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Ag2S decorated titanium oxide nanotubes (Ag2S/NTs) were prepared by electrochemical anodizing and successive ionic layer adsorption and reaction (SILAR) approach. The prepared samples were characterized by X-ray diffraction, field emission scanning electron microscopy coupled with energy dispersive X-ray analysis and diffuse reflectance spectroscop...
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... The energy gap (Eg) of HOOC-QDs was estimated by extrapolating the linear portion of the (αhν) curve to 0 using incident photon energy (hν), as shown in Fig. 3 (c) with an estimated value of 2.34 eV. The Brus equation Eq. (7) can be used to describe the emission energy of quantum dot semiconductor nanocrystals in terms of the band gap energy E g , Planck's constant h, the radius of the quantum dot r, and the effective mass of the excited electron m e and the excited hole m h [7,41]. Eq. (7) was used to determine the size of the HOOC-QDs from its energy band gap. ...
Caffeine is the most abundant and widely consumed active medicinal compound, making it the most representative pollutant in the environment. This research involved synthesizing high-performance fluorescent HOOCC– –C-functionalized Ag2S quantum dots (HOOC-QDs) measuring approximately 4.35 nm in size using the hydrothermal method. These QDs were then used to produce fluorescent molecularly imprinted polymer nanoparticles (MIP-Ag2S NPs) measuring 20.31 nm. The MIP-Ag2S NPs were created through a graft suspension
copolymerization process involving methacrylic acid monomer, ethylene glycol dimethacrylate cross-linker, and
caffeine template molecules. The polar carboxylic acid groups enhance the interaction with the template molecules, which is crucial for selectivity, and the -C– –C- groups aid in network formation. The MIP-Ag2S NPs
emitted fluorescence at around 500 nm, which was significantly reduced after caffeine adsorption. The pHsensitive MIP-Ag2S NPs had a maximum caffeine adsorption capacity of 488 mg/g at pH 6 and a maximum
release of approximately 96% at pH 2.2. Additionally, repeated cycles of adsorption and desorption did not result
in a significant loss of adsorption capacity. The HOOC-QDs can be used to prepare MIPs for extracting and
recognizing pollutants and medicine in water and for controlled drug delivery systems.
... On the other hand, Ag is also a promising promotor for TiO2 as it is a noble metal that could reduce the recombination rate of the photogenerated electrons and holes through the formation of the Schottky Barrier on the Ag-TiO2 interface. It is also well documented that Fe-and Ag-modified TiO2 nanotubes were successfully fabricated through electrochemical anodization of Ti plates to grow nanotubular structure, which is followed by a successive ionic layer adsorption and reaction (SILAR) method to incorporate Fe and/or Ag [23][24][25][26]. Interestingly, besides being assigned as photocatalysts [23,25], Fe-and Agmodified TiO2 nanotubes fabricated via the anodization-SILAR combined methods were suitable for other applications, e.g. as electrocatalysts [24] and supercapacitors [26]. ...
... It is also well documented that Fe-and Ag-modified TiO2 nanotubes were successfully fabricated through electrochemical anodization of Ti plates to grow nanotubular structure, which is followed by a successive ionic layer adsorption and reaction (SILAR) method to incorporate Fe and/or Ag [23][24][25][26]. Interestingly, besides being assigned as photocatalysts [23,25], Fe-and Agmodified TiO2 nanotubes fabricated via the anodization-SILAR combined methods were suitable for other applications, e.g. as electrocatalysts [24] and supercapacitors [26]. Despite these virtues, nonetheless, there remain limited studies that compare Fe and Ag as promotors for TiO2 nanotubes-, especially in degrading microplastics and disinfection of E. Coli. ...
... The introduction of either Fe or Ag dopant into TiO2 nanotubes was done after anodization by a Successive Ionic Layer Adsorption and Reaction (SILAR) method [23][24][25]. The amorphous TNT was firstly immersed in a 140-mL solution of either Fe(NO3)3 (Merck) as Fe 3+ precursor or AgNO3 (Merck) as Ag + precursor under continuous stirring for 5 mins. ...
