Synthesis Of TiO2 Nanoparticles Research Articles

Natural Saccharum officinarum (sugarcane) juice assisted TiO2 nanoparticle synthesis for high performance dye-sensitized solar cell

Green chemistry technologies are perceived to be more straightforward, sustainable and cost-effective and therefore explored extensively in recent years. A range of natural reducing and capping agents, viz. proteins, enzymes, and phytochemicals have been used to synthesize TiO2 nanoparticles. The capping agents are vital in stabilizing nanoparticles, avoiding their over-growth and aggregation during synthesis. In this work, green synthesis of TiO2 has been carried out through the sol-gel method using Saccharum officinarum (sugarcane) juice as a capping agent. The optical properties, morphology, size, and porosity of the synthesized TiO2 were characterized by UV, FT-IR, XRD, TEM, and BET respectively. The XRD pattern and TEM confirmed the anatase phase and particle size, while BET revealed surface area and pore sizes. Under irradiance of 100 mWcm−2 light intensity, the photoelectric conversion efficiency using capped TiO2 sensitized with N719 dye was observed to 3.65 %, much enhanced compared to the efficiency 0.69 % observed with the un-capped TiO2. The present study successfully demonstrated that sugarcane phytochemicals have the potential to improve dye-sensitized solar cell (DSSC) efficiency via inducing capping during nucleation in TiO2 synthesis.

Metal Oxide-Based Semiconductor as Photoanode for Photovoltaic Cells

The contributing factors to the overall improvement in photovoltaic efficiency are visible light absorption, enhanced dye absorption, rapid electron transport and minimal carrier recombination. To improve the dye-sensitized solar cells (DSSCs) capacity to harvest light focus is mostly placed on the synthesis of photoanode material. Photo anodes made of several metal oxide semiconductors, such as TiO2, ZnO, SnO2, Nb2O5, etc., have been used in DSSCs. The most suitable material for DSSC use is anatase TiO2 with a band gap of 3.2 eV that is chemically stable, non-toxic, and easily accessible. The synthesis of TiO2 nanoparticles and their morphological variation are described in detail in the paper. The nanoparticles exhibit a tetragonal crystalline structure with lattice parameters a= 3.74 Å and b= 9.39 Å. The effect of sintering temperature on phase transition and on electrical properties affecting particle size and surface area is investigated and optimized. Characterization techniques including X-ray Diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are employed to analyze the TiO2 nanoparticles. These techniques provide insights into the morphology and size of the coated TiO2 nanoparticles. The paper reports the effect of sintering temperature on the efficiency of the fabricated DSSCs. Additionally; it reviews recent advancements in TiO2-based nanomaterials, particularly through doping, to further enhance the efficiency of DSSCs. Overall, the study highlights the importance of optimizing the synthesis and properties of TiO2 nanoparticles for improved performance of DSSCs, and it discusses potential strategies for enhancing the efficiency of DSSCs through modifications in TiO2-based nanomaterials.

Large eddy simulation-bivariate sectional model for non-spherical TiO2 nanoparticle synthesis in flame

Numerical simulation of nanoparticle synthesis in flame necessitates a high level of fidelity for turbulent flame, as well as delivers more detail insight into the evolution of structure and size distribution of particles undergoing various dynamic events. In the present work, a new simulation approach coupling large-eddy simulation (LES) and bivariate sectional model is proposed to explore the synthesis of nanoparticles in turbulent flame. More specifically, the nonlinear LES-partially stirred reactor model (NLES-PaSR) is utilized to simulate the turbulent flame, wherein the gradient-type structural subgrid-scale (SGS) model for turbulent flow and partially stirred reactor (PaSR) model for turbulent combustion are considered. In addition, the volume-based bivariate sectional model is thoroughly coupled with the LES model for the first time to describe the spatiotemporally resolved formation and growth of nanoparticles using particle number concentration and surface area concentration as two sets of variables. Compared directly with the LES-monodisperse (LES-Mono) and LES-univariate sectional (LES-UniSe) models, the LES-bivariate sectional (LES-BiSe) model has significant advantages in its ability to analyze and predict the size, morphology, as well as polydispersed particle size distribution (PSD) evolution of nanoparticles at a moderate computational cost simultaneously. In the LES framework, the proposed model successfully simulates the spatiotemporally resolved formation and growth of non-spherical TiO2 nanoparticle in turbulent diffusion burner. The predicted results derived from the LES-BiSe model are in good agreement with the experimental measurements. Also, the aggregate and primary particle size distribution shows highly temporal fluctuation, which mainly results from the continuous variations of particle path induced by the unsteady turbulent combustion. Furthermore, the present work demonstrates the profound dependence of particle morphological on both spatiotemporal evolution and their intrinsic size distribution. In particular, the large aggregates in the higher sections are commonly found as irregular structure with fractal-like dimensions.

