arrays (NTAs) has been investigated The samples were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) to characterize their crystalline structure and compositional. Surface morphological and their dimensional variation was examined by field emission scanning electron microscopy (FESEM). The anodizing duration played a significant role in the formation of TiO2 nanotubes arrays. Moreover, the photoelectrochemical properties (PEC) were studied through photocurrent measurements. Optimum anodizing duration of 60 min at 40 V exhibited maximum photocurrent of 0.03 mA cm-2 under illumination of halogen light

Effect of Electrolyte Composition on Structural and Photoelectrochemical Properties of Titanium Dioxide Nanotube Arrays Synthesized by Anodization Technique

العمل الحالي يتضمن تأثير مكونات المحلول الالكتروليتي  [@1= 0.5 wt.%  NH4F / 5% H2O / 5% Glycerol (GLY)/ 90%  Ethylene Glycol (EG)] and [ @2= 0.5 wt. % NH4F / 5% H2O / 95%  Ethylene Glycol (EG)]. على التركيب والخصائص الكهروكيميائية الضوئية للانابيب النانوية تيتانيا. تم تحضير ركائز التيتانيا بنجاح بواسطة تقنية الانودة والتي اجريت عند 40 فولت ولمدة ساعة وفي محاليل الكتروليتية مختلفة. شخصت الخواص الكيميائية الفيزيائية لـ TNTAs باستخدام مقياس حيود الأشعة السينية (XRD) ، المجهر الإلكتروني (FESEM) ،والأشعة السينية المشتتة للطاقة (EDX) , والانعكاس الطيفي للاشعة فوق البنفسجية. تم تقييم الاستجابة الكهروضوئية ل TNTAs في(  M 0.01) Na2S  تحت ضوء متقطع من مصباح الهالوجين. لم يكن قطب TNTAs المعد في المحلول الالكتروليتي 1@  كافيًا لزيادة استجابة التيار الكهروضوئي مقارنة بـ TNTAs المعد في 2@ . أظهر القطب TNTAs المعد في حل 2@  أعلى كفاءة للتحويل الضوئي بالمقارنة مع TNTAs الأخر.The present work involves studying the effect of electrolyte composition [@1= 0.5 wt.%  NH4F / 5% H2O / 5% Glycerol (GLY)/ 90%  Ethylene Glycol (EG)] and [ @2= 0.5 wt. % NH4F / 5% H2O / 95%  Ethylene Glycol (EG)]  on the structural and photoelectrochemical properties of titania nanotubes arrays (TNTAs). TNTAs substrates were successfully carried out via anodization technique and were carried out in 40 V for one hour in different electrolytes (@1, and @2). The properties of physicochemical of TNTAs were distinguished via an X-ray Diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM), an Energy Dispersive X-ray (EDX), and UV–visible diffuse reflectance. The photoelectrochemical response of TNTAs was evaluated in 0.01M Na2S under the choppy light of a halogen lamp. TNTAs photoelectrode prepared at @1 electrolyte was not sufficient to increase the photocurrent response compared to TNTAs prepared at @2. The TNTAs photoelectrode prepared in the @2 electrolyte confirmed the highest photoconversion efficiency compared to the TNTAs photoelectrode prepared in the @1 electrolyte

Structural Characterization and Visible Light-Induced Photoelectrochemical Performance of Fe-Sensitized TiO2 Nanotube Arrays Prepared via Electrodeposition

Surface modification of TiO2 nanotube arrays via metal doping is one of the approaches to narrow the wide bandgap of TiO2 in order to increase its adsorption to the visible region. The present work focuses on the fabrication of a Fe-sensitized TiO2 nanotube arrays (Fe- TNT) photoanode. Ordered Fe-TNTs were successfully synthesized using a facile two-step electrochemical method by varying the deposition voltage (2-4 V). The morphology, structure, composition, and visible light response were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), UV-Vis diffusion reflection spectroscopy (DRS), and photoelectrochemical (PEC) test. The XRD investigation demonstrated that the sensitization of Fe did not destroy the nanotube array structure, and the Fe-TNTs had an anatase phase composed of cubic-like particles at higher deposition voltages. The UV–Vis absorption spectra of the Fe-TNTs showed a redshift of photoresponse towards visible light. Such a redshift was characterized by a decrease in bandgap energy and the photo efficiency was enhanced. The optimal photoelectrochemical performance was observed at 2.5 V deposition voltage for 10 minutes and surpassed that of pristine titania nanotube arrays. The present work demonstrates feasible modification of TiO2 with Fe as a potential photoanode in solar conversion devices

Effect of heat treatment on photoelectrochemical performance of hydrothermally synthesised Ag2S/ZnO nanorods arrays

Low temperature hydrothermal method was used to produce a large surface area ZnO NRs on conductive glass. The same method was used to fabricate a photoelectrode of Ag2S quantum dots onto the nanorod arrays. Ag2S QDs/ZnO NRAs heterostructure was employed as photoanode in a standard 3-electrodes photoelectrochemical cell. A significant enhancement in the photoelectrochemical performance was observed for the Ag2S QDs/ZnO upon heat treatment 400 °C which displayed an impressive photoconversion efficiency of 4.08% by achieving ∼10-times higher compared to bare ZnO NRAs. This enhancement was attributed to the improved morphological structure, crystallinity and optical properties of the synthesised heterostructures

