Understanding the effect of annealing temperature on crystalline structure, morphology, and photocatalytic activity of silver-loaded TiO2 nanotubes (original) (raw)
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Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2018
In this study, a nanocomposite of silver loaded on TiO 2 nanotubes (Ag/TNTs) was synthesized by a gamma irradiation method with a 92.42% yield. The optimized scale for Ag/TNT synthesis was 1.29 g of precursors per 100 mL solvent. The morphology and crystal structure of the Ag/TNTs were determined by transmission electron microscopy and X-ray diffraction, respectively. The Ag weight percentage in Ag/TNTs was analyzed by inductively coupled plasma atomic emission spectrometry. The results showed that the size of silver nanoparticles on the TNTs decreased when the precursor weight decreased. The Ag/TNT nanocomposite removed 95.45% of methylene blue under simulated sunlight irradiation and could be reused five times with an almost unchanged activity. The formation mechanism of silver nanoparticles on TNTs is also discussed.
Effects of the silver nanodots on the photocatalytic activity of mixed-phase TiO 2
Journal of the American Ceramic Society, 2022
We present the synthesis and photocatalytic properties of mixed- phase TiO2 nanoparticles decorated with silver nanodots obtained by environmental- friendly wet chemical method using low molecular weight chitosan as the silver reducing agent. Structural analysis of synthesized Ag nanoparticles revealed that they crystallized in a rare hexagonal modification. High- resolution transmission electron microscopy study shows that <3- nm hexagonal- Ag nanoparticles are implanted on the surface of <20- nm anatase grains. Compared to Ag- free TiO2 powders, implantation with Ag results in important increase in visible light absorption. The photocatalytic activity of the samples was measured by monitoring decolorization of concentrated textile dye solution (50 mg L−1 of Reactive Orange 16) under simulated solar irradiation of 280 W m−2. The optimum photocatalytic properties are achieved with 5 wt% of silver. Based on the collected results, the operating mechanism of the degradation process is suggested, and the effects of the silver addition are explained.
Catalysts
Arrays of titania nanotubes (TiO2NTs) were developed by electrochemical anodization and doped with silver on their surface by photodeposition to achieve TiO2NTs/Ag. It is found that only anatase TiO2NTs were formed, with the preferential growth direction perpendicular to the titanium substrate, and with the length and diameter of ~2 µm and 90–120 nm, respectively. The presence of Ag on the surface of TiO2NTs was also confirmed. The TiO2NTs and TiO2NTs/Ag were used as photocatalysts to decolorize the methylene blue (MB) aqueous solution. The photodegradation efficiency (PDE) is as high as 83% for TiO2NTs and 98% for TiO2NTs/Ag photocatalysts. This work focused on the investigation of the stability and recyclability of these photocatalysts in terms of efficiency and its physical origin by surface analysis using X-ray photoelectron spectroscopy (XPS). It is found that PDE diminishes from 83% to 76% in TiO2NTs upon eight recycling runs and from 98% to 80% in TiO2NTs/Ag upon six recyclin...
Photocatalytic degradation in silver doped TiO 2
Springer Publication, 2019
Many intriguing ways have been identified to mitigate the low photocatalytic activity of Titanium dioxide (TiO 2). One of the ways is to adulterate the structure of TiO 2 with foreign substances like metals i.e., Ni 2? , Zn 2? , Cr 3? and Fe 3? , which are having similar radii with Ti 4?. In this study, the introduction of silver into the structure of TiO 2 by Liquid Impregnation (LI) method with various mole fractions have been presented. Comparison has been made to degrade one model pollutant: Direct Blue 71 (DB71) by using both doped and undoped TiO 2. Study was further supported by studying the Langmuir and Freundlich isotherms. Enhancement in the photocatalytic degradation of the dye was observed with silver doped TiO 2 at 2.0% mole fraction as compared to undoped TiO 2. While studying the photoctalytic activity, the reaction mixture pH was kept unchanged with doped TiO 2 , wherein with undoped TiO 2 demanded acidic pH to have more photocatalytic activity.