Screen-printed counter-electrodes based on biochar derived from wood-corn silage and titanium isopropoxide binder as a more efficient and renewable alternative to Pt-CE for dye-sensitized solar cells

Current research of counter-electrodes (CEs) for dye-sensitized solar cells (DSSCs) focuses mainly on searching for low-cost and mass-production suitable materials as an alternative to standardly used platinum. One of the most studied groups is carbon allotropes, while carbon-enriched materials such as biochar prepared from renewable sources (biomass) show tremendous potential. Structural properties of biochar, electrical conductivity and large specific area predict the possibility of its use as a catalytic material of CE. To ensure printability and efficient contact between the printed catalytic layer and substrate of CE, non-conductive polymer binders, reducing electrical and electrochemical properties of CEs, are standardly used. This work introduces the preparation of screen-printed CEs based on titanium isopropoxide (TTIP) binder and biochar microparticles obtained by pyrolysis of wood and corn silage, which were investigated as an alternative to platinum CE. TTIP was examined as a substitute for the polymer binder ethylcellulose (EC) and as the precursor for TiO2 nanoparticle synthesis in biochar/TTIP hybrid CEs. Formation of polymer matrix from TTIP ensured the required rheological properties of biochar/TTIP inks and improved interparticle contact and mechanical stability of screen-printed catalytic layers of CEs. Raman spectroscopy indicated the presence of TiO2 anatase nanoparticles with a size of 5 nm after CEs sintering at 500 °C under an argon atmosphere. The sintering process raised catalytic activity and decreased sheet resistance of CEs in the presence of I3−/I− electrolyte, resulting in enhanced photovoltaic parameters of DSSCs. Screen-printed composite CEs consisting of 30 wt% biochar and 20 wt% TTIP reached the best catalytic activity and higher conversion efficiency of DSSCs (6.43 %) than DSSCs with Pt CEs (6.19 %). Based on the results, combining biochar and TTIP offers new possibilities for developing more ecological and low-cost mass-producible materials for CEs.

Toward sustainable nanomaterials: An innovative ecological approach for biogenic synthesis of TiO2 nanoparticles with potential photocatalytic activity

Biogenic synthesis of nanomaterials represents a promising alternative to traditional chemical synthesis due to its environmentally friendly nature, cost-effectiveness, low toxicity, and high biocompatibility. The primary objective of this study was to develop a novel biogenic synthesis method for titanium dioxide (TiO2) nanoparticles using an aqueous extract of Annona muricata L. as a stabilizing and organic reducing agent. Furthermore, our aim included a comprehensive exploration of the structural, morphological, and optical properties of these nanostructures. The methodology employed in this project was grounded in the biogenic synthesis of TiO2, utilizing the aforementioned extract as a key component. We conducted a comprehensive characterization approach to unravel the formation mechanism and validate the morphology and crystalline structure of the nanomaterial. We successfully synthesized nanoparticles with spherical morphology and an average diameter of 13.41 nm, characterized by their remarkable uniformity and high-quality crystalline structure. Additionally, we assessed the applicability of these nanoparticles in photocatalysis processes aimed at the degradation of organic dyes. Our findings indicated efficient initial activity in the kinetics of methylene blue dye degradation, with a reduction of 59.25 % within the first 30 min of exposure.