Effect of hydrothermal growth time on ZnO nanorod arrays photoelectrode performance

High density and vertically aligned zinc oxide nanorod arrays (ZnO NRs) have been prepared directly on indium-doped tin oxide (ITO) substrates via two-steps preparation: sol-gel spin coating and hydrothermal process. The nanostructured ZnO was characterized for its morphology, crystalline structure and optical properties by using field emission scanning electron microscopy (FESEM), X-ray diffractometry, and ultraviolet-visible spectroscopy respectively. In addition, the photoeletrochemical (PEC) properties were investigated through photocurrent measurements. The ZnO NRs/ITO had wurtzite-structured (hexagonal) ZnO and preferred growth along (0001) direction. When the growth time was 4 h, ZnO NRs/ITO showed impressive photoresponse. The PEC analysis verified that the ZnO NRs gave better photocurrent response and photoconversion efficiency with approximately 42 times greater than seed layer

Fabrication of CdSe nanoparticles sensitized TiO2 nanotube arrays via pulse electrodeposition for photoelectrochemical application

Solar energy is an alternative sustainable energy resource that can be harvested using photoelectrochemical cell comprised of inorganic sensitized nanostructured oxide semiconductor electrode. In this work, pulse electrodeposition was used to deposit CdSe onto titanium dioxide nanotube arrays (TiO2 NTAs). TiO2 NTAs are commonly used in the nanostructured photoelectrochemical cells due to their high surface area, fewer interfacial grain boundaries and excellent charge transfer between interfaces. Duty cycle of pulse electrodeposition played an important role in the formation of CdSe nanoparticles. A significant enhancement in the photoelectrochemical performance was observed for the heterostructure of CdSe/TiO2 NTAs. CdSe/TiO2 NTAs prepared at 50% duty cycle exhibited maximum photocurrent of 1.94 mA cm−2 and photoconversion efficiency of 1.18% which was 59 times higher than bare TiO2 NTAs. These results demonstrated that significant enhancement in the photoconversion efficiency could be obtained by incorporating CdSe as sensitizer into the TiO2 nanotube arrays via pulse electrodeposition technique

Electrochemical deposition of CdSe-sensitized TiO2 nanotube arrays with enhanced photoelectrochemical performance for solar cell application

Particular interest has been given to the self-organized titania nanotube TiO2 thin films prepared by using anodisation method followed by annealing in the air, while the CdSe layer was potentiostatically electrodeposited onto the TiO2 nanotube films at various pH. The resulting films were studied by using energy dispersive X-ray spectroscopy, X-ray diffraction, field emission scanning electron microscopy, UV–Vis spectroscopy and photoelectrochemical analysis to characterize their compositional, crystalline structure, surface morphological, optical, and photoconversion efficiency characteristics. The resulting CdSe/TiO2 nanotube exhibits significant enhancement in optical absorption, photocurrent density and photoconversion efficiency. CdSe/TiO2 nanotube prepared at pH 3 exhibited the highest photocurrent density of 2.13 mA cm−2 and photoconversion efficiency of 1.02 % which is 51 times higher than TiO2 nanotube array. This may due to the formation of CdSe nanocrystals which were well crystallized and bonded with TiO2 NTAs contributing to the enhanced photoresponse and photostability of the overall performance of CdSe/TiO2 NTAs heterostructures

Hydrothermal deposition of CdS on vertically aligned ZnO nanorods for photoelectrochemical solar cell application

CdS/ZnO nanorods composite nanofilms were successfully synthesized via hydrothermal method on indium doped tin oxide glass substrates. Sequentially deposited CdS formed cauliflower like nanostructures on vertically aligned ZnO nanorods. The morphological, compositional, structural and optical properties of the films were characterized by field emission scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and ultraviolet–visible spectroscopy. Photoelectrochemical conversion efficiencies were evaluated by photocurrent measurements in a mixture of Na2S and Na2SO3 akaline aqueous solution. The amount of deposit, as well as the diameter and crystallinity of the CdS cauliflower were found to increase with growth time. CdS/ZnO nanorods composite exhibited greater photocurrent response than ZnO nanorod arrays. Besides, the composite film with 90 min of growth duration displayed the highest photocurrent density which is nearly four times greater than plain ZnO nanorods under the illumination of halogen light. The result exhibited remarkable photoconversion efficiency (η) of 1.92 %

Synthesis, Characterization and Biological Activates Studies of some New Derivatives From 2-aminoo-5-mercapto-1, 3, 4-thiadiazole

