Barium Titanate Nanoparticles Synthesized via Green Method for Corrosion Resistance and Biomedical Applications

Abstract

Barium Titanate Nanoparticles Synthesized via Green Method for Corrosion Resistance and Biomedical Applications Abstract: Barium titanate nanoparticles (BaTiO₃ NPs) were synthesized through an exothermic combustion method using barium nitrate, titanium tetra-n-butyl titanate as sources of barium and titanium respectively, with Ipomoea purpurea flower extract serving as a green reducing agent. Qualitative phytochemical screening of the flower extract revealed the presence of several phyto-constituents that might responsible for combustion. The barium titanate phase was achieved as the synthesized material underwent an extra calcination step at 1200 ℃. The formation of the BaTiO₃ phase was confirmed through X-ray diffraction, while its surface morphology was examined via scanning electron microscopy and transmission electron microscopy. Further, characterization was performed using Fourier infrared transform spectroscopy and UV-Vis spectroscopy. The synthesized BaTiO₃ NPs demonstrated significant antioxidant activity, suggesting their potential for biomedical applications. Additionally, their effect on seed germination rates indicates promising agricultural applications. Electrochemical studies revealed the nanoparticles' potential for anti-corrosive, energy storage, and conversion technologies. This comprehensive study not only elucidates the diverse properties of BaTiO₃ NPs but also emphasizes their broad potential across medicine, agriculture, and energy sectors. Keywords: BaTiO₃ NPs; Ipomoea purpurea flower extract; Biomedical applications; Anti-corrosive; Energy storage

Specification

Description:DESCRIPTIONS:
1.0 Introduction
ABX₃ perovskite-based materials have garnered significant research interest for a range of electronic and optoelectronic applications. Their potential relies on the ability to govern the energy band gap utilizing different dopants, positioning perovskites as interesting candidates for a range of applications. Among the diverse perovskite materials, BaTiO₃ has demonstrated notable versatility and potential for numerous uses. BaTiO₃, a quintessential perovskite material, exhibits unique physical and chemical characteristics that are influenced by its morphology and particle size. To ensure optimal performance in practical applications, NPs must be highly purified. BaTiO₃ is a ferroelectric perovskite oxide and is predominantly utilized in multilayer ceramic capacitors due to its high dielectric constant and low loss properties. As one of the most extensively studied perovskite materials, BaTiO₃ is widely used in the fabrication of multilayer ceramic capacitor. Its bandgap measures 3.2 eV at ambient temperature but can grow to around 3.5 eV when the particle size reduces from 15 nm to 7 nm. In 2010, BaTiO₃ was first employed in therapeutic applications, demonstrating its ability to absorb and deliver doxorubicin to SH-SY5Y cells through non-covalent interaction. BaTiO₃ has been widely investigated due to its diverse applications. Its versatility is showcased across various fields, including actuators, microwave technologies, energy storage, gas sensing, spintronics, magnetoelectrics, and multilayer capacitors. Beyond these, BaTiO₃ finds use in non-enzymatic glucose sensing, hydrophobic coatings, and even photoluminescence. The biomedical potential of BaTiO₃ is equally impressive.
Studies have demonstrated its antibacterial properties against P. aeruginosa and S. aureus and its ability to inhibit biofilm formation in these bacteria. Additionally, BaTiO₃ NPs have shown promise in preventing Staphylococcus epidermidis adhesion in maxillofacial silicone applications. In the realm of cancer research, BaTiO₃ has exhibited significant anticancer activity against cell lines such as MCF-7, A-549, HEK-293, and HCT-116. Also, nanomaterials offer better corrosion prevention characteristics since their surface-to-volume ratio has increased. Several researchers have proved the effectiveness of nanomaterials as corrosion inhibitors. This report outlines recent trends and developments in nanomaterials and their application to control corrosion rates. The use of organic and inorganic chemicals as corrosion inhibitors has raised substantial concerns in recent decades due to environmental toxicity. The nanoparticles adhere to the corroded metal surface by physisorption/chemisorption and suppress corrosion effectively. So, using nanoparticles as corrosion inhibitors in coatings will improve active corrosion protection and extend their lifetime. Innovative approaches to NPs synthesis prioritize conditions like cost-effective, environmentally sustainable, and occur at room temperature and neutral pH. With these objectives in mind, various synthesis methods have been explored. The rising demand for 'green' processes in chemistry and chemical technologies is a response to our global environmental challenges. Green nanotechnology offers a promising path to minimize the adverse impacts associated with the production and use of nanomaterials, reducing the inherent risks of nanotechnology. Specifically, green synthesis using plant leaf extract stands out as a sustainable, eco-friendly, and cost-efficient method for producing NPs. Solution combustion synthesis (SCS) is particularly noteworthy for its time- and energy-saving advantages compared to other synthesis methods. It is particularly effective in the synthesis of complex oxides and is easily scaleable. SCS is widely employed for producing inorganic ceramic and composite materials with tailored properties for a wide range of applications, including catalysis, photocatalysis, electrocatalysis, heavy metal removal, sensor technologies, electronics, and medical applications. The versatility and effectiveness of this technique have led to the development of numerous variants, which have significantly optimized the materials produced. Furthermore, its ecologically safe character has prompted more research into the use of sustainable precursors for nanomaterial production in compliance with the principles of a circular economy.
The genus Ipomoea, with more than 500 species, belongs to the Convolvulaceae family and consists of nearly 1,650 predominantly tropical species. From ancient times, some important species of Ipomoea have been extensively used for different medicinal and nutritional purposes. The flowers of Ipomoea purpurea contain cyanidins and pelargonidins, which have antioxidant properties. With the above background, the current work aims at the development of BaTiO3 NPs by SCS using the aqueous extract of leaves of Ipomoea purpurea as fuel. The developed NPs were characterized by distinctive physic-chemical methods such as powder X-ray diffractogram (PXRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), UV-Visible (UV-Vis), and Fourier transform infrared spectroscopy (FTIR). Surface are measurement was carried out by Brunauer-Emmett-Teller (BET) technique. This comprehensive study not only elucidates the diverse properties of BaTiO₃ NPs but also emphasizes their broad potential application in the fields of medicine, agriculture, electrochemical, and energy sectors.