Effect of calcination temperature on the synthesis of TiO2 nanoparticles from Sutherlandia frutescence for the degradation of Congo red dye and antibiotics ciproflaxin and sulfamethoxazole

Considering that pollutants such as dyes and pharmaceuticals are mutagenic and carcinogenic, they provide a major risk to aquatic life and humans, thereby making their removal to be crucial. The current study is focused on synthesizing TiO2 nanoparticles through the utilization of an aqueous extract from Sutherlandia frutescens. FTIR, XRD, SEM, UV–Vis and EDS techniques were employed for the analysis of the attributes of TiO2 nanoparticles. In accordance with FT-IR analysis, The S frutescens plant's unique functional groups were found to be deposited on the TiO2 nanoparticles which were synthesized. At wavelengths of 352 nm and 370 nm, substantial absorption peaks were seen in UV–Vis confirming the TiO2 formation and the bandgaps were calculated and found to be 3,19 eV, 3.26 eV and 3.29 eV for 400 °C, 450 °C and 500 °C respectively. XRD further confirmed, with the anatase peak of the TiO2 synthesis with a 10.17 average crystallite size. SEM showed the materials were spherical in shape, irregular and unevenly distributed on the surface. The synthesized nanoparticles were subjected to assessment for their photocatalytic performance while exposed to the dye Congo red (CR) and the antibiotics sulfamethoxazole (SMX) and ciprofloxacin (CIP). The highest degradation was reported for the TiO2 NPs @ 400 °C at the optimum dosage of 30 mg to be 87 % against 5 ppm CR dye after 120 mins. Upon reusing this material, its efficiency was reduced to 64 % after the first cycle followed by 61 % then 36 % for the second and third cycle respectively. Moreover, Electrons were the entities accountable for the deterioration of the dyes. Testing against the 10 ppm antibiotics, SMX and CIP had degradations of 82 and 94.6 %, respectively, after an exposure of UV (300 W) light for a period of 120 min. This investigation shows that these environmentally friendly materials can be utilized to degrade a variety of contaminants.

Green synthesis of TiO2 nanoparticles using Terminalia chebula and its potent antibiofilm activity against dental caries-associated bacterium Streptococcus mutans

The production of eco-friendly nanoparticles with biocompatible properties is gaining prominence in global medical research. In this study, we explore the antibiofilm potential of Titanium dioxide nanoparticles (TiO2NPs) synthesized from Terminalia chebula against the oral pathogen Streptococcus mutans. Characterization of TiO2NPs revealed a UV–Vis peak at 322 nm. FT-IR spectrum identified Ti–O–Ti vibrations, hydroxyl, and carboxylic groups. SEM analysis revealed tetragonal TiO2NPs, with EDX confirming titanium. XRD confirmed TiO2 anatase crystallographic planes at 25.8° with an average grain size of the particle of 56 nm. Biofilm inhibitory activity indicated significant inhibition of biofilm with BIC50 of 65.71 μg/ml. Microscopic visualization substantiated the efficiency of TiO2NPs in impeding biofilm formation. Increased TiO2NPs concentrations showed a marked reduction in exopolysaccharide and increased protein leakage from S. mutans after prolonged exposure. These findings suggest TiO2NPs as potential agents for treating dental caries, though further validation is needed for therapeutic use in oral care.

Using biologically synthesized TiO2 nanoparticles as potential remedy against multiple drug resistant Staphylococcus aureus of bovine mastitis

Presently, there is considerable emphasis on biological synthesis of nanoparticles containing bioactive reducing compounds with an aim to mitigate the harmful effects of pollutants. The approach under study is simple and ideal for the production of durable antimicrobial nanomaterials by novel single-step green synthesis of TiO2 metal oxide nanostructures using ginger and garlic crude aqueous extracts with bactericidal and catalytic activity. A variety of experimental techniques were used to characterize the synthesized nanomaterials. As demonstrated using x-ray diffraction and ultra-violet visible spectroscopy, the produced nanoparticles exhibited high absorption at 318 nm with size varying between 23.38 nm for ginger and 58.64 nm for garlic in biologically-reduced TiO2. At increasing concentrations (500, 1000 µg/50 µl), nanoparticles reduced with garlic exhibited enhanced bactericidal efficacy against multiple drug-resistant S. aureus and effectively decomposed toxic methylene blue (MB) dye. In conclusion, biologically-reduced TiO2 nanoparticles may prove an effective tool in the fight against microbial illnesses and drug resistance.