In this work, CdS/TiO2 nanotubes composite nanofilms were successfully synthesized via electrodeposition technique. TiO2 titania nanotube arrays (NTAs) are commonly used in photoelectrochemical cells as the photoelectrode due to their high surface area, excellent charge transfer between interfaces and fewer interfacial grain boundaries. The anodization technique of titanium foil was used to prepare TiO2 NTAs photoelectrode. The concentration of CdCl2 played an important role in the formation of CdS nanoparticles. Field emission scanning electron microscopy (FESEM) shows that the CdS nanoparticles were well deposited onto the outer and inner of nanotube at 40 mM of CdCl2. X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analyses were executed for the determination of the composition and crystalline structure of the synthesized samples. Furthermore, the data of EDX confirms the formation of titanium and oxygen for TiO2 nanotubes and cadmium and sulfide for CdS deposits. UV–visible diffuse reflectance spectroscopy (UV-DRS) displayed that CdS nanoparticle which deposited onto TiO2 NTAs causes a red-shift into the visible region. CdS/TiO2 NTAs sample prepared at 40 mM of CdCl2 showed maximum photocurrent of 1.745 mA cm-2 while the bare TiO2 NTAs showed 0.026 mA cm-1

Electrochemical synthesis and properties of cadmium selenide sensitised titania nanotubes for photoelectrochemical cells

Solar energy is an alternative sustainable energy resource that can be harvested using photoelectrochemical cell comprised of inorganic sensitized nanostructured oxide semiconductor electrode. In this work, the electrochemical synthesis, characteristics and photoelectrochemical performance of cadmium selenide (CdSe) sensitized titanium dioxide nanotube arrays (TiO2 NTAs) were studied. TiO2NTAs thin film electrodes were prepared by the anodisation method of titanium foil in a two electrode cell containing NH4F solution. Parameters affecting the morphology,structure and geometry of TiO2NTAs were investigated in three different electrolytic media namely the acidic aqueous solution (NH4F/H2O), mixture of aqueous/organic solution (NH4F/H2O/EG) and an organic solution (NH4F/EG). The characteristics of TiO2NTAs were examined using X-ray diffractometry (XRD), energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FESEM), Transmission Electron Microscopy (TEM) and High Resolution Transmission Electron Microscopy (HRTEM) and UV-visible diffuse reflectance spectroscopy (UV-DRS). Meanwhile, the photoelectrochemical responses of TiO2NTAs were investigated using linear sweep photovoltammetry (LSPV). Three electrochemical deposition methods were used to deposit CdSe onto TiO2NTAs by applying the potentiostatic deposition, cyclic voltammetric deposition and pulse electrodeposition methods. CdSe was electrodeposited onto TiO2NTAs from an electrolyte containing CdCl2 and SeO2with Na2SO4as the supporting electrolyte. Cyclic voltammetry was used to select the probable range of the potential for deposition which was found to be from -0.65 V to -1.00 V. Potentiostatic electrodeposition techniques has been carried out at the different potential of deposition, time of deposition, concentration of SeO2, concentration of CdCl2, pH and temperature of annealing. For pulse electrodeposition, the effect of varying deposition potential, deposition time, duty cycle, concentration of SeO2, concentration of CdCl2, pH, and temperature of annealing were studied. The effect of different potential range, scan rate, number of cycles, pH and temperature of annealing were investigated for cyclic voltammeric deposition. X-ray diffraction (XRD) patterns showed that the deposited CdSe onto TiO2NTAs were polycrystalline with hexagonal structure. The photoelectrochemical (PEC) properties of the synthesised films were evaluated using linear sweep photovoltammetry (LSPV) by illuminating the samples intermittently with a halogen lamp (120 V, 300 W) while immersing in 0.01 M Na2S electrolyte. Photocurrent was observed due to the reaction involving generated minority carriers (holes) on the electrode surface. Therefore, the deposited CdSe is an n-type semiconductor in this work. The XRD and PEC results suggested that the suitable electrolyte bath composition for CdSe deposition was 20 mM CdCl2, 5 mM SeO2, and 20 mM Na2SO4. Uniform potentiostatic deposition of CdSe onto TiO2NTAs was obtained at the potential of -0.7 V with the deposition time of 30 minutes at pH 3.0 under the annealing condition of 250 °C in N2 atmosphere for 60 minutes. Meanwhile, pulse electrodeposition involved pulse potential of -0.85 V at 20 minutes of Ton with 50% duty cycle under the annealing condition of 350 °C in N2 atmosphere for 60 minutes. Besides, cyclic voltammetric deposition was conducted at the potential range of -0.60 V to -1.00 V with the scan rate of 5 mV/s for 6 cycles at pH 3.0 under the annealing condition of 250 °C in N2 atmosphere for 60 minutes. It was found that the optical properties of CdSe/TiO2 nanotubes films have direct optical band gap energy values (Eg) in the range of 1.7 eV to 1.84 eV. The morphological property of the prepared samples was examined by field emission scanning electron microscopy (FESEM). The crystallite sizes of CdSe determined from XRD were in between 10.80 for potentiostatic technique, 15.50 nm for pulse electrode position and 7.00 nm for cyclic voltammetric deposition. The ratio of Cd:Se was 1:1 as shown in EDXenergy dispersive X-ray analysis. The photo efficiency was evaluated in 0.01 M Na2S under halogen illumination. The CdSe/TiO2 nanotubes film deposited using pulse deposition displayed the best photoefficiency (1.96%) compared to potentiostatic and cyclic voltammetric techniques