2.0 Materials and Methods
2.1 Chemicals and reagents
Barium nitrate [Ba(NO3)2, 99 %, SD Fine], Titanium tetra-n-butyl titanate (Sigma Aldrich), 2,2-diphenyl-1-picrylhydrazyl. (DPPH, Sigma), Ferric Reducing Antioxidant Power (FRAP kit, Sigma), and Methanol (AR, SD Fine) were purchased in India. The flowers were collected from Vidyaranyapura, Bengaluru, India, washed well with water, and shade-dried for 15 days.

2.2 Preparation of green extract
The powdered flowers of Ipomoea purpurea were subjected to Soxhlet apparatus and heated at 80°C for around 24 hours. Once the process was complete, the mixture in the flask was filtered through Whatman No.1 filter paper, and the filtrate was collected in a glass container. The filtrate, in measured amounts, was utilized as a green biofuel.

2.3 Phytochemical screening of plant extract
Following standard protocols, the aqueous plant extract was subjected to qualitative screening to determine the presence of phyto-constituents.

2.4 Synthesis of BaTiO3 NPs
First, 3.4 mL of tetra-n-butyl titanate was taken, and 10 mL of distilled water was added. The mixture was stirred well. Then, 10 mL of 1:1 nitric acid was added to obtain TiO(NO3)2. 2 g of Barium nitrate and 10 mL of plant extract was added to the above mixture. It was mixed thoroughly and heated in a preheated muffle furnace at 450°C. The amorphous product was then calcined at 1200 °C for 2 hrs.

2.5 Characterisation techniques
A sequence of analytical methods was employed to characterize the synthesized NPs, including PXRD, FTIR spectroscopy, SEM, EDX, and UV-vis spectroscopy. XRD patterns were recorded using a Shimadzu diffractometer (PXRD 7000) with Cu Kα radiation (λ = 1.5406 Å) over a 2θ range of 30˚ to 75˚. The surface morphology of the NPs was analyzed through scanning electron microscopy (SEM, JEOL JSM 6390) and transmission electron microscopy (Philips CM200). UV-Vis optical absorption spectra were measured using a UV-Vis spectrophotometer (Model: Lambda 35, Perkin Elmer), covering wavelengths from 200 to 800 nm in diffuse reflectance mode. Chemical bonding was assessed with an FTIR spectrometer (Bruker Alpha-1, KBr windows, 2 cm-1 resolution) in the 400-1000 cm-1 range. Brunauer-Emmett-Teller surface areawas measured by nitrogen adsorption isotherms on Quantachrome.
2.6 Biological studies and Antioxidant activity
2.6.1 DPPH activity
The antioxidant activity of the sample was evaluated following the method described in the literature. The free radical scavenging percentage of the sample was calculated using the following equation (1)


Where, A0=Absorbance of the control (without extract) A1 =Absorbance in the presence of the extract.