Synthesis, Characterization and Surface Properties of Nano-TiO2 Using a Novel Leaf Extracts

The main focus of research is on the nature of applications in the fields of science and technology, particularly nanotechnology. In this paper, a simple, non-toxic, inexpensive, and environmentally friendly green method was used to synthesize TiO2 nanoparticles using the extraction of portulacaria afra plant leaves and TiCl4 as a precursor. The synthesized titanium dioxide nanoparticles were characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction patterns, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The SEM image of TiO2 nanoparticles showed a few spherical, non-agglomerated particles. The average diameter of the nanoparticles, according to the surface topography of TiO2-NPs, is 70.24 nm. It was found that the average crystalline size was 18.9 nm by utilizing the Debye-Scherrer equation to calculate the size of the crystals. The vibrational mode of Ti-O-Ti exhibits a distinctive peak in the broad band centered at 578.64, 547.78, and 514.99 cm-1, which denotes the development of metal-oxygen bonding, confirming the presence of TiO2-NPs. The specific surface of the synthesized particles was calculated using the Brunauer-Emmett-Teller BET equation.

Green synthesis of TiO2 nanoparticles using Tinospora cordifolia plant extract & its potential application for photocatalysis and antibacterial activity

Green synthesis of TiO2 nanoparticles using Tinospora cordifolia plant extract & its potential application for photocatalysis and antibacterial activity

Partial Hydrolysis of Diphosphonate Ester During the Formation of Hybrid TiO2 Nanoparticles: Role of Acid Concentration.

The hydrolysis of the phosphonate ester linker during the synthesis of hybrid (organic-inorganic) TiO2 nanoparticles is important when forming porous hybrid organic-inorganic metal phosphonates. In the present work, a method was utilized to control the in-situ partial hydrolysis of diphosphonate ester in the presence of a titania precursor as a function of acid content, and its impact on the hybrid nanoparticles was assessed. Organodiphosphonate esters, and more specific, their hydrolysis degree during the formation of hybrid organic-inorganic metal oxide nanoparticles, are relatively under explored as linkers. Here, a detailed analysis on the hydrolysis of tetraethyl propylene diphosphonate ester (TEPD) as diphosphonate linker to produce hybrid TiO2 nanoparticles is discussed as a function of acid content. Quantitative solution NMR spectroscopy revealed that during the synthesis of TiO2 nanoparticles, an increase in acid concentration introduces a higher degree of partial hydrolysis of the TEPD linker into diverse acid/ester derivatives of TEPD. Increasing the HCl/Ti ratio from 1 to 3, resulted in an increase in degree of partial hydrolysis of the TEPD linker in solution from 4 % to 18.8 % under the applied conditions. As a result of the difference in partial hydrolysis, the linker-TiO2 bonding was altered. Upon subsequent drying of the colloidal TiO2 solution, different textures, at nanoscale and macroscopic scale, were obtained dependent on the HCl/Ti ratio and thus the degree of hydrolysis of TEPD. Understanding such linker-TiO2 nanoparticle surface dynamics is crucial for making hybrid organic-inorganic materials (i. e. (porous) metal phosphonates) employed in applications such as electronic/photonic devices, separation technology and heterogeneous catalysis.

