Crystalline TiO2 Nanoparticles Research Articles

Thermal stability enhancement in perovskite solar cells using W-doped ZnO/single crystalline anatase TiO2 nanoparticle bilayer

Abstract The interface between the electron transport layer (ETL) and the perovskite layer is essential for fabricating efficient and stable perovskite solar cells (PSCs). In this study, we introduced a bilayer ETL of W-doped ZnO and single crystalline anatase TiO2 nanoparticles (average diameter = 6-10 nm) to mitigate the degradation between W-doped ZnO ETL and MA-containing perovskite layer. After 12 hours of annealing at 85°C, the perovskite grown on the bilayer exhibited strong perovskite peaks, indicating a significant slowdown in decomposition. Moreover, the bilayer device demonstrated superior thermal stability, retaining over 60% of their initial PCE after 24 hours of annealing, while the W-doped ZnO single-layer device lost all efficiency. PSCs with the W-doped ZnO/Anatase TiO2 bilayer achieved power conversion efficiency (PCE) of 16.63%, compared to 11.88% for the W-doped ZnO single layer. This bilayer application offers a promising pathway for improving both efficiency and stability for perovskite-based optoelectronic devices.

H2O2-assisted room temperature preparation of crystalline TiO2 and Ti3C2Tx-derived C-doped amorphous TiOx homojunction for photocatalytic degradation of tetracycline

The light absorption, active sites, and charge carriers separation of photocatalysts are extremely important factors in the field of photocatalysis. Near-perfect lattice-matched homojunction constructed using disorder engineering and doping strategies is an effective strategy to improve photocatalytic activity. Herein, we developed crystalline TiO2 nanoparticles (NPs) and Ti3C2Tx MXene-derived C-doped amorphous TiOx homojunction (TCT) at room temperature. In this homojunction, TiO2 NPs are evenly distributed on the surface of the C-TiOx nanosheet to form a type-II structure, which promotes the separation of photogenerated carriers. The light absorption range of TCT extends to 550 nm due to the presence of intermediate energy levels in C-TiOx, which increases its photon absorption capacity. Moreover, TCT possesses a large number of oxygen vacancies, which are beneficial for improving the adsorption and degradation of pollutants. These characteristics of TCT could significantly improve its photodegradation performance for tetracycline. Interestingly, the precursor mass ratio of TCT with the best degradation efficiency is different under different illumination conditions, which is attributed to the different band gaps of C-TiOx and TiO2 NPs resulting in different light absorption ranges. This work provides a new approach to rationally designing crystalline and amorphous homojunction for photocatalytic applications.

Effects of TiO2 Nanoparticles Synthesized via Microwave Assistance on Adsorption and Photocatalytic Degradation of Ciprofloxacin.

In this study, the optimal microwave-assisted sol-gel synthesis parameters for achieving TiO2 nanoparticles with the highest specific surface area and photocatalytic activity were determined. Titanium isopropoxide was used as a precursor to prepare the sol (colloidal solution) of TiO2. Isopropanol was used as a solvent; acetylacetone was used as a complexation moderator; and nitric acid was used as a catalyst. Four samples of titanium dioxide were synthesized from the prepared colloidal solution in a microwave reactor at a temperature of 150 °C for 30 min and at a temperature of 200 °C for 10, 20, and 30 min. The phase composition of the TiO2 samples was determined by X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Nitrogen adsorption/desorption isotherms were used to determine the specific surface area and pore size distributions using the Brunauer-Emmett-Teller (BET) method. The band-gap energy values of the TiO2 samples were determined by diffuse reflectance spectroscopy (DRS). The distribution of Ti and O in the TiO2 samples was determined by SEM-EDS analysis. The effects of adsorption and photocatalytic activity of the prepared TiO2 samples were evaluated by the degradation of ciprofloxacin (CIP) as an emerging organic pollutant (EOP) under UV-A light (365 nm). The results of the photocatalytic activity of the synthesized TiO2 nanoparticles were compared to the benchmark Degussa P25 TiO2. Kinetic parameters of adsorption and photocatalysis were determined and analyzed. It was found that crystalline TiO2 nanoparticles with the highest specific surface area, the lowest energy band gap, and the highest photocatalytic degradation were the samples synthesized at 200 °C for 10 min. The results indicate that CIP degradation by all TiO2 samples prepared at 200 °C show a synergistic effect of adsorption and photocatalytic degradation in the removal process.