2.6.2 DPPH activity of TLC separated sample
TLC combined with the DPPH radical scavenging assay was used to assess and verify the antioxidant activity of the flour and cookie extracts. The extracts were spotted onto TLC plates using a capillary tube and left to dry (Merck). After drying, the TLC plates were sprayed with a 0.4% methanolic DPPH solution. Control experiments involved TLC plates without DPPH application and those sprayed with DPPH but lacking the extracts.

2.6.3 Reducing power assay (FRAP)
The reducing power capacity was evaluated following the method outlined by Dharmishtha et al. (2009).

2.7 Assessment of seed germination rates
2.7.1 Collecting seeds and soaking them in NPs
Fenugreek (Trigonella foenum- graecum) seeds were obtained from Lalbagh, Bengaluru, India. To ensure seed viability, they were first submerged in water, with only the seeds that sank being selected for further use. The selected seeds were washed with 70% ethanol for five minutes and sterilized in a 2.5% sodium hypochlorite solution for 15 minutes. After sterilization, the seeds were rinsed three times with distilled water. The viable seeds were subsequently immersed in either distilled water (DW) or solutions containing 1.0, 2.5, and 5.0 mM of BaTIO3 NPs for 3 hours, placed in separate Petri dishes at room temperature, and occasionally stirred. Distilled water was used as a control in the experiment.



2.7.2 Determination of seed germination rate and shoot & root length measurement
A total of ten healthy and similarly sized seeds were picked and planted evenly spaced in a seedling tray with sterilized coco peat as the growing medium, which helped to minimize the risk of soil-borne diseases. The rate of seed germination was then determined using this formula (2)
Germination % = (Number of seeds germinated/Total Number of Seeds) × 100……..(2)

2.7.3 Average plant height and root shoot ratio
The experiment was conducted under controlled laboratory conditions with a 12-hour light and 12-hour dark cycle. After harvesting the fenugreek plants, the number of plants, as well as the height of shoots and roots, were measured and averaged. To determine the root-to-shoot ratio, the roots were separated from the shoots at the soil line. Each root and shoot was weighed and recorded individually for each plant. The root-to-shoot ratio was then calculated using the following formula (3)

Root/shoot ratio = Dry weight for roots/dry weight for the top of the plant………(3)

2.7.4 Photosynthetic pigment contents
500 mg of plant material was placed in a mortar and macerated under low light conditions. The macerate was then transferred to a test tube, and 10 mL of a 99% acetone in ethanol solution (2:1 v/v) was added. The mixture was vortexed and then incubated in darkness at -20°C for 30 minutes before centrifugation at 2000 rpm for 10 minutes. Following centrifugation, 5 mL of the acetone/ethanol solution (2:1 v/v) was added and stirred for 1 minute. Absorbance readings were taken at 663 nm and 645 nm, with acetone/ethanol (2:1 v/v) serving as the control. The estimation of photosynthetic pigments was carried out using the formulas provided by Gu D.-D et al. (2016).

Chlorophyll a (mg/g) = (12.7 x A663) − (2.59 x A645)
Chlorophyll b (mg/g) = (22.9 xA645) − (4.7 x A663)
Chlorophyll total (mg/g) = (8.2 x A663) + (20.2 x A645)
Where, 𝐴663, and 𝐴645 represent the absorbance measured at 663 nm and 645 nm, respectively. The spectrophotometer was calibrated to zero using the acetone/ethanol mixture.

2.8 Catalytic degradation of organic dyes
The synthesized NPs were used for the catalytic degradation of organic dyes such as, Malachite green (MG), Coomassie Brilliant Blue (CBB), Brilliant blue (BB), and Phenol red (PR) as shown in Fig13, under dark as per Altaf et al. with slight modification. 100 µg of NPs was added to 1 ml of 10 mM dyes. The solution was mixed using a cyclomixer and placed in the dark for 1 hr at room temperature. A sample of degraded dye was measured using UV-Vis spectroscopy at 617 nm (MG), 584 nm (CBB), 629 nm (BB), and 570 nm (PH). The volume of all the dye solutions was kept constant by using double distilled water. The catalytic gradation efficiency was calculated using the equation (4)


Where, Adye0 is the absorbance of dye and Adye1 is the absorbance of degraded dye by NPs.