Kinetics and Mechanism of Lead Removal from Effluents by Synthesized TiO2 Nanoparticles Via Sol-Gel Method: Adsorption Studies

Water is essential for living organisms, with our bodies containing a significant 60% water content. Water pollution resulting from harmful industrial practices and human activities poses a significant danger to humanity. The release of organic and inorganic substances, pathogens, herbicides, pesticides, drugs, heavy metals, and visible pollutants into water bodies leads to a decline in water quality, causing a reduction in oxygen levels. The toxicity and bioaccumulative properties of heavy metals make them prominent environmental pollutants. Researchers are particularly interested in the adsorption method due to its exceptional ability to eliminate toxic metals, wherein adsorbates bind to the solid surface of adsorbents through physicochemical interactions. In this study, TiO2 nanoparticles were synthesized via solgel method. These nanoparticles were used to remove lead from contaminated water. Various techniques, including XRD and EDX were employed to analyze the nanoparticle synthesis. The Atomic Absorption Spectrophotometer was used to measure the removal of Lead before and after adsorption. Key variables like pH, dosage, and contact time were carefully controlled in the experiments. To ensure the findings, statistical analysis were applied to examine all collected data. The ultimate aim was to enhance the efficiency of heavy metal removal and offer valuable insights into the use of chemically synthesized TiO2 nanoparticles for water purification purposes. This research has the potential to contribute to safer water resources and improved environmental management.

Green Synthesis of TiO2 Nanoparticles using Averrhoa Bilimbi Fruit Extract and their Applications in Photocatalytic Dye Degradation and Anti-bacterial Activities

Due to their numerous distinctive characteristics, nanostructured materials are currently a crucial topic of research. One of the most promising materials today are TiO2 nanostructures, which are one among the transition metal oxides. Due to the absence of any potentially dangerous ingredients and commercially viable procedure, green approaches of nanoparticle synthesis have significant benefit over traditional approaches. The present work reported, the photocatalytic as well as anti-bacterial activity of green synthesized titanium dioxide (TiO2-NPs). An aqueous fruit extract of Averrhoa bilimbi as a capping as well as reducing agent, is utilized for the synthesis of TiO2-NPs. The prepared TiO2-NPs have been characterized by spectral methods using powder XRD (X-ray diffraction) and FTIR (Fourier transforms infrared spectroscopy). Morphological characterization by SEM analysis showed that the synthesized was spherical structure with an average particle size of 60 nm. The photocatalytic dye degradation and anti-bacterial activity have been performed and the result revealed the impressive capability of TiO2-NPs. Hence, the current research work offers a futuristic outlook on a green photocatalysts for profound applications.

Green Synthesis of TiO2 Nanoparticles Using Root Extract of Asparagus racemosus (Shatavari) and Evaluation of its Antibacterial, Antioxidant and Antidiabetic activities

Since ancient times, Asparagus racemosus, a traditional herb with various health advantages, has been used to cure a wide range of illnesses. Researchers sparked a lot of interest in the biological methods for producing nanoparticles (NPs). This study’s objective was to synthesize titanium dioxide nanoparticles (TiO2 NPs) utilizing the top-down nanofabrication method. Asparagus racemosus root extract was used to produce titanium nanoparticles utilizing green chemistry. The nanoparticles were characterized using UV-Visible spectroscopy, SEM (Scanning Electron Microscope), and EDX. According to the SEM images the particles are spherical in shape with an average size of 89.59 nm. The antibacterial activity was done with 3 bacterial strains i.e., E. coli, Pseudomonas aeruginosa and Bacillus subtills. Antioxidant activity was evaluated by DPPH and phosphomolybdate assays, the calculated IC50 was 85.18±0.55 µg/ml and 66.4±1.3 µg/ml respectively. The calculated IC50 value for alpha amylase assay was 46.59±2.81 µg/ml. As per the outcomes it is concluded that the plant mediated titanium nanoparticle is very potent which can be used in pharmaceutical and biomedical areas.

