Search Results (27)

The present study demonstrates the synthesis of phase pure hematite (α-Fe₂O₃) nanoparticles (NPs) using collagen protein and calcium carbonate extracted from eggshell membranes and eggshells, respectively, as organic additives. To test the influence of organic additives on the quality of the resulting NPs, the amount of eggshell powder was varied between 1 to 5 g in aqueous iron nitrate solution. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and RAMAN analysis confirmed the formation of hematite NPs without any impurities. FTIR spectra revealed the presence of polyphenolic constituents on the surface of the resulting NPs as stabilizers, which may potentially be responsible for the observed antioxidant and antibacterial properties. Furthermore, the stable phase and the presence of low defects divulged the high hardness value (~983 HV) and fracture toughness (8.59 MPa m^1/2), which can be exploited for bone implantation. The FE-SEM results demonstrate the formation of spherical particles, which are well-separated NPs. The results of a biodegradation study which was carried out in phosphate-buffered saline (PBS) revealed that the as-prepared NPs retained their hardness even after 72 h of soaking. These prepared NPs showed 95% radical scavenging activity (RSA) and were good carriers against S. aureus bacteria. Moreover, the SEM images of the mineralization of iron oxide NPs confirmed the formation of new bone. After 5 weeks, all pores were filled, and the minerals were deposited on the surfaces of the scaffolds. Full article

Semiconducting nanomaterials based heterogeneous photocatalysis represent a low-cost, versatile technique for environmental remediation, including pollution mitigation, energy management and other environmental aspects. Herein, we demonstrate the syntheses of various heterogeneous photocatalysts based on highly reduced graphene oxide (HRG) and vanadium oxide (VO_x)-based nanocomposites (HRG–VO_x). Different shapes (rod, sheet and urchin forms) of VO_x nanoparticles were successfully fabricated on the surface of HRG under solvo-/hydrothermal conditions by varying the amount of water and ethanol. The high concentration of water in the mixture resulted in the formation of rod-shaped VO_x nanoparticles, whereas increasing the amount of ethanol led to the production of VO_x sheets. The solvothermal condition using pure ethanol as solvent produced VO_x nano-urchins on the surface of HRG. The as-prepared hybrid materials were characterized using various spectroscopic and microscopic techniques, including X-ray diffraction, UV–vis, FTIR, SEM and TEM analyses. The photocatalytic activities of different HRG–VO_x nanocomposites were investigated for the photodegradation of methylene blue (MB) and methyl orange (MO). The experimental data revealed that all HRG–VO_x composite-based photocatalysts demonstrated excellent performance toward the photocatalytic degradation of the organic dyes. Among all photocatalysts studied, the HRG–VO_x nanocomposite consisting of urchin-shaped VO_x nanoparticles (HRG–VO_x-U) demonstrated superior photocatalytic properties towards the degradation of dyes. Full article

The utilization of heterogeneous catalysts during the production of biodiesel potentially minimize the cost of processing due to the exclusion of the separation step. The (X wt%)Ni–ZrO₂ (where X = 10, 25 and 50) catalysts prepared through a hydrothermal process were tested for the production of biodiesel by the transesterification of waste cooking oil (WCO) with methanol. The influences of various reaction parameters were systematically optimized. While the physicochemical characteristics of the as-synthesized catalysts were examined using numerous techniques such as FTIR, XRD, TGA BET, EDX, SEM, and HRTEM. Among all the catalysts, (10 wt%)Ni–ZrO₂ exhibited high surface area when compared to the pristine ZrO₂, (25 wt%)Ni–ZrO₂ and (50 wt%)Ni–ZrO₂ nanocatalysts. It may have influenced the catalytic properties of (10 wt%)Ni–ZrO_2, which exhibited maximum catalytic activity with a biodiesel production yield of 90.5% under optimal conditions. Such as 15:1 methanol to oil molar ratio, 10 wt% catalysts to oil ratio, 8 h reaction time and 180 °C reaction temperature. Furthermore, the recovered catalyst was efficiently reused in several repeated experiments, demonstrating marginal loss in its activity after multiple cycles (five times). Full article