2.9 Electrochemical techniques
2.9.1. Materials and sample preparation
The mild steel (MS) with the elemental composition (96.46% Fe, 0.16% P, 0.76% Mn, 0.05% Si, 0.19% S, and 2.38% C) was selected. The MS was cast using a dental cold setting resin exposing a 1 cm2 area and covering the rest. The MS was then polished using emery papers of different grades from 150 to 1600 and with a disc polisher to get the mirror finish. The sample was then made available for corrosion testing for blank and different inhibited concentrations. Chemicals like ethanol (98%), sulphamic acid, and HCl (37%) of analytical grades were purchased from Merck India. The polished MS of area 1cm2 was subjected to electrochemical studies (PDP and EIS) containing 100, 250, 500, and 1000 ppm concentrations of BaTiO3 nanoparticles as inhibitors in 0.5 M HCl and 0.5 M sulphamic medium.

2.9.2 Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS) Measurements
The PDP and EIS measurements were done using an electrochemical workstation (CH-660E) three-electrode configuration with a metal sample (1 cm2) serving as the working electrode, a calomel electrode serving as the reference electrode, and a platinum electrode serving as the counter electrode then immersed in various inhibitor concentrations in 0.5 M HCl and 0.5 M Sulphamic medium.
In general, polarization measurements (PDP) are employed to examine the corrosion of metals in an acid medium. The working electrode was subjected to a potential sweep and the related current response was measured at the same time. The material was polarized cathodically (- 250 mV) and anodically (+250 mV), with a 10 mVs-1 scan rate. From the extrapolation of Tafel slopes, different Tafel parameters like the corrosion current density (icorr) were calculated for the inhibited and inhibitor-free conditions. Based on the obtained corrosion current density the inhibition efficiency (η%) was determined using Equation (5).



Where icorr(blank) and icorr(inh) represent the corrosion current densities (µAcm-2) in the absence and presence of the inhibitor respectively.
For the EIS measurements, a steady-state open-circuit potential was recorded and a frequency range of 100 kHz to 0.1 Hz with an amplitude of 0.005 V was set. Before the potential sweep, the electrode was left in the relevant solution under an open circuit condition (OCP) for 400 seconds to ensure the achievement of a steady free corrosion potential (Ecorr) and was then measured. Using the Z-imp simulation tool, the experimental results fitted to the Randles electrical circuit model R(QR) yielded the impedance parameters. Each concentration was performed three times under identical circumstances to get a consistent and reliable value. Inhibition efficacy η% was defined using the equation (6).



Where, Rp(inh) and Rp(blank) are polarization resistances in the presence and absence of inhibitor, respectively.


3.0 Results and Discussion
3.1 Qualitative phytochemical screening
The results of qualitative screening are given in Table 1. These results are in good agreement with the literature.
Table 1. Results of phytochemical screening of aqueous leaf extract
Constituent Test Result Constituent Test Result
Alkaloids Mayer's reagent test + Tannins and Phenolic compounds Lead acetate test +
Wagner's reagent test + Killer-Killiani test +
Hager's reagent test - Ferric chloride test +
Carbohydrates Molish's test + Saponins Froth test +
Barfoed's test + Proteins and Amino acids Ninhydrin test -
Reducing sugars Fehling's test - Biuret test -
Benedict's test - Triterpenoids and Steroids Salwonski test -
Flavanoids Alkaline reagent test + Libermann and Burchard's test -
Lead acetate test + Carboxylic acids Sodium bicarbonate test -
Glycoside Legal's test + Ester test -
Bomtrager's test +
Note: +: Present, -: Absent













3.2 Crystal structure:

Fig. 1 PXRD pattern of BaTiO3 NPs
The PXRD pattern of BaTiO3 is presented in Fig. 1. Initially, the BaTiO3 nano-powder was investigated using XRD. XRD is a powerful technique commonly utilized to characterize nanomaterials to investigate crystalline properties, including the crystalline phases, the corresponding planes, the average crystalline sizes, and many other parameters. XRD pattern is represented in Fig. 4. The peaks at 22.25°, 31.55°, 38.93°, 45.26°, 50.96°, 56.23°, and 65.9° were ascribed to (001), (110), (111), (200), (210), (211) and (220) plane respectively. The intense and narrow single diffraction peaks confirm the formation of a single phase and agree with the standard JCPDS file for BaTiO3 (JCPDS No. 74-1962). It has a cubic structure with space group Pm-3m (no. 221). The X-ray diffraction pattern shows that the synthesized product is single-phase, well-crystallized, and tetragonal BaTiO3. The size of BaTiO3 crystallites recorded was estimated by the Debye-Scherrer equation D= k λ/ β Cos θ
Where k is the Scherrer constant 0.89, ¬ λ denotes the wavelength of the X-ray source, β denotes the full width at half maxima (FWHM), and ¬ θ denotes the Bragg's diffracted angle. D was found to be 43 nm.
The dislocation density δ was formulated by the equation ρ= 1/D2 and was found to be 5.41 × 10¹⁰ cm⁻². The average lattice strain ϵ was calculated using ϵ = β/4 Cos θ and was found to be 0.0493 or 4.93 %.