Green synthesis of titanium dioxide nanoparticles using Thymus vulgaris leaf extract for biological applications

In the last few decades, the biosynthesis of nanoparticles using biological agents such as microorganisms or plant extracts has gained a lot of attention due to the growing need for generating safe and non-toxic substances, cost-effective techniques, ecologically friendly solvents, and renewable materials. The aqueous leaf extract of Thymus vulgaris was used in the current investigation to achieve the biosynthesis of TiO2 nanoparticles (TiO2 NPs). In this study, leaf extract was used as a size-reducer in synthesis of TiO2. Thyme leaf extract contains flavonoids, phenols, and saponins, which function as both reducing and stabilising agents and are crucial for the synthesis of TiO2 nanoparticles. Methods such as Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), x-ray diffraction (XRD), photoluminescence (PL), and scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) were used to characterise TiO2 NPs. The XRD investigations showed that titanium dioxide nanoparticles are crystalline and average crystal size is 28 nm. Gram-positive bacteria like S. aureus and B. subtilis as well as Gram-negative bacteria like Pseudomonas aeruginosa were used as standardised test microbial inoculums to evaluate the antibacterial properties of biosynthesised nanoparticles (TiO2 NPs). Against each of the studied bacteria, the TiO2 nanoparticles demonstrated significant antimicrobial activity. TiO2 nanoparticles had the maximum activity against Staphylococcus aureus, with an inhibitory zone diameter of 14 mm at 100 g ml−1. By using DPPH, hydroxyl radical techniques, the comprehensive antioxidant activity of produced NPs was examined.

Enhanced heterogeneous photocatalytic degradation of florasulam in aqueous media using green synthesized TiO2 nanoparticle under UV light irradiation

Enhanced heterogeneous photocatalytic degradation of florasulam in aqueous media using green synthesized TiO2 nanoparticle under UV light irradiation

Influence of chemically synthesized TiO2 nanoparticles for photocatalytic degradation of herbicide atrazine

The selective triazine herbicide atrazine is effective against several grassy and broad-leaf weeds. Because of its poor rate of biodegradability, atrazine herbicide is minimally present in aquatic environments. Despite atrazine's low water solubility, pollution of water resources with extremely hazardous herbicides is a major concern. Long-term negative effects of atrazine include hepatotoxicity, renal toxicity, endocrine disruption, a potential human carcinogen, and impaired vitamin function. The benefits of titanium dioxide include chemical stability, non-toxicity, cost, water insolubility, optical properties, and, most crucially, the ability to be recycled. To improve photocatalytic activity, broaden the UV spectral range to visible light, and inhibit electron-hole recombination, titanium dioxide catalysts are doped with metal and non-metal ions. Titanium oxide nanoparticles have a large specific surface area that ranges from 50 to more than 300 m2 g−1, which increases their ability of adsorption and photocatalysis.In this study, different analysis techniques were employed to characterize TiO2 nanoparticles that includes, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) (before and after experimental investigation). The produced TiO2 nanoparticles were found to be between 200 and 250 nm in size, and the diffraction peaks of TiO2 nanoparticles from XRD analysis are revealed by the peaks at 38.5, 41, 46.5, 63, 74, and 77, respectively and The size of the particles is determined by SEM examination. The optimum process conditions i.e. time − 60 min, rpm of 600, dosage of 1 g/L of catalyst, pH 6, initial concentration of 200 ppm, and temperature of 70 °C. Based on the data obtained in this study, the percentage degradation of Atrazine was determined and was found to be 76.15%.

Visible and Solar Light Degradation of Ciprofloxacin and Norfloxacin using Titania Nanocomposite