Laser-assisted chemical bath deposition of TiO2 nanoparticles for UV photodetection

Extensive research has been conducted on UV photodetectors employing titanium dioxide nanoparticles (TiO2-NPs), which exhibit numerous advantageous qualities, notably encompassing fascinating switching behaviour and strong photosensitivity. An efficient TiO2 NPs synthesis process is essential for the quality and output of photodetectors. A quick synthesis process can lead to less energy and cost consumption, sustainable production processes, increased reaction rate, and improved homogeneity of the reaction resulting high quality films with low impurities. In this study, we exhibited a simple and quick laser-assisted chemical bath deposition (LACBD) method to synthesize high crystalline TiO2 nanoparticles for UV detection. The TiO2-NPs were synthesized by irradiating the tiny area between aluminium (Al) electrodes submerged in TiO2 precursor (in situ chemical bath) with a blue laser of wavelength (460 nm), power (1 W), and deposition duration (25 minutes). UV photodetector built from TiO2-NPs with (Al/TiO2-NPs/Al)/Glass architecture was examined, and our findings proved that TiO2 synthesized by LACBD has potential UV sensing and detecting properties. TiO2-NPs were examined by FESEM, EDX, and XRD. Measurements of current-voltage, I-V and current-time, I-T were employed to analyze the (Al/TiO2-NPs/Al)/Glass UV photodetector performance. Based on the results, it proved that the synthesis method of TiO2-NPs by LACBD is a promising and viable route, resulting in satisfactory reaction yield and low contamination. The responsivity, specific detectivity, and external quantum efficiency could reach as high as 1.36e-1 A/W, 2.87e+7 Jones and 46.1 % respectively at −5 V bias voltage.

Agro-waste mediate to synthesize the solar light active titanium dioxide nanoparticles with enhanced efficacy of pollutant removal

In this research work, Titanium dioxide (TiO2) nanoparticles were prepared from green waste by Wet Chemical method. Titanium tetraisopropoxide (TTIP) precursor is converted to TiO2 nanoparticles by using the Musa-paradisiaca L. (Banana crop) pseudo stem extract as a capping agent. The non-dopant, anatase phase crystalline TiO2 nanoparticles were synthesized and characterized by using analytical techniques like TEM, HR-TEM, SAED, BET, FTIR, SEM, EDX, XRD, XPS, DRS, UV-Visible spectrophotometer and Zeta Potential. The green synthesized TiO2 nanoparticles with band gap energy 2.95 eV were used as a photocatalyst for the degradation of Indigo Carmine (IC) dye under solar radiation with an intensity of 1200*100 lux. Optimization process was carried out for three factors such as catalyst dosage, pH and concentration of the dye solution at constant time. TiO2 nanoparticles photocatalyst showed 99% degradation efficiency in 30 minutes (min) for the IC dye under optimum condition. This experimental work was confirmed by comparing with the theoretical results obtained from Response Surface Methodology (RSM). The RSM of the quadratic model produces a theoretical layout for the optimization process and provides the Analysis of Variance (ANOVA) data which evaluate the importance of each experimental factor. The RSM results are well matched with the R2 value obtained from the experimental method. The biogenic TiO2 nanoparticles had greater efficacy in the degradation of IC dye for five cycles of reaction.

Controllable and facile one-pot synthesis of high surface area amorphous, crystalline, and triphasic TiO2: catalytic and photocatalytic applications

A simple and controllable synthesis led to both amorphous and crystalline porous TiO2with remarkably high surface area and pore volume. Their distinctive characteristics influenced their effectiveness in photocatalytic and catalytic processes.