3.3 FTIR spectroscopy

Fig. 2: FTIR spectrum of BaTiO3 NPs

In analyzing the FTIR spectrum of BaTiO3 NPs, key transmittance bands were identified at 469.5 cm⁻¹, 850.4 cm⁻¹, 937.7 cm⁻¹, and 1536.4 cm⁻¹, reflecting specific vibrational modes associated with the material. The band at 469.5 cm⁻¹ is likely related to the bending vibrations of the Ti-O bonds, which are essential for the crystal structure of BaTiO3. The peak at 850.4 cm⁻¹ may indicate lattice vibrations typical of the tetragonal symmetry that contributes to the ferroelectric properties of the material. Meanwhile, the band at 937.7 cm⁻¹ is associated with the stretching vibrations of the Ti-O bonds, further highlighting the role of the titanium-oxygen framework. The higher frequency band at 1536.4 cm⁻¹ may correspond to overtone or combination vibrations, suggesting complex interactions within the lattice. Overall, these bands collectively underscore the structural integrity and bonding characteristics of BaTiO3 nanoparticles, indicating the presence of essential functional groups and interactions that are crucial for their applications in electronics and materials science.



3.4 UV-Vis spectroscopy
A plot of (αEg)¹/² versus Eg for BaTiO3 NPs is shown in Fig. 3. Using the Wood-Tauc method, the band gap energy for both samples was estimated to be approximately 3.4 eV, which aligns well with the reported values in the literature.


Fig. 3: Band gap calculation in BaTiO3 NPs

3.5 Surface Morphology and Elemental composition
The SEM analysis of BaTiO3 synthesized via the SCS method, as illustrated in Fig. 4(a), reveals the presence of spherical particles with non-uniform thickness. This microstructure is characteristic of materials produced through SCS, arising from the interplay of rapid exothermic combustion reactions, significant hot gas evolution, and the propagation of combustion waves driven by local temperature gradients. The gas evolution contributes to the development of a highly porous structure, while the rapid solid-phase formation within the combustion wave enhances the material's nanocrystallinity.
EDAX analysis (Fig. 4(b)) identified the primary elemental composition of Ba, Ti, and O. Further, Fig. 4(c) presents a TEM image of the sample, clearly indicating that the particles exhibit nearly spherical and cubic morphologies, albeit with non-uniform characteristics.








Fig. 4: (a) SEM image at a resolution of 50 µm, (b) EDAX, and TEM image at a resolution of 100 nm of BaTiO3 NPs

3.6 BET surface area
Multi point BET surface area of BaTiO3 NPs was recorded to be 71.654 m²/g. This substantial surface area is indicative of the high degree of porosity and fine particle size of the nanoparticles, which are crucial for enhancing their reactivity and functionality across various applications.






3.7 Antioxidant activity
3.7.1 DPPH free radical scavenging activity

Fig. 5: The BaTiO3 NPs demonstrated a concentration-dependent DPPH scavenging activity. The values are presented as mean ± SE (n = 3).

The BaTiO₃ NPs exhibited concentration-dependent scavenging activity against DPPH. At a concentration of 400 µg, the NPs scavenged 53.2 ± 4.5% of DPPH (Fig. 5).

3.7.2 DPPH activity of TLC separated sample


Fig. 6: DPPH activity on the TLC plate was assessed by spraying methanolic DPPH solution onto the dried plates. (A) Control (TLC plate alone), (B) DPPH only, and (C) DPPH with BaTiO₃ NPs (5 µg). The clearance of the violet color indicates the scavenging activity

Additionally, the TLC plate containing only DPPH appeared purple, while the TLC plate loaded with BaTiO3 NPs displayed a purple background with a yellow clearing zone (Fig. 6).

3.7.3 Reducing power assay (FRAP)

Fig. 7: The BaTiO₃ NPs exhibited concentration-dependent FRAP activity. The values are presented as mean ± SE (n = 3).