In this study, Fe- and Ag-modified TiO2 nanotubes were synthesized via an anodization method as photocatalysts for degradation of polyethylene microplastics and disinfection of Escherichia coli (E. coli). The anodization voltage, as well as the Fe3+ or Ag+ concentrations on TiO2 nanotubes were evaluated and correlated to their corresponding photocatalytic properties. TiO2 nanotubes were firstly synthesized by anodization of Ti plates in a glycerol-based electrolyte, followed by incorporation of either Fe or Ag via a Successive Ionic Layer Adsorption and Reaction (SILAR) method with Fe(NO3)3 and AgNO3 as Fe and Ag precursors, respectively. UV-Vis DRS shows that the addition of Fe or Ag on TiO2 nanotubes causes a redshift in the absorption spectra. The X-ray diffractograms indicate that, in the case of Fe-modified samples, Fe3+ was successfully incorporated into TiO2 lattice, while Ag scatters around the surface of the tubes as Ag and Ag2O nanoparticles. A microplastic degradation test was carried out for 90 mins inside a photoreactor with UVC illumination. TiO2 nanotubes that are anodized with a voltage of 30 V exhibit the best degradation results with 17.33% microplastic weight loss in 90 mins. Among the modified TiO2 nanotubes, 0.03 M Ag-TiO2 was the only one that surpassed the unmodified TiO2 in terms of microplastic degradation in the water, offering up to 18% microplastic weight loss in 90 min. In terms of E. coli disinfection, 0.03M Ag-TiO2 exhibit better performance than its unmodified counterpart, revealing 99.999% bactericidal activities in 10 mins. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
... In addition, the poor interfacial photoelectron-holes separation and transfer efficiency of these TiO 2 -based catalysts is far from the expect value on account of the weak interaction between photocatalysts particles and free N 2 molecules [20,21]. Hence, compared with the photodegradation of organic wastewater, CO 2 reduction, Photocatalytic H 2 evolution, and H 2 O 2 photosynthesis, N 2 photofixtion is more difficult [22][23][24][25][26]. The reason is that the process of N 2 fixation should take more energy to overcome the high-energy N 2 intermediates formed (such as N 2 and N 2 H) [27]. ...
Direct fixation of nitrogen (N2) to ammonia (NH3) under ambient conditions via photocatalysts is a promising method to relieve the pressure of energy shortage, where chemisorptions of torpid nitrogen and delivery of photoproduced electrons to N≡N bond are recognized technical limitations. In this work, we have developed the catalysts of NiFe-LDH-derived sulfides microspheres ([NiFe]S) with excellent photocatalytic activity for reduction of N2 to NH3. Excitingly, the NH3 generation rates of [NiFe]S catalysts reached up to 111.83 μmol·L−1·h−1 under visible light irradiation in water, which were 10.35 times than that of NiFe-LDH microspheres. The reason was due to the higher photo-induced carrier separation and transmission efficiency of [NiFe]S microspheres. In addition, the possible photocatalytic mechanism was proposed. This new work could guide the design of efficient catalysts and open up the application of metal sulfides in photocatalytic N2 fixation.
... To overcome these shortcomings, certain metal oxides are added as dopants. 3,4 To increase the photocatalytic efficiency further, hybrid photocatalysts are prepared to employ biomaterials. This hybrid photocatalyst not only increases photocatalytic activity but also acts as good antimicrobial agents. ...
In this work, WO 3-TiO 2 , chitosan-blended WO 3-TiO 2 , and garlic-loaded WO 3-TiO 2 nanocomposites were synthesized by the sol−gel and precipitation technique. The synthesized nanocomposites were characterized by XRD, FE-SEM, HR-TEM, EDX, UV-DRS, FT-IR, and TG-DTA analysis. The photocatalytic efficiency of the three synthesized nanocomposites on the degradation of dyes such as rhodamine B (Rh-B), methylene blue (MB), and methyl orange (MO) as organic pollutants was evaluated under solar light irradiation. The results show that garlic-loaded WO 3-TiO 2 nanocomposites act as an excellent photocatalyst than chitosan-blended WO 3-TiO 2 and WO 3-TiO 2 nanocomposites. Further, the antimicrobial activity of the synthesized nanocomposites was examined against Gram-negative bacteria (Escherichia coli) by the well diffusion method. Garlic-loaded WO 3-doped TiO 2 nanocomposites have demonstrated good antibacterial activity over chitosan-blended WO 3-TiO 2 nano-composites and WO 3-TiO 2 nanocomposites. The possible reason may be the presence of organic sulfur compounds in garlic.