Hydrogel electrolytes for energy storage devices have made great progress, yet they present a major challenge in the assembly of flexible supercapacitors with high ionic conductivity and self-healing properties. Herein, a smart self-healing hydrogel electrolyte based on alginate/poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (alginate/PEDOT:PSS)(A/P:P) was prepared, wherein H₂SO₄ was employed as a polymeric initiator, as well as a source of ions. PEDOT:PSS is a semi-interpenetrating network (IPN) that has been used in recent studies to exhibit quick self-healing properties with the H₂SO₃ additive, which further improves its mechanical strength and self-healing performance. A moderate amount of PEDOT:PSS in the hydrogel (5 mL) was found to significantly improve the ionic conductivity compared to the pure hydrogel of alginate. Interestingly, the alginate/PEDOT:PSS composite hydrogel exhibited an excellent ability to self-heal and repair its original composition within 10 min of cutting. Furthermore, the graphite conductive substrate-based supercapacitor with the alginate/PEDOT:PSS hydrogel electrolyte provided a high specific capacitance of 356 F g⁻¹ at 100 mV/s g⁻¹. The results demonstrate that the A/P:P ratio with 5 mL PEDOT:PSS had a base sheet resistance of 0.9 Ω/square. This work provides a new strategy for designing flexible self-healing hydrogels for application in smart wearable electronics. Full article

Green syntheses of metallic nanoparticles using plant extracts as effective sources of reductants and stabilizers have attracted decent popularity due to their non-toxicity, environmental friendliness and rapid nature. The current study demonstrates the ecofriendly, facile and inexpensive synthesis of silver nanoparticles (AP-AgNPs) using the extract of aerial parts of the Anthemis pseudocotula Boiss. plant (AP). Herein, the aerial parts extract of AP performed a twin role of a reducing as well as a stabilizing agent. The green synthesized AP-AgNPs were characterized by several techniques such as XRD, UV-Vis, FT-IR, TEM, SEM and EDX. Furthermore, the antimicrobial and antibiofilm activity of as-prepared AP-AgNPs were examined by a standard two-fold microbroth dilution method and tissue culture plate methods, respectively, against several Gram-negative and Gram-positive bacterial strains and fungal species such as Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), multidrug-resistant Pseudomonas aeruginosa (MDR-PA) and Acinetobacter baumannii (MDR-AB), methicillin-resistant S. aureus (MRSA) and Candida albicans (C. albicans) strains. The antimicrobial activity results clearly indicated that the Gram-negative bacteria MDR-PA was most affected by AgNPs as compared to other Gram-negative and Gram-positive bacteria and fungi C. albicans. Whereas, in the case of antibiofilm activity, it has been found that AgNPs at 0.039 mg/mL, inhibit biofilms formation of Gram-negative bacteria i.e., MDR-PA, E. coli, and MDR-AB by 78.98 ± 1.12, 65.77 ± 1.05 and 66.94 ± 1.35%, respectively. On the other hand, at the same dose (i.e., 0.039 mg/mL), AP-AgNPs inhibits biofilm formation of Gram-positive bacteria i.e., MRSA, S. aureus and fungi C. albicans by 67.81 ± 0.99, 54.61 ± 1.11 and 56.22 ± 1.06%, respectively. The present work indicates the efficiency of green synthesized AP-AgNPs as good antimicrobial and antibiofilm agents against selected bacterial and fungal species. Full article

This work demonstrates hydrazine electro-oxidation and sensing using an ultrathin copper oxide nanosheet (CuO-NS) architecture prepared via a versatile foam-surfactant dual template (FSDT) approach. CuO-NS was synthesised by chemical deposition of the hexagonal surfactant Brij^®58 liquid crystal template containing dissolved copper ions using hydrogen foam that was concurrently generated by a sodium borohydride reducing agent. The physical characterisations of the CuO-NS showed the formation of a two-dimensional (2D) ultrathin nanosheet architecture of crystalline CuO with a specific surface area of ~39 m²/g. The electrochemical CuO-NS oxidation and sensing performance for hydrazine oxidation revealed that the CuO nanosheets had a superior oxidation performance compared with bare-CuO, and the reported state-of-the-art catalysts had a high hydrazine sensitivity of 1.47 mA/cm² mM, a low detection limit of 15 μM (S/N = 3), and a linear concentration range of up to 45 mM. Moreover, CuO-NS shows considerable potential for the practical use of hydrazine detection in tap and bottled water samples with a good recovery achieved. Furthermore, the foam-surfactant dual template (FSDT) one-pot synthesis approach could be used to produce a wide range of nanomaterials with various compositions and nanoarchitectures at ambient conditions for boosting the electrochemical catalytic reactions. Full article