A simple sol-gel approach was used to synthesize TiO2 nanoparticles and its composite TiO2-PEG (TPG) using polyethylene glycol (PEG). The synthesized samples were characterized by XRD, SEM -EDX, TEM, UV-DRS, photoluminescence, Raman, XPS and BET-surface area techniques. The development of non-toxic, cost-effective, biocompatible and efficient polymeric nanocomposite increases the mechanical, thermophysical and physico-chemical properties of prepared nanomaterials. PEG affected the reaction with the crystallization process of the prepared titania nanoparticles to a great extent. The antibiotics ciprofloxacin and norfloxacin of fluoroquinolone class are widely used to treat certain bacterial infections and at the same time their residues generate serious health issues due to the lack of proper waste water treatment systems thus causing environmental pollution. The present study is thus focused on synthesizing efficient titania PEG nanocomposite to enhance the photocatalytic degradation of antibiotics in both solar and visible light. Efficiency of degradation was achieved maximum upto 74% with TPG and 64% with pure TiO2 nanoparticles for ciprofloxacin in visible light, similarly the degradation of norfloxacin was achieved 65% with TPG and 57% with TiO2 nanoparticles. Sunlight irradiation resulted in the degradation of ciprofloxacin to 80.2% with TPG and 77% with TiO2 nanoparticles whereas it was 78.7% with TPG and 68.6% with TiO2 nanoparticles for the degradation of norfloxacin. These results indicate that the catalyst TPG showed higher activity in presence of solar and visible light than TiO2 nanoparticles. Recyclability was also studied showing the stability of the photocatalyst used even after five successive runs.

Impact of the Precursor on the Physicochemical Properties and Photoactivity of TiO2 Nanoparticles Produced in Supercritical CO2.

The synthesis of TiO2 nanoparticles (NPs) in supercritical media has been reported over the last two decades. However, very few studies have compared the physicochemical characteristics and photoactivity of the TiO2 powders produced from different precursors, and even fewer have investigated the effect of using different ratios of hydrolytic agent/precursor (HA/P) on the properties of the semiconductor. To bridge this knowledge gap, this research focuses on the synthesis and characterization of TiO2 NPs obtained in a supercritical CO2 medium from four different TiO2 precursors, namely diisopropoxytitanium bis (acetylacetonate) (TDB), titanium (IV) isopropoxide (TIP), titanium (IV) butoxide (TBO), and titanium (IV) 2-ethylhexyloxide (TEO). Further, the effect of various HA/P ratios (10, 20, 30, and 40 mol/mol) when using ethanol as a hydrolytic agent has also been analyzed. Results obtained have shown that the physicochemical properties of the catalysts are not significantly affected by these variables, although some differences do exist between the synthesized materials and their catalytic performances. Specifically, photocatalysts obtained from TIP and TEO at the higher HA/P ratios (HA/P = 30 and HA/P = 40) led to higher CO2 photoconversions (6.3-7 µmol·g-1·h-1, Apparent Quantum Efficiency < 0.1%), about three times higher than those attained with commercial TiO2 P-25. These results have been imputed to the fact that these catalysts exhibit appropriate values of crystal size, surface area, light absorption, and charge transfer properties.

Synthesis of TiO2 nanoparticles and demonstration of their antagonistic properties against selected dental caries promoting bacteria.

To evaluate antagonistic role of titanium oxide nanoparticles against selected dental caries promoting bacteria. This in vitro-experimental study was conducted at Pakistan Institute of Engineering and Applied Sciences (PIEAS), National Institute of Health (NIH) and School of Dentistry (SOD), Islamabad for the period of one year from February 2022 to January 2023. Modified hydrothermal heating method was used to prepare titanium oxide nanoparticles (TiO2Nps). Size, shape, phase, band gap energy, surface and elemental composition of Nps were deciphered by application of various modern techniques including x-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), UV-Vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), energy dispersive x-ray spectroscopy (EDX). Antimicrobial action of nanoparticles was evaluated against representatives of gram-positive (mono-derm) and Gram negative bacteria (di-derm) responsible for promoting dental caries. The zones of inhibition were calculated by disc diffusion method for each bacterial strain. Characterization revealed that TiO2Nps were having an average size of 54nm, showing anatase-rutile phase having spherical, with very few- irregularly shaped particles. TiO2Nps contained only pure titanium and oxygen in the EDX image but organic compounds in FTIR scan. Results of antimicrobial action indicated their potent bactericidal action against Pseudomonas aeruginosa (20mm), Escherichia coli (19mm) and Lactobacillus acidophilus (19nm) while comparatively less activity against Staphylococcus aureus (16mm).. TiO2Nps fabricated by modified protocol displayed an effective antimicrobial activity and can be used as an alternative to the contemporary chemotherapeutics against selected bacterial pathogens to prevent dental caries.