... The variation in absorption as a function of wavelength for all the four concentrations of [Cu (x) TiO 2 (1-x) ] is shown in Figure 10. From the nature of the curve, it is noticeable that the fastest degradation [56] is found to be when x equals to 2 wt%. Reason for the fastest decay for low doping concentration, that is, 1% or 2% can be understood from the fact that when doping concentration of Cu in TiO 2 is low, Cu act as recombination center, and thus photo-activity decreases. ...
We report the fabrication and characterization of varying concentration (x) of copper (Cu)-doped TiO 2 nanocomposites [Cu (x) TiO 2(1-x) ] exploring the photocatalytic properties for sunscreen applications. The Cu-doped TiO 2 nanocomposite [Cu (x) TiO 2(1-x) ] has been synthesized by the low-temperature lab-scale sol-gel hydrothermal method. The concentration of Cu in TiO 2 has been chosen as 1%, 2%, 3%, and 4% by weight. With varying concentrations of [Cu (x) TiO 2(1-x) ], the structural and morphological properties are obtained using x-ray diffraction (XRD) and scanning electron micros-copy (SEM). The effect of optical properties for varying concentrations of Cu 2þ ions in TiO 2 has been studied using Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy. Further, by exploring the photocatalytic properties of fabricated [Cu (x) TiO 2(1-x) ] has been utilized for sunscreen applications. The concept of sunscreen application of Cu-doped TiO 2 can be viewed from the fact that the bare TiO 2 generates free radicals that can raise the risk of harmful effects on the skin. Our aim is to synthesize the nontoxic material which can either stop or slow the process of generation of free radicals under sun exposure. In the sun exposure, the risk of free radicals produces by pristine TiO 2 can be reduced by doping of copper with titania. We have been observed that [Cu (x) TiO 2(1-x) ] with x equaling 4% (rutile phase) displays the most effective UV-blocking property with weak photocatalytic activity and is found to be better for sunscreen application. Therefore, Cu-doped TiO 2 nanocomposite maintains all the properties of TiO 2 at nanoscale as well as improves the concerning property of the cosmetic industry. GRAPHICAL ABSTRACT ARTICLE HISTORY
... Since it was first reported by Fujishima, photoelectrochemical (PEC) water splitting has shown to be a renewable energy conversion technique [1]. Different metal oxide semiconductors such as SnO 2 , CeO 2 , CuO, Cu 2 O, Ta 2 O 5 , TiO 2 , ZnO, Fe 2 O 3 and WO 3 and the corresponding composites have been extensively used as photoelectrodes (photoanodes or photocathodes) in photoelectrochemical cells [2][3][4][5][6][7][8][9]. One of such oxides is titanium oxide (TiO 2 ), which has been known as an outstanding candidate photoanode in photoelectrochemical water splitting cells given its strong oxidation resistance, abundance, good stability, low cost, low toxicity, remarkable photostability and efficient photoelectrocatalytic performance [6,9]. ...
... Different metal oxide semiconductors such as SnO 2 , CeO 2 , CuO, Cu 2 O, Ta 2 O 5 , TiO 2 , ZnO, Fe 2 O 3 and WO 3 and the corresponding composites have been extensively used as photoelectrodes (photoanodes or photocathodes) in photoelectrochemical cells [2][3][4][5][6][7][8][9]. One of such oxides is titanium oxide (TiO 2 ), which has been known as an outstanding candidate photoanode in photoelectrochemical water splitting cells given its strong oxidation resistance, abundance, good stability, low cost, low toxicity, remarkable photostability and efficient photoelectrocatalytic performance [6,9]. One-dimensional TiO 2 nanostructures, especially TiO 2 nanotubes, have been of considerable interest because of their geometrical shape, optical and electrical characteristics. ...
CrTiO2 nanotube, tungsten-modified CrTiO2, iron-modified CrTiO2 and tungsten–iron-modified CrTiO2 have been prepared by facile one-step anodization coupled with chemical bath deposition method. XRD, FE-SEM, EDX mapping and UV–Vis spectroscopy were used to characterize the synthetic samples. The impacts of these compounds on the photoelectrochemical activities of modified CrTiO2 photoelectrodes have been studied. Photoelectrochemical (PEC) water splitting performance of bare CrTiO2 nanotube photoelectrodes has remarkably been increased by hybrid tungsten–iron–CrTiO2 nanotube composite photoelectrodes. Good photoelectrocatalytic and stable photoelectrochemical performance have been shown by tungsten–iron–CrTiO2 (denoted as S6). The synergistic effect of WO3, Fe2O3 and CrTiO2 can be accounted for the considerable increase in the performance of tungsten–iron-modified CrTiO2, enhancement of optical absorption in the visible region and the suitable band positions of these composites. Ultimately, the recyclability of the synthetic tungsten–iron-modified CrTiO2 photocatalysts showed the good stability of their photocatalytic activity.