The FRAP assay is used to evaluate the overall antioxidant potential of compounds by measuring their electron-donating capacity, which reduces Fe³⁺ to Fe²⁺. In this assay, antioxidants in the sample aid in the reduction process, and a spectrophotometer is utilized to quantify the resulting ferrous ions. An increase in optical density (OD) reflects higher FRAP activity. BaTiO₃ NPs exhibited significant FRAP activity (Fig. 7).











3.7.4 Seed germination studies
.
Fig. 8: The percentage germination of Fenugreek seeds in the presence of BaTiO₃ NPs was evaluated at concentrations of 1 mM, 2.5 mM, and 5 mM.

Fenugreek seeds treated with BaTiO₃ NPs significantly increased germination rates compared to the control. The BaTiO₃ treatments were effective, with the 5 mM concentration achieving a 98% germination rate (Fig. 8). The BaTiO₃ NPs demonstrated a moderate enhancement in germination.



Fig. 9: The effect of BaTiO₃ NPs on root and shoot development was analyzed at different concentrations: b) 1 mM, c) 2.5 mM, and d) 5 mM, in comparison to a) the control. Significant variations were observed across these concentrations, highlighting the impact of BaTiO₃ on plant growth parameters.

To evaluate the effects of BaTiO3 NPs, the root and shoot lengths of all seedlings were measured after 14 days. The results indicated that BaTiO₃ NPs significantly influenced the growth of Fenugreek plants (Fig. 9 and Table 2). The treatments showed varying effects, with the 5 mM concentration producing the highest shoot length of 5 ± 0.2 cm, but the lowest root length of 4.0 ± 0.2 cm (Fig. 9, Table 2). These findings suggest that nanoparticle treatments can enhance plant growth, with optimal outcomes depending on the concentration and type of nanoparticle.
A two-way ANOVA was conducted, revealing significant differences at concentrations b) 2.5 mM and c) 5 mM (P > 0.05), while no significant differences were found between a) the control and b) 1 mM (P > 0.05). Data are presented as Mean ± SD, N = 10.

Table 2: Effect of BaTiO3 NPs on root and shoot length at different concentrations.

Sample Shoot length in cm Root length in cm Root: Shoot Ratio
Control 4±0.2*ab 2±0.1ab 1.3:1
BaTiO3 (1 mM) 5±0.3* 2.2±0.1a 1.5:1
BaTiO3 (2.5 mM) 5±0.2a 4±0.2a 1.8:1
BaTiO3 (5 mM) 6±0.4a 5±0.3a 1.6:1

The study demonstrated that BaTiO3 NPs influence root and shoot growth in Fenugreek plants, with varying root-to-shoot ratios. This ratio indicates how biomass is allocated between the root system and the above-ground parts of the plant (shoots). While an optimal root-to-shoot ratio varies by species and conditions, a balanced ratio is typically around 1:1 to 2:1 (Table 2). The findings suggest that these nanoparticle concentrations are effective in supporting both root and shoot growth, which can enhance overall plant stability and nutrient uptake. This highlights the potential of NPs to optimize plant resource allocation, essential for water and nutrient uptake, growth, and productivity.
Additionally, tests for chlorophyll a, chlorophyll b, and total chlorophyll levels were conducted to assess photosynthetic pigment content, which is crucial for evaluating plant health, photosynthetic efficiency, and responses to environmental stresses. The results showed varying effects of MoO₃ NPs on chlorophyll content in Fenugreek plants. Chlorophyll a, chlorophyll b, and total chlorophyll levels generally increased with higher nanoparticle concentrations, suggesting a stimulatory effect on chlorophyll biosynthesis and/or stabilization. Notably, at 2.5 mM and 5 mM concentrations, both chlorophyll a and b levels significantly increased compared to the control. This enhancement in chlorophyll content correlates with the observed improvements in shoot and root lengths, indicating better photosynthetic efficiency and plant vigor. BaTiO₃ NPs also showed a trend of increasing chlorophyll content with higher concentrations, with the 5 mM concentration yielding the highest chlorophyll levels among the treatments (Table 3).
These findings suggest that BaTiO3 NPs can enhance chlorophyll production in Fenugreek plants, likely through mechanisms that promote chlorophyll synthesis or protect chlorophyll molecules from degradation. Optimal concentrations for promoting chlorophyll biosynthesis appear to be around 2.5 mM to 5 mM.