Mechanism and performance evaluation of spent-coffee grounds-derived nanocomposite materials for highly efficient photocatalytic degradation of organic pollutant

The study demonstrates a facile and environmentally friendly method for synthesizing crystalline TiO2 nanoparticles on the surface of hydrochar generated from readily available biomass waste, i.e., spent coffee grounds (SCGs), using a simple sol–gel process. The hydrochar served as a support for TiO2, reducing the rate at which electrons and holes recombine during photocatalysis, thereby facilitating the effective binding of TiO2, enhancing its adsorption capacity, and the convenient separation of the photocatalyst after usage. The materials were tested in the photocatalytic degradation of an organic pollutant, methylene blue (MB) dye. TiO2-hydrochar obtained at 210 ⁰C has the best performance, giving a degradation efficiency of 98.5 % and a mineralization efficiency of 87.1 % in 90 min at neutral pH. Radical trapping experiments showed O2.-andh+ being the dominant species, followed by HO.. Besides, it showed superior stability with an activity loss of ∼ 9.2 % after five runs. The superior performance of the HCT210 was ascribed to the enhanced interfacial charge transfer kinetics between the TiO2 and hydrochar through Ti-O-C bond formation, better light absorption, and the high surface area of the materials. Performance metrics show that synthesized nanocomposites are promising photocatalysts, providing a biomass-assisted method for robust photocatalytic wastewater treatment.

Crystallinity swayed phase transformation and oxygen vacancy formation in TiO2 aerogel photocatalysts

The lack of crystallinity of the aerogel materials has limited their significance which otherwise have found huge potential in wide variety of applications. In current work, we have developed TiO2 aerogels by solid-state gelation method using commercially available P25 and ST-01 (commercial Ishihara TiO2 Powder). The lack of crystallinity in the aerogel framework was resolved via utilizing crystalline TiO2 nanoparticles and the phase transformation was assessed as a function of phase composition. Via controlled solid-state gelation, surface area retention of 88.7% was achieved whereas the rutile-to-anatase weight fraction (WR) was considerably enhanced to 0.50. Interestingly, the phase transformation occurred only in P25, which suggests the mixed phase (anatase + rutile) composition as prerequisite for successful phase transformation. Favorably, TiO2 aerogels imbibe high degree of oxygen vacancies (Vo) responsible for photocatalytic applications. Interestingly, Vo induction is higher for the TiO2 with anatase phase composition (ST-01) followed by the sample with mixed phase composition (P25). The developed TiO2 aerogel photocatalysts were employed to dye degradation of Rhodamine B (RhB) and Methylene Blue (MB). The samples attained 94.8% and 96.8% degradation efficiency within 15 min for RhB and MB with nearly 2-fold improvement in the photocatalytic efficiency compared to parent P25 TiO2 respectively.

Hydrothermal synthesis of carbon-coated mixed crystalline phase TiO2 nanoparticle carbon microsphere composites as high performance anode materials for Li-ion batteries

Hydrothermal synthesis of carbon-coated mixed crystalline phase TiO2 nanoparticle carbon microsphere composites as high performance anode materials for Li-ion batteries

Green Synthesis of Titanium Dioxide Nanoparticles Using Ocimum sanctum Leaf Extract: In Vitro Characterization and Its Healing Efficacy in Diabetic Wounds.

Diabetes mellitus is one of the most prevalent metabolic disorders characterized by hyperglycemia due to impaired glucose metabolism. Overproduction of free radicals due to chronic hyperglycemia may cause oxidative stress, which delays wound healing in diabetic conditions. For people with diabetes, this impeded wound healing is one of the predominant reasons for mortality and morbidity. The study aimed to develop an Ocimum sanctum leaf extract-mediated green synthesis of titanium dioxide (TiO2) nanoparticles (NPs) and further incorporate them into 2% chitosan (CS) gel for diabetic wound healing. UV-visible spectrum analysis recorded the sharp peak at 235 and 320 nm, and this was the preliminary sign for the biosynthesis of TiO2 NPs. The FTIR analysis was used to perform a qualitative validation of the biosynthesized TiO2 nanoparticles. XRD analysis indicated the crystallinity of TiO2 NPs in anatase form. Microscopic investigation revealed that TiO2 NPs were spherical and polygonal in shape, with sizes ranging from 75 to 123 nm. The EDX analysis of green synthesized NPs showed the presence of TiO2 NPs, demonstrating the peak of titanium ion and oxygen. The hydrodynamic diameter and polydispersity index (PDI) of the TiO2 NPs were found to be 130.3 nm and 0.237, respectively. The developed TiO2 NPs containing CS gel exhibited the desired thixotropic properties with pseudoplastic behavior. In vivo wound healing studies and histopathological investigations of healed wounds demonstrated the excellent wound-healing efficacy of TiO2 NPs containing CS gel in diabetic rats.