Nanomedicine has been used as a precise treatment for many diseases. The advantage of using nanodrugs is that they have more permeability and less toxicity to cells, which enhances the drug delivery system. Graphene is well known for its potential biological applications in drug, food, and pharma industries. This study aimed to assess the productivity and potentiality of nitrogen-doped graphene (NDG) and to evaluate their anticancer, antimicrobial, and biofilm inhibition activity. Nitrogen-doped graphene was synthesized by using a one-pot facile synthesis of NDG, wherein the NDG was prepared by the reduction of graphene oxide (GO) in the presence of hydrazine hydrate as a reducing agent, while ammonium hydroxide was used as a source of nitrogen on the surface of graphene. As-synthesized NDG was characterized by various characterization techniques such as UV-Vis, FT-IR, XRD, XPS, TEM, and N₂ sorption studies analysis. Antimicrobial, anticancer, and biofilm inhibition assays were performed by standard protocols. N-doped graphene (NDG) showed better activity against Gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtillis, Streptococcus pneumoniae, and Streptococcus mutans (p ≤ 0.05), whereas there was no activity against Gram-negative strains in Klebsiella pneumoniae and Pseudomonas aeruginosa. Biofilm inhibition was also improved with NDG compared to the standard ampicillin. NDG showed better results in both MCF-7 and Hela cell lines with IC₅₀ of 27.15 µg/mL and 30.85 µg/mL, respectively. In conclusion, NDG has the best ability for use as a biomolecule, and research studies focusing on proteomics, metabolomics, and in vivo studies are needed to increase the impact of NDG in the drug and pharma industry. Full article

Plant extract-based green synthesis of metal nanoparticles (NPs) has become a popular approach in the field of nanotechnology. In this present investigation, silver nanoparticles were prepared by an efficient and facile approach using Juniperus procera extract as a bioreducing and stabilizing agent. The as-synthesized silver nanoparticles (JP-AgNPs) were characterized by several characterization techniques such as UV–Vis, XRD, FT-IR, HR-TEM, and EDX analysis. The XRD analysis evidently confirms that the as-synthesized Ag nanoparticles (NPs) from Juniperus procera plant extract (JP-AgNPs) are crystalline in nature. FT-IR analysis confirms that the plant extract plays a dual role as a bioreducing and capping agent, while HR-TEM revealed the spherical morphology of as-synthesized JP-AgNPs with the size of ~23 nm. Furthermore, the synthesized JP-AgNPs were evaluated for antibacterial properties against several bacterial and fungal strains such as Staphylococcus aureus (ATCC 12228), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Proteus mirabilis (ATCC 4753), Cryptococcus neoformans (ATCC 16620), and Candida albicans (ATCC 885-653). The JP-AgNPs displayed an efficient mean zone of inhibition (MZI) at 50.00 µL for bacterial associated with fungal pathogens than the plant extract. Mainly, MZI values against microbial pathogens were as follows; E. coli (17.17 ± 0.72 mm), P. mirabilis (14.80 ± 0.17 mm), and C. albicans (14.30 ± 0.60 mm), whereas JP-AgNPs showed moderate activity against P. aeruginosa (11.50 ± 0.29 mm) and C. neoformans (9.83 ± 0.44 mm). Notably, the tested JP-AgNPs have displayed almost similar antimicrobial activities with that of standard antimicrobial drugs, such as streptomycin and nystatin. The enhanced antimicrobial activity of JP-AgNPs can be ascribed to the quality of resultant NPs including, uniform size, shape, and aqueous colloidal stability of nanoparticles. Full article