Table 3: Chlorophyll content of the BaTiO3 NPs (Mean±SD, N=10) treated plants at different concentrations.
Treatment Chlorophyll a Chlorophyll b Total Chlorophyll
(µg/mL)
Control 4.65±0.24 2.34±0.18 6.8±0.34
BaTiO3 (1 mM) 4.97 ± 0.39 2.76 ± 0.22 7.7 ± 0.52
BaTiO3 (2.5 mM) 5.49 ± 0.28 3.59 ± 0.4 9.09 ± 0.54
BaTiO3 (5 mM) 5.51 ± 0.43 3.42 ± 0.31 8.89 ± 0.68

Fenugreek seeds treated with BaTiO₃ NPs demonstrated improved germination, with the highest rate of 98% observed at 2.5 mM. BaTiO3 at 5 mM yielded the shoot length (6 ± 0.4 cm) and root length (5 ± 0.3 cm). BaTiO3 at 2.5 mM and 5 mM achieved balanced root-to-shoot ratios of 1.5:1 and 1.8:1, respectively, which enhanced plant stability and nutrient uptake. BaTiO3 increased chlorophyll content, with 2.5 mM and 5 mM significantly enhancing chlorophyll a and b levels, indicating improved photosynthetic efficiency.






3.8 Electrochemical studies
3.8.1 Potentiodynamic Polarization (PDP) studies



Figure 10: Potentiodynamic polarization graphs for MS corrosion control at 298 K, with different BaTiO3 concentrations in 0.5 M HCl and 0.5 M Sulphamic acid medium.

Figure 2, depicts the polarization (PDP) studies at 298 K using the electrochemical approach to examine the corrosion response of BaTiO3 on MS in 0.5 M HCl and 0.5 M sulphamic medium. The potential is applied to the metal surface, and its current response is assessed by sweeping the potential constantly while monitoring the resulting current. The PDP curves, help us to measure the corrosion current density (icorr), corrosion potential (Ecorr), anodic slope (βa), cathodic slope (-βc), and corrosion inhibition efficiency (η%) all the data are given in Table 4. The polarization curve shown in Figures 10 (a) and (b) explains anodic curves showing metal oxidation, whereas cathodic curves show the evolution of H2 in an acidic medium. A kinetic barrier effect, most likely caused by partial disintegration of the oxide layer, along the anodic curve is observed between -0.45 to -0.35 for 0.5 M sulphamic medium (Fig. 2(b)).





Table 4: PDP parameters (mean ± 1 standard deviation) for MS corrosion control at 298 K with different BaTiO3 concentrations in 0.5 M HCl and 0.5 M Sulphamic acid medium.
Temp
(K) BaTiO3
(ppm) Ecorr
(V) icorr(10-4)
(Acm-2) -βc
(Vdec-1) +βa
(Vdec-1) CR
(mpy) η%

0.5 M HCl



298 Blank -0.5254 12.44 5.911 7.445 562.9 -
100 -0.5170 9.990 5.695 7.682 452.1 19.69±0.93
250 -0.4949 8.187 6.355 8.300 370.5 34.88±0.85
500 -0.4995 5.22 7.086 9.441 236.5 58.63±0.92
750 -0.5118 4.789 7.313 7.555 216.7 61.50±0.98
1000 -0.5209 3.771 7.220 8.035 171.0 69.50±0.89
0.5 M Sulphamic acid



298 Blank -0.5117 10.82 6.589 5.601 489.7 -
100 -0.5089 8.159 6.899 6.348 369.3 24.59±1.02
250 -0.5095 7.219 6.654 6.356 326.7 33.28±1.65
500 -0.5238 5.921 7.557 6.825 268.0 45.27±1.35
750 -0.5099 5.199 7.929 7.750 235.3 51.95±1.55
1000 -0.4954 3.961 8.257 9.830 179.3 63.39±0.97

Table 1 data reveals, in contrast to the blank, that the potential value (Ecorr) moves towards less negative values, the reaction being more controlled by anodic than cathodic reactions. The current density (icorr) values also shifted to lower (both the anodic and cathodic) current densities when a BaTiO3 inhibitor was added to both acids. A mixed-type inhibitor shifts the corrosion potential (Ecorr) value by less than ±85 mV compared to the blank solution. The plots obtained for the BaTiO3 inhibitor showed that it acted as a mixed-type inhibitor, indicating that both cathodic and anodic reactions were retarded by the addition of the BaTiO3 inhibitor. This change implies that the BaTiO3 inhibitor suppresses both the processes (anodic and cathodic reactions). The reduction in the corrosion rate (CR) is implied by the drop in corrosion current density (icorr) and an increase in the inhibition efficiency. Thus BaTiO3 inhibitor molecules form a shielding layer over the MS surface.
On comparing the metal dissolution rate it was found that the CR was comparatively more in the HCl medium than in sulphamic medium. Also, on comparing the efficiencies it was found that BaTiO3 Nps acts as a good inhibitor in HCl medium (69.5 %).
3.8.2 Electrochemical impedance spectroscopic (EIS) studies