Fabrication of omnidirectional broadband dual-functional coating with high optical and self-cleaning properties for photovoltaic application

Escalating the transmitted irradiation, which diminishes due to the undesirable reflection at the interfaces and the surface dirt, requires a simultaneous functioning of antireflection and self-cleaning coating for photovoltaic modules. In this regard, an unprecedented, facile, economical, reproducible, and eco-friendly fabrication of dual-functional coatings (Anti-reflective and Self-cleaning) with high optical and photocatalytic properties is demonstrated. Highly crystalline MgF2 and TiO2 nanoparticles are successfully synthesized by the solvothermal method, and these nanoparticles are utilized to develop a dual-functional coating. HR-TEM and XRD are used to analyze the synthesized nanoparticles, and FE-SEM measures the coating morphology and thickness. The established dual-functional coating exhibits a 5 % enhancement in transmittance compared to uncoated glass in the 380–1100 nm wavelength range. The developed coating also shows high omnidirectional broadband antireflective property with 5–33 % net enhancement in the transmittance in the angle of incidence from 10 to 80°. The coating also exhibited good photocatalytic self-cleaning activity by degrading Methylene blue solution in 3 h with minimal loss in transmission. The bilayer dual-functional coating exhibited a net enhancement of 3.5 % in the power conversion efficiency for coated glass placed over a mini-module compared to uncoated glass positioned over a mini-module. This bilayer dual-functional coating offers enormous potential benefits and is highly conceivable for many applications.

A Facile One-Pot Approach to the Fabrication of Nanocellulose-Titanium Dioxide Nanocomposites with Promising Photocatalytic and Antimicrobial Activity.

The combination of cellulosic materials and metal oxide semiconductors can provide composites with superior functional properties compared to cellulose. By using nanocellulose derived from agricultural waste, we propose a one-pot and environmentally friendly approach to the synthesis of nanocellulose–TiO2 (NC–TiO2) nanocomposites with peculiar photocatalytic activity and antibacterial effects. The as-prepared NC–TiO2 composites were fully characterized by different techniques, such as X-ray diffraction (XRD), μ-Raman, Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The results showed that well crystalline anatase TiO2 nanoparticles of about 5–6 nm were obtained. The photocatalytic activity in particular was evaluated by using methyl orange (MO) solution as a target pollutant at different pH values. It was found that all the tested NC–TiO2 nanocomposites showed stable photocatalytic activity, even after consecutive photocatalytic runs. In addition, NCT nanocomposites with higher TiO2 content showed degradation efficiency of almost 99% towards MO after 180 min of UV illumination. Finally, NC–TiO2 nanocomposites also showed intriguing antimicrobial properties, demonstrating to be effective against Gram-positive (Staphylococcus aureus, Bacillus subtilis) with 20–25 mm of inhibition zone and Gram-negative bacteria (Escherichia coli, Pseudomonas aeuroginosa) with 21–24 mm of inhibition zone, and fungi (Candida albicans) with 9–10 mm of inhibition zone.