The present work was carried out to synthesize bismuth ferrite (BFO) nanoparticles by combustion synthesis, and to evaluate the photocatalytic activity of synthesized bismuth ferrite nanoparticles against cefixime trihydrate. BFO nanoparticles were successfully synthesized using bismuth (III) nitrate and iron (III) nitrate by a combustion synthesis method employing different types of fuels such as maltose, succinic acid, cinnamic acid, and lactose. The effects of the different types of fuels on the morphology and size of the bismuth ferrite nanoparticles were investigated. Characterization of the as-obtained bismuth ferrite nanoparticles was carried out by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-Dispersive Spectroscopy (EDS), N₂-sorption analysis, Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet-visible (UV–vis) spectroscopy. Photoluminescence studies were also carried out for the various bismuth ferrite nanoparticles obtained. Degradation of cefixime trihydrate was investigated under sunlight to evaluate the photocatalytic properties of the bismuth ferrite nanoparticles, and it was found that the bismuth ferrite nanoparticles followed first-order degradation kinetics in solar irradiation in the degradation of antibiotic, cefixime trihydrate. Full article

In this work, ZnO nanocrystals (NCs) have been effectively synthesized by a simple, efficient and cost-effective method using coconut husk extract as a novel fuel. The synthesized NCs are characterized by UV-Vis, XRD, FT-IR, SEM, EDX, Raman and PL studies. The obtained ZnO were found to be UV-active with a bandgap of 2.93 eV. The X-ray diffraction pattern confirms the crystallinity of the ZnO with hexagonally structured ZnO with a crystallite size of 48 nm, while the SEM analysis reveals the hexagonal bipyramid morphology. Photocatalytic activities of the synthesized ZnO NCs are used to degrade methylene blue and metanil yellow dyes. Full article

The synthesis of 14-aryl 14H-dibenzo[a,j]xanthenes is achieved by a simple condensation reaction between β-naphthol with aryl or alkyl aldehydes in an effective synergetic catalytic system created by combining basic bleaching earth clay and PEG-600. The advantages of the present method include catalyst recyclability, superior product yield, a shorter reaction time and the avoidance of hazardous reagents. Synthesized xanthene derivatives were also screened for their antibacterial activity against Staphylococcus aureus (MTCC 96) and Pseudomonas aeruginosa (Wild). Full article

Catalytic efficacy of metal-based catalysts can be significantly enhanced by doping graphene or its derivatives in the catalytic protocol. In continuation of previous work regarding the catalytic properties of highly-reduced graphene oxide (HRG), graphene-oxide (GO) doped mixed metal oxide-based nanocomposites, herein we report a simple, straightforward and solventless mechanochemical preparation of N-doped graphene (NDG)/mixed metal oxide-based nanocomposites of ZnO–MnCO₃ (i.e., ZnO–MnCO₃/(X%-NDG)), wherein N-doped graphene (NDG) is employed as a dopant. The nanocomposites were prepared by physical milling of separately fabricated NDG and ZnO–MnCO₃ calcined at 300 °C through eco-friendly ball mill procedure. The as-obtained samples were characterized via X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), Raman, Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and surface area analysis techniques. To explore the effectiveness of the obtained materials, liquid-phase dehydrogenation of benzyl alcohol (BOH) to benzaldehyde (BH) was chosen as a benchmark reaction using eco-friendly oxidant (O₂) without adding any harmful surfactants or additives. During the systematic investigation of reaction, it was revealed that the ZnO–MnCO₃/NDG catalyst exhibited very distinct specific-activity (80 mmol/h.g) with a 100% BOH conversion and <99% selectivity towards BH in a very short time. The mechanochemically synthesized NDG-based nanocomposite showed remarkable enhancement in the catalytic performance and increased surface area compared with the catalyst without graphene (i.e., ZnO–MnCO₃). Under the optimum catalytic conditions, the catalyst successfully transformed various aromatic, heterocyclic, allylic, primary, secondary and aliphatic alcohols to their respective ketones and aldehydes with high selectively and convertibility without over-oxidation to acids. In addition, the ZnO–MnCO₃/NDG was also recycled up to six times with no apparent loss in its efficacy. Full article