... Therefore, it is urgent to find clean, recyclable and low-cost alternatives new energy [6][7][8][9][10]. However, photo-catalytic decomposition of water to produce 1 3 hydrogen is considered to be one of the most promising ways to convert solar energy into a directly usable chemical energy source [11][12][13][14][15][16]. Then, developing efficient photocatalysts is another challenge [17,18]. ...
CdS semiconductor is an excellent photo-catalyst for water-splitting to produce hydrogen. In this study, a binary photo-catalyst Ni3Se4@CdS enhancing hydrogen evolution activity under visible light irradiation was successfully synthesized and their photo-catalytic performance was investigated in detail by a series of characterization technologies. Ni3Se4@CdS sample reveals the higher hydrogen production activity compared with single Ni3Se4 or CdS samples under visible light-driven due to the existence of Ni3Se4 nanoparticels efficiently inhibits the recombination of electron–hole pairs for CdS nanorods as well as improves optical absorption density. Meanwhile, Ni3Se4@CdS catalyst shows the smaller over-potential than CdS nanorods, which also is an important factor to improve photo-catalytic hydrogen generation performance. The loading of Ni3Se4 particles improves the optical absorption intensity of CdS nanorods and enhances the photo-current response. At the same tine, Ni3Se4@CdS composite exhibits the smaller impedance compared with single CdS. Additionally, the surface elements component and specific surface area of the resulting samples also are studied. Finally, based on a great deal of research results, the possible mechanism of photo-catalytic water-splitting is speculated.
Graphic Abstract
... Different evaluations of photocatalytic ability under visible light demonstrated the superior photocatalytic ability of C-TiO 2 materials compared to unmodified materials. Momeni et al. (2016aMomeni et al. ( , 2016b reported fabrication of nitrogen, carbon, and iron multiple-codoped titanium dioxide nanotubes by depositing method on TiO 2 nanotube surface as a new high-performance photocatalyst. At the same time, these authors also synthesized the photocatalytic nanocomposite films of Ag 2 S/TiO 2 by electrochemical anodizing and successive ionic layer adsorption and reaction approach (Momeni et al. 2016a(Momeni et al. , 2016b. ...
... Momeni et al. (2016aMomeni et al. ( , 2016b reported fabrication of nitrogen, carbon, and iron multiple-codoped titanium dioxide nanotubes by depositing method on TiO 2 nanotube surface as a new high-performance photocatalyst. At the same time, these authors also synthesized the photocatalytic nanocomposite films of Ag 2 S/TiO 2 by electrochemical anodizing and successive ionic layer adsorption and reaction approach (Momeni et al. 2016a(Momeni et al. , 2016b. Iron-cobalt WTiO 2 nanotuble (WTNTs) films prepared by the chemical bath deposition method (Momeni et al. 2019). ...
This article introduces research on the synthesis and characteristics of C–TiO2 doped cellulose acetate (CA) nanocomposite film. TiO2 nanoparticles were synthesized from Ilmenite mineral in Binh Dinh, Vietnam, and modified by Stevia Rebaudiana plant in order to serve as a cheap, stable, and eco-friendly photocatalyst that could perform under visible light. Nanocomposite film was obtained by dispersing C–TiO2 on cellulose acetate polymer using a supersonic generator. The prepared material was characterized by X-ray diffractions (XRD), N2 adsorption, Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray analysis (EDX), UV–Vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) emission spectra, scanning electron spectroscopy (SEM), and thermogravimetric/differential thermal analysis (TG-DTA). The film’s photocatalytic efficiency was evaluated via the decomposition of Reactive Red-195 (RR-195) under visible irradiation at room temperature. The results showed that the maximum conversion of RR-195 reached 99.15% at pH = 3 and the activity of the catalyst had a slight decrease after up to four times of recycling, for which the conversion of the fourth reaction was 90.02% for RR-195. This result suggests an efficient treatment method to eliminate organic pollutants from wastewater and stimulate these industrial activities in Vietnam.