New Journal of Chemistry, 2013
Silver decorated TiO 2 nanotube arrays (TNTAs) show great potential applications for photocatalysis and gas sensors. In this work, we report an improved strategy to modify the morphology of flow-through TiO 2 nanotube arrays (f-TNTAs) for homogeneous Ag nanoparticle loading, and their photocatalytic activities are also investigated. Firstly, TNTAs were fabricated by potentiostatic anodization in fluoridecontaining electrolytes. Subsequently, a high voltage was immediately exerted, and then a low potential was applied at the end of anodization process. The as-prepared f-TNTAs with improved bottom morphologies were finally obtained. This new kind of support was immersed in AgNO 3 solution, and then the absorbed silver ions were reduced to metallic Ag 0 by UV light. Compared with conventional TiO 2 nanotube arrays (c-TNTAs), the modified f-TNTAs show a better ability for the dispersion of Ag nanoparticles (Ag NPs) in different regions (upper, central and bottom region) of the nanotubes. A series of testing measures (XPS, EDX, SEM and XRD) were adopted to confirm this facile process. Ag decorated f-TNTAs were used as photocatalysts for the degradation of Methyl Orange (MO) under UV light. The degradation rate could reach 54% in 10 min, and the complete degradation of MO was observed after 30 min. These results were much better than that of Ag decorated c-TNTAs. The modified f-TNTAs via our method can also be used to couple with other noble metals or compound semiconductors. These composite structures are expected to find potential applications in photoelectric devices, gas sensors, and photocatalysis. † Electronic supplementary information (ESI) available: SEM images of the bottom morphology of f-TNTAs. SEM and EDX results of silver decorated c-TNTAs. SEM images of silver decorated f-TNTAs with immersing for 1 h. Absorption spectra of MO with addition of different catalysis under UV light.
Structural, morphological and photocatalytic properties of nanostructured TiO2/AgI photocatalyst
Фізика і хімія твердого тіла, 2023
Nanostructured TiO2/AgI photocatalyst under the action of ultraviolet or visible electromagnetic radiation effectively neutralizes organic pollutants in the aqueous environment. It is a nanostructure in which micro-and small mesopores of anatase TiO2 are filled with silver iodide in the superionic state. The content of the α-AgI ionconducting phase in the volume of ТіО2 pores can be ~20 wt %. To obtain a photocatalyst, titanium dioxide is synthesized by the sol-gel method, using a titanium aquacomplex solution [Ti(OH2)6] 3+ •3Cland a Na2CО3 modifier additive as a precursor. The modifying additive during synthesis ensures the fixation of =О2СО carbonate groups on the surface of oxide material particles. The presence of these groups leads to an increase in both the pore volume and the specific surface area of ТіО2. The specific surface area of carbonized titanium dioxide is 368 m 2 •g-1 , the pore volume is 0.28 cm 3 •g-1 , and their size is 0.9-4.5 nm. To fill the micro-and small mesopores of TiO2 with the superionic α-AgI phase, Ag + cations are first adsorbed from the AgNO3 solution on the titanium dioxide surface, and then the oxide material is contacted with the KI solution. Compared to the Evonik P25-TiO2 photocatalyst, the nanostructured TiO2/AgI photocatalyst demonstrates a significantly higher efficiency of photodegradation of organic dyes Congo Red and Methyl Orange in visible and ultraviolet radiation. The most active ТіО2/40AgI sample achieved complete degradation of the CR dye (5 mg/L) in 6 minutes of UV irradiation (λ = 365 nm), while the efficiency of commercial Р25-TiO2 over the same time was only 42%.
j o u r n a l h o m e p a g e Hw w w . m i n p r o c . p w r . w r o c . p l / j o u r n a l / Photocatalytic activity of Ag/TiO2 composites obtained by photoreduction treatment (PRT) was investigated. The composite materials, containing 1.0 and 2.1 wt% of silver nanoparticles were obtained by depositing silver on the Evonic–Degussa P25 titania surface. Ag/TiO2 samples were examined by SEM, XPS and BET techniques. The XPS measurements revealed that silver particles were obtained mainly in metallic form. The photocatalytic activity of pure P25 and Ag/TiO2 composites was compared in photooxidation reaction of some model compound like: formic acid (FA), rhodamine B (RhB) and methylene blue (MB). Photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that small amount of silver nanoparticles deposited on titania surface triggers the increase in photo...