Synthesis, Characterization and Photocatalytic Performance of Poly-3-Thenoic Acid/Cu-TiO2 Nanohybrid for Efficient Visible Light Assisted Degradation of Bismarck Brown R

The present work reported on the synthesis and characterization of Poly-3-Thenoic acid/Cu-TiO2 nanohybrid (PCuT) for the photocatalytic degradation of organic azo dye pollutant from wastewater. The as-synthesized nanohybrid by an in-situ modified sol-gel method including chemical oxidative polymerization was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, UV-visible diffuse reflectance spectroscopy (UV-vis.DRS), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and Brunauer-Emmet-Teller (BET) surface area analysis. The characterization results revealed the formation of small aggregates of polymer contained high crystalline anatase TiO2 nanoparticles (XRD) with narrowed bandgap energy (UV-vis.DRS), decreased particle size (TEM) with smooth surface morphology (SEM) and large surface area (BET). All the constituent elements of the polymer and Cu-TiO2 were found in the PCuT nanohybrid material (EDX) and their chemical interaction studied by FT-IR confirmed the stability of the nanohybrid. The photocatalytic activity of the nanohybrid was tested by the degradation of Bismarck Brown R dye under visible light irradiation. To enhance the photocatalytic efficiency, effects of various catalyst/dye reaction parameters such as polymer content, solution pH, catalyst dosage, and initial dye concentration were studied and optimized.
 HIGHLIGHTS
 
 Poly-3-Thenoic acid/Cu-TiO2 nanohybrid material was successfully synthesized by in situ modified sol-gel process
 Poly-3-Thenoic acid has enhanced the visible light absorption capacity of anatase TiO2 in nanohybrids
 Electron-hole recombination in TiO2 was effectively inhibited by Cu doping
 Bismark Brown R, an organic pollutant was successfully degraded in 75 min of visible light irradiation
 
 GRAPHICAL ABSTRACT

Microwave-Assisted Vacuum Synthesis of TiO2 Nanocrystalline Powders in One-Pot, One-Step Procedure.

A new method for fast and simple synthesis of crystalline TiO2 nanoparticles with photocatalytic activity was developed by carrying out a classic sol–gel reaction directly under vacuum. The use of microwaves for fast heating of the reaction medium further reduces synthesis times. When the solvent is completely removed by vacuum, the product is obtained in the form of a powder that can be easily redispersed in water to yield a stable nanoparticle suspension, exhibiting a comparable photocatalytic activity with respect to a commercial product. The present methodology can, therefore, be considered a process intensification procedure for the production of nanotitania.

TiO2@SiO2 nanoparticles for methylene blue removal and photocatalytic degradation under natural sunlight and low-power UV light

We have developed an efficient SiO2-TiO2 nanoparticle system with enhanced photocatalytic degradation under natural sunlight and low-power UV light. The SiO2-TiO2 system was synthesized by adding different mole ratios of SiO2 to TiO2, the ratios of 10:1, 5:1, and 2:1 have been used. SiO2-TiO2 nanoparticles with a 2:1 mole ratio showed enhanced photocatalytic degradation of methylene blue (MB) due to the presence of highly crystalline anatase TiO2 nanoparticles as well as good adsorption capacity due to the highly porous nature of samples. SiO2-TiO2 with a mole ratio of 5:1 showed the highest adsorption capacity of 88.6% after 30 min under dark conditions. Photocatalytic degradation of 90% and 85% was achieved for Si2Ti after 30 min in sunlight and UV light respectively. In addition, almost complete degradation of MB (98%) was obtained after 2 h in sunlight.

Significant efficiency enhancement of CdSe/CdS quantum-dot sensitized solar cells by black TiO2 engineered with ultrashort filamentating pulses

While the efficiency of quantum dot sensitized solar cells (QDSSCs) has been long limited by photogenerated electron extraction of photoanode, we propose here an alternative approach for boosting the light harvesting efficiency of QDSSCs, which is based on the modifications of the TiO2 photoanode absorbance and impedance by irradiating crystalline TiO2 nanoparticles with intense femtosecond laser pulses propagating in the filamentation regime. We demonstrate that a two-fold enhancement of the power conversion efficiency in CdSe/CdS-cosensitized solar cells is unambiguously achieved with the produced “black” TiO2 nanoparticles as photoanode, which allows for the light absorption in the spectral range of 240-2500 nm and enables possible facilitation of electron transport. Our results offer a viable route to boosting QDSSCs efficiency that is normally realized by optimizing the photoanode material morphology and structure as well as quantum dot species in QDSSCs.