In recent years, the development of green mechanochemical processes for the synthesis of new catalysts with higher catalytic efficacy and selectivity has received manifest interest. In continuation of our previous study, in which graphene oxide (GRO) and highly reduced graphene oxide (HRG) based nanocomposites were prepared and assessed, herein, we have explored a facile and solvent-less mechanochemical approach for the synthesis of N-doped graphene (NDG)/mixed metal oxide (MnCO₃–ZrO₂) ((X%)NDG/MnCO₃–ZrO₂), as the (X%)NDG/MnCO₃–ZrO₂ nano-composite was synthesized using physical grinding of separately synthesized NDG and pre-calcined (300 °C) MnCO₃–ZrO₂ via green milling method. The structures of the prepared materials were characterized in detail using X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), Raman, Thermogravimetric analysis (TGA), and N₂ adsorption-desorption isotherm analysis. Besides, the obtained nanocomposites were employed as heterogeneous oxidation catalyst for the alcohol oxidation using green oxidant O₂ without involving any surfactants or bases. The reaction factors were systematically studied during the oxidation of benzyl alcohol (PhCH₂OH) as the model reactant to benzaldehyde (PhCHO). The NDG/MnCO₃–ZrO₂ exhibits premium specific activity (66.7 mmol·g⁻¹·h⁻¹) with 100% conversion of PhCH₂OH and > 99.9% selectivity to PhCHO after only 6 min. The mechanochemically prepared NDG based nanocomposite exhibited notable improvement in the catalytic efficacy as well as the surface area compared to the pristine MnCO₃–ZrO₂. Under the optimal circumstances, the NDG/MnCO₃–ZrO₂ catalyst could selectively catalyze the aerobic oxidation of a broad array of alcohols to carbonyls with full convertibility without over-oxidized side products like acids. The NDG/MnCO₃–ZrO₂ catalyst were efficiently reused for six subsequent recycling reactions with a marginal decline in performance and selectivity. Full article

Plant extract of Pulicaria undulata (L.) was used as both reducing agent and stabilizing ligand for the rapid and green synthesis of gold (Au), silver (Ag), and gold–silver (Au–Ag) bimetallic (phase segregated/alloy) nanoparticles (NPs). These nanoparticles with different morphologies were prepared in two hours by stirring corresponding metal precursors in the aqueous solution of the plant extracts at ambient temperature. To infer the role of concentration of plant extract on the composition and morphology of NPs, we designed two different sets of experiments, namely (i) low concentration (LC) and (ii) high concentration (HC) of plant extract. In the case of using low concentration of the plant extract, irregular shaped Au, Ag, or phase segregated Au–Ag bimetallic NPs were obtained, whereas the use of higher concentrations of the plant extract resulted in the formation of spherical Au, Ag, and Au–Ag alloy NPs. The as-prepared Au, Ag, and Au–Ag bimetallic NPs showed morphology and composition dependent catalytic activity for the reduction of 4-nitrophenol (4-NPh) to 4-aminophenol (4-APh) in the presence of NaBH₄. The bimetallic Au–Ag alloy NPs showed the highest catalytic activity compared to all other NPs. Full article

Co_xO_y–manganese carbonate (X%)(Co_xO_y–MnCO₃ catalysts (X = 1–7)) were synthesized via a straightforward co-precipitation strategy followed by calcination at 300 °C. Upon calcination at 500 °C, these were transformed to Co_xO_y–dimanganese trioxide i.e., (X%)Co_xO_y–Mn₂O₃. A relative catalytic evaluation was conducted to compare the catalytic efficiency of the two prepared catalysts for aerial oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using O₂ molecule as a clean oxidant without utilizing any additives or alkalis. Amongst the different percentages of doping with Co_xO_y (0–7% wt./wt.) on MnCO₃ support, the (1%)Co_xO_y–MnCO₃ catalyst exhibited the highest catalytic activity. The influence of catalyst loading, calcination temperature, reaction time, and temperature and catalyst dosage was thoroughly assessed to find the optimum conditions of oxidation of benzyl alcohol (BzOH) for getting the highest catalytic efficiency. The (1%)Co_xO_y–MnCO₃ catalyst which calcined at 300 °C displayed the best effectiveness and possessed the largest specific surface area i.e., 108.4 m²/g, which suggested that the calcination process and specific surface area play a vital role in this transformation. A 100% conversion of BzOH along with BzH selectivity >99% was achieved after just 20 min. Notably, the attained specific activity was found to be considerably larger than the previously-reported cobalt-containing catalysts for this transformation. The scope of this oxidation reaction was expanded to various alcohols containing aromatic, aliphatic, allylic, and heterocyclic alcohols without any further oxidation i.e., carboxylic acid formation. The scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) specific surface area analytical techniques were used to characterize the prepared catalysts. The obtained catalyst could be easily regenerated and reused for six consecutive runs without substantial decline in its efficiency. Full article