Figure 11: Nyquist graphs for MS corrosion control at 298 K, with different BaTiO3 concentrations in 0.5 M HCl and 0.5 M Sulphamic acid medium.

Figure 11 (a) and (b) displays the impedance spectra of the MS electrode at 298 K for its corrosion in 1 M HCl and 0.5 M sulphamic medium in the presence and absence of various BaTiO3 inhibitor concentrations shown by Nyquist plots. The Nyquist plot is characterized by one capacitive loop appear in the high-frequency region. As depicted in Figure 11, the Nyquist plots indicated that MS resistance values in the presence of inhibitors increased when compared to untreated solutions. The capacitive loop formed is associated with resistive corrosion and film formation on the MS surface.
Using Z SimpWin software the Nyquist spectra obtained were fit to RCR equivalent circuits to obtain EIS parameters in the absence and presence of the studied inhibitor. Table 5 presents the EIS parameters, determined by fitting the plot to the equivalent circuit. The circuit shows (Rs) solution resistance and (Cdl) double layer capacitance of the corrosion film that has formed on the MS that are computed using the CPE parameters (n and YO). It can be seen in Table 5 that the Rp value increases with BaTiO3 inhibitor concentrations. This might have been caused by iron dissolution occurring continuously on the MS surface. However, when the inhibitor was added, a protective layer developed with more compact characteristics, and the overall iron dissolution was reduced, resulting in a lowering of surface heterogeneity.
Table 5: EIS parameters (mean ± 1 standard deviation) for variation of concentration of CNG inhibitor at three different temperatures
Temp
(K) BaTiO3
(ppm) Rs
(Ω cm2) Rp
(Ω cm2) Yo(10-4) n
Cdl
(µFcm2) η
(%)
0.5 M HCl


298 Blank 3.98 17.61 1.712 0.9238 106.1 -
100 4.677 23.83 1.655 0.8612 67.47 26.10±1.10
250 4.165 30.72 1.625 0.8450 61.47 42.67±0.90
500 3.957 41.16 1.219 0.8746 57.06 57.21±0.85
750 3.836 42.85 1.255 0.8672 56.38 58.90±1.25
1000 3.781 59.63 0.920 0.8818 45.79 70.46±1.05
0.5 M Sulphamic acid



298 Blank 8.842 19.87 4.29 0.8198 150.5 -
100 7.797 25.36 2.841 0.8229 98.27 21.64±1.28
250 7.751 29.44 3.105 0.7447 62.09 32.50±1.54
500 6.216 35.29 1.092 0.8506 41.35 43.69±1.89
750 5.149 42.17 1.085 0.7730 22.30 52.88±1.54
1000 3.522 52.77 1.058 0.7340 16.14 62.34±0.98
, Claims:Claims:
1. Claim 1: A method for synthesizing BaTiO₃ NPs utilizing an exothermic combustion process, wherein the process employs barium nitrate, titanium tetra-n-butyl titanate, and a green reducing agent derived from Ipomoea purpurea flower extract.
2. Claim 2: BaTiO₃ NPs characterized by a cubic crystalline structure, as confirmed by X-ray diffraction, and exhibiting a crystallite size of approximately 43 nm and a BET surface area of 71.654 m²/g.
3. Claim 3: BaTiO₃ NPs demonstrating antioxidant properties, specifically a DPPH scavenging activity of at least 53.2% at a concentration of 400 µg.
4. Claim 4: A composition comprising BaTiO₃ NPs effective in enhancing seed germination rates, achieving at least a 98% germination rate at a concentration of 5 mM.
5. Claim 5: BaTiO₃ NPs serving as an anti-corrosive agent, with a corrosion inhibition efficiency of at least 69.5% in acidic environments, specifically in 0.5 M HCl.
6. Claim 6: A formulation or product incorporating BaTiO₃ NPs for applications in biomedical, agricultural, and energy technologies, leveraging their antioxidant, growth-promoting, and anti-corrosive properties.

Documents