Enhancement in the photocatalytic activity of Ag loaded N-doped TiO2 nanocomposite under sunlight
Journal of Materials Science: Materials in Electronics, 2014
A N-doped titania-silver nanocomposites have been prepared by simple microwave assisted and impregnation-reduction method for the first time. As synthesized nanocomposites with different Ag contents were characterized for their phase purity, morphology, particle size, optical properties and elemental composition. It is found that N-doped TiO 2 silver nanocomposites are pure in anatase phase with an average crystallite size of 10 nm. The catalyst was tested for dye degradation and photodegradation efficiency was found to be 99.6 and 88.7 % within 90 min under UV and sunlight respectively. A 40 % enhancement in the photodegradation efficiency was achieved by Ag loading in comparison with the N-TiO 2 under sunlight. The fluorescence quenching of Ag loaded N-TiO 2 indicates decrease in rate of electron-hole pair recombination that enhances photocatalytic performance. The effects of photocatalytic operational parameters such as method of surface modification, catalyst loading and irradiation sources on the photodegradation of methyl orange were also investigated.
Applied Surface Science, 2008
TiO 2 sol-gels with various Ag/TiO 2 molar ratios from 0 to 0.9% were used to fabricate silver-modified nano-structured TiO 2 thin films using a layer-by-layer dip-coating (LLDC) technique. This technique allows obtaining TiO 2 nano-structured thin films with a silver hierarchical configuration. The coating of pure TiO 2 sol-gel and Ag-modified sol-gel was marked as T and A, respectively. According to the coating order and the nature of the TiO 2 sol-gel, four types of the TiO 2 thin films were constructed, and marked as AT (bottom layer was Ag modified, surface layer was pure TiO 2 ), TA (bottom layer was pure TiO 2 , surface layer was Ag modified), TT (pure TiO 2 thin film) and AA (TiO 2 thin film was uniformly Ag modified). These thin films were characterized by means of linear sweep voltammetry (LSV), X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy and transient photocurrent (I ph ). LSV confirmed the existence of Ag 0 state in the TiO 2 thin film. SEM and XRD experiments indicated that the sizes of the TiO 2 nanoparticles of the resulting films were in the order of TT > AT > TA > AA, suggesting the gradient Ag distribution in the films. The SEM and XRD results also confirmed that Ag had an inhibition effect on the size growth of anatase nanoparticles. Photocatalytic activities of the resulting thin films were also evaluated in the photocatalytic degradation process of methyl orange. The preliminary results demonstrated the sequence of the photocatalytic activity of the resulting films was AT > TA > AA > TT. This suggested that the silver hierarchical configuration can be used to improve the photocatalytic activity of TiO 2 thin film. #
Photocatalytic activity of TiO 2 nanotube layers coated with Ag and Pt
Advances in Applied Ceramics, 2010
Ag and Au nanoparticles were found to significantly enhance the photocatalytic activity of self-organized TiO 2 nanotubular structures. The catalyst systems are demonstrated to be highly efficient for the UV-light induced photocatalytic decomposition of a model organic pollutant -Acid Orange 7. The metallic nanoparticles with a diameter of 10±2nm(Ag)and10 ± 2 nm (Ag) and 10±2nm(Ag)and28 ± 3 nm (Au) were attached to a nanotubular TiO 2 layer that consists of individual tubes of 100nmofdiameter,100 nm of diameter, 100nmofdiameter,2 lm in length and approx. 15 nm of wall thickness. Both metal particle catalyst systems enhance the photocatalytic decomposition significantly more on the nanotubes support than placed on a compact TiO 2 surface.