... It sensitizes TiO 2 or ZnOphotocatalysis. Ag 2 S-deposited (1) TiO 2 [7,[12][13][14][15][16][17][18][19][20] or (2) ZnO [21][22][23][24] absorbs near infrared, visible and ultraviolet light, the whole solar spectrum, and mineralizes organic pollutants. Ag 2 S acts as a photosensitiser, enables visible light absorption and enhances charge carrier separation between Ag 2 S and TiO 2 [7,[13][14][15][16][17][18]20] or ZnO [23,24]. ...
... Ag 2 S-deposited (1) TiO 2 [7,[12][13][14][15][16][17][18][19][20] or (2) ZnO [21][22][23][24] absorbs near infrared, visible and ultraviolet light, the whole solar spectrum, and mineralizes organic pollutants. Ag 2 S acts as a photosensitiser, enables visible light absorption and enhances charge carrier separation between Ag 2 S and TiO 2 [7,[13][14][15][16][17][18]20] or ZnO [23,24]. Further, Ag 2 S itself is a visible light-near infrared-photocatalyst [10]. ...
Semiconductor-photocatalytic mineralization of organics is an emerging technology. However, recovery of the photocatalytic particles post pollutant-mineralization is a stumbling block for adoption of this technique. Implantation of magnetic core in the particulate photocatalyst ensures magnetic recovery. The magnetic core, deeply buried in the photocatalytic semiconductor lattice, is secluded from the photocatalyst/effluent interface and has insignificant influence on the photocatalytic processes. As the magnetic core is concealed its photocorrosion is overcome. With this, we report synthesis of Fe3O4-implanted Ag2S-capped ZnO microstructure by a two-step hydrothermal process. Scanning electron micrograph shows the synthesized particles as micro-clubbell-shaped. The energy dispersive X-ray spectrum confirms the presence of the constituent elements and the elemental mapping images display the even distribution of the constituent elements in the micro-clubbells. The X-ray diffractogram and the Raman spectrum show ZnO in zincite structure and Ag2S in acanthite phase. The synthesized microstructure and precursor Fe3O4 nanocrystals are superparamagnetic and their magnetic properties are comparable. The charge-transfer resistance of the microstructure is more than 20-fold that of Fe3O4 nanocrystals (New J Chem 40:1845–1852, 2016). The micro-clubbells absorb in the entire visible region and displays strong absorption in the UV-A region. The microcomposite exhibits green and strong blue-green emissions and the lifetime of photogenerated charge carriers is 10 ps. The synthesized microsized clubbell is mesoporous and its specific surface area is comparable to those of nanostructured composites. The synthesized microcomposite (1) displays superior photocatalytic activity under natural sunlight and (2) is reusable and magnetically recoverable. In addition, the title microstructure exhibits bactericidal activity, even without direct illumination.
Graphic abstract
... To improve the utilization efficiency of sunlight radiation and also to enhance the photocatalytic activity, fresh visible-light-driven photocatalysts with high photocatalytic activity and stability has to be designed [7,8,9,10,11]. Through a variety of reports exist in the literature on visible light photocatalysis [12,13,14,15,16,17,18,19,20,21,22,23], certain materials are more responsive to both UV and visible light. Among them, BiFeO 3 (BFO) is a well-familiar and an important semiconductor photocatalyst because of its huge response to solar radiation, band gap and high stability [24,25,26,27]. ...
Perovskite types of nanocomposites of BiFeO3-GdFeO3 (BFO-GFO) has been synthesized using sol-gel route for the first time. The nanocomposite powders were characterized by powder X-Ray diffraction (PXRD) to confirm the existence of mixed crystallographic phases. EDX analysis on nanocomposites estimates the composition of individual element present in BFO-GFO matrix. The induced strain upon loading GdFeO3(GFO) in BiFeO3 (BFO) matrix has been computed with the aid of Williamson -Hall (W-H) plot. Surface morphologies of nanocomposite powders has been studied using Field Emission Scanning Electron Microscope (FESEM) images. The observed changes in the band gap energies of nanocomposite powders due to the inclusion of GFO has been ascertained from the tauc plots. PL emission of BFO upon loading GFO found to have detected in the IR region due to defect level transition. Finally, the methylene blue dye (MB) degradation characteristics of BFO, GFO and the nanocomposite powders of BFO-GFO have also been studied. The overall results obtained has been discussed in detail.