Synergistic effects of acetic acid and nitric acid in water-based sol–gel synthesis of crystalline TiO2 nanoparticles at 25 °C

Synergistic effects of acetic acid and nitric acid in water-based sol–gel synthesis of crystalline TiO2 nanoparticles at 25 °C

Eco-Friendly Colloidal Aqueous Sol-Gel Process for TiO2 Synthesis: The Peptization Method to Obtain Crystalline and Photoactive Materials at Low Temperature

This work reviews an eco-friendly process for producing TiO2 via colloidal aqueous sol–gel synthesis, resulting in crystalline materials without a calcination step. Three types of colloidal aqueous TiO2 are reviewed: the as-synthesized type obtained directly after synthesis, without any specific treatment; the calcined, obtained after a subsequent calcination step; and the hydrothermal, obtained after a specific autoclave treatment. This eco-friendly process is based on the hydrolysis of a Ti precursor in excess of water, followed by the peptization of the precipitated TiO2. Compared to classical TiO2 synthesis, this method results in crystalline TiO2 nanoparticles without any thermal treatment and uses only small amounts of organic chemicals. Depending on the synthesis parameters, the three crystalline phases of TiO2 (anatase, brookite, and rutile) can be obtained. The morphology of the nanoparticles can also be tailored by the synthesis parameters. The most important parameter is the peptizing agent. Indeed, depending on its acidic or basic character and also on its amount, it can modulate the crystallinity and morphology of TiO2. Colloidal aqueous TiO2 photocatalysts are mainly being used in various photocatalytic reactions for organic pollutant degradation. The as-synthesized materials seem to have equivalent photocatalytic efficiency to the photocatalysts post-treated with thermal treatments and the commercial Evonik Aeroxide P25, which is produced by a high-temperature process. Indeed, as-prepared, the TiO2 photocatalysts present a high specific surface area and crystalline phases. Emerging applications are also referenced, such as elaborating catalysts for fuel cells, nanocomposite drug delivery systems, or the inkjet printing of microstructures. Only a few works have explored these new properties, giving a lot of potential avenues for studying this eco-friendly TiO2 synthesis method for innovative implementations.

High surface area TiO2 nanoparticles: impact of carboxylporphyrin sensitizers in the photocatalytic activity

TiO2 nanoparticles in anatase-brookite phases were synthesized, modified with (5,10,15,20-tetrakis(carboxyphenyl)porphyrinate)manganese(III) - [MnIII(T4CPP)] and (5,10,15,20-tetrakis(carboxyphenyl))porphyrin – H2T4CPP, and their photocatalytic activities were evaluated by the degradation of methylene blue dye. The prepared materials were characterized by XRD, Raman, gas adsorption, HRTEM-EDS, EELS, fluorescence spectroscopy, and XPS. These techniques provide direct evidence that crystalline TiO2 nanoparticles with high specific surface area were prepared from aqueous TiCl4 precursor and had their surfaces modified by porphyrins. Differences in textural properties between TiO2 samples modified with H2T4CPP and [MnIII(T4CPP)] evidenced the role of the MnIII and carboxyl groups in anchoring these molecules on the TiO2 surface. This molecular configuration was important for understanding the photocatalytic performance associated with the charge transfer between TiO2 and the sensitizers.

Morphology regulation of TiO2 thin film by ALD growth temperature and its applications to encapsulation and light extraction

As a multi-functional material, TiO2 thin film has been widely studied and applied in display, photocatalysis, solar cells and other fields. In this work, TiO2 thin films were prepared using atomic layer deposition, and their morphology was successfully regulated by the growth temperature. It was found that TiO2 film prepared at low temperature was amorphous, uniform and dense, with great barrier property, which can be used for encapsulation. Crystalline TiO2 nanoparticles with anatase phase appeared at higher temperature than 150 °C, whose amount increased with the growth temperature. The crystalline TiO2 particles can be used as templates to prepare randomly textured nano-patterns, which were proved to be able to improve the light extraction efficiency of photoelectric devices. Specifically, the luminance efficiency of the QLED with the nano-patterns formed by the crystalline TiO2 particle prepared at 200 °C and 250 °C were increased by 24.07% and 30.44%, respectively.