Formation Of NPs Research Articles

Deep eutectic solvent as an effective tool for enhanced photocatalytic activity of Cu2S@MoS2 nano-assemblies: A green approach

The scientific world has witnessed the emergence of plethora of green strategies to ameliorate the efficiency of nano-photocatalytic materials for waste water treatment applications. This work, for the first time, highlights the effect of ZnCl2 and urea-based DES on the morphology, electronic band structure and photocatalytic efficiency of Cu2S @MoS2 NPs compared to solvents like water, EDA and DETA. XRD and FT-IR analysis confirmed the formation of NPs and quite significant changes in the pattern of M-S bonds of Cu2S@MoS2 were observed upon variation of solvents. The FE-SEM analysis of NPs prepared in 1:1 composition of DES and water (Cu2S@MoS2 NPs - 1:1) showed entirely distinct nanoflower morphology compared to spherical arrangement shown by NPs prepared using other solvents. As a result, Cu2S@MoS2 NPs - 1:1 showed superior textural properties with a surface area of 89 m2/g in contrast to 7.4, 6.2 and 18 m2/g observed for NPs synthesized in water, EDA and DETA, respectively. Besides, wide band gap of 2.75 eV for Cu2S@MoS2 NPs - 1:1 induced favorable charge carrier recombination kinetics, which played an instrumental role in the degradation of tetracycline hydrochloride (TC) and rhodamine B (RB). Cu2S@MoS2 NPs - 1:1 showed best photocatalytic activity as 97% and 96% of TC and RB was removed after 90 min of visible light irradiation with no significant decline in removal efficiency till 5 cycles. Scavenger studies hinted towards the crucial role of h+ and ⋅ OH in degradation process and a mechanism was proposed accordingly. The superior photocatalytic activity of NPs prepared using DES compared to water and organic solvents showed that the inclusion of DES in synthesis schemes of NPs is an excellent strategy for improving their efficiency towards waste water treatment applications.

Highly selective and sensitive humidity sensor using reduced graphene oxide based iron oxide nanocomposites

For the humidity sensing, rGO/Fe2O3 nanocomposites were synthesized via an ultrasonic-assisted method, utilizing Hummers' and co-precipitation techniques for rGO and Fe2O3 synthesis. XRD analysis confirmed the formation of rGO and rhombohedral Fe2O3 NPs, while SEM revealed varied (rough sheet-like and dense compact) morphologies. UV–VIS spectra indicated characteristic absorption peaks for rGO, Fe2O3 NPs, and their NCs. In addition, FTIR spectra validated graphene oxide reduction and Fe2O3 NPs/NCs formation. Humidity sensing was assessed across 40–80 % RH at varying frequencies (100 Hz-10 kHz), with 100 Hz identified as the optimal frequency due to water molecule polarization limitations at higher frequencies. The rGO/Fe2O3 (70/30) NC exhibited a rapid response recovery time (5 s/10 s) and high sensitivity (2715.541 %), attributed to additional active sites provided by Fe2O3, enhancing water molecule adsorption and sensor sensitivity. The sensors demonstrated long-term stability and repeatability, showcasing promising potential for humidity sensing applications.

Local electric field enhancement in the vicinity of aggregates of Ag, Au, Rb containing nanoparticles in oxide glasses

Local electric field (LEF) distribution near Ag, Au, AgAu NPs synthesized by UV laser or temperature treatments, and near simulated Rb, AgRb, AuRb NPs in oxide glasses, was studied considering aggregates of 10–15 particles - necessary condition for description of optical extinction spectra. For efficient analysis of LEF spatial distributions under different sizes, components, agglomerations of NPs in these aggregates, approach was proposed that enables to obtain dependence of averaged LEF enhancement upon the distance from the nearest particles in aggregate. This approach reproduced enhancement of Er3+ luminescence intensity in zinc-tellurite glass after formation of Ag NPs and showed that average LEF enhancement per hypothetical Rare Earth ion (REI) is largest for aggregates of Ag, less for Rb, lowest for Au NPs. The optimal Ag NPs aggregate was estimated for best LEF enhancement per hypothetical REI. Simulated aggregates of Rb containing NPs demonstrated strong LEF, shifted in a wide range.

Brucine Entrapped Titanium Oxide Nanoparticle for Anticancer Treatment: An In Vitro Study.

Backgroundand Objective. The public's health has been seriously threatened by cervical cancer during recent times. In terms of newly diagnosed cases worldwide, it ranks as the ninth most prevalent malignancy. Multiple investigations have proven that nanoparticles can effectively combat cancer due to their small dimensions and extensive surface area. In the meantime, bioactive compounds which are biocompatible are being loaded onto nanoparticles to promote cancer therapy. The current study investigates the anticancerous potential of Brucine-entrapped titanium oxide nanoparticles (TiO2 NPs) in cervical cancer cell line (HeLa). Materials and Methods. The physiochemical, structural, and morphological aspects of Brucine-entrapped TiO2 NPs were evaluated by UV-visible spectrophotometer, Fourier transform-infrared spectroscopy (FT-IR), dynamic light scattering (DLS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDAX). The cytotoxic effect against the HeLa cell line was assessed using a tetrazolium-based colorimetric assay (MTT), a trypan blue exclusion (TBE) assay, phase contrast microscopic analysis, and a fluorescence assay including ROS and DAPI staining. Furthermore, estimation of antioxidant markers includes catalase (CAT), glutathione (GSH), and superoxide dismutase (SOD). Results. The UV spectrum at 266 nm revealed the formation of TiO NPs. The FT-IR peaks confirmed the effective entrapment of brucine with TiO2 NPs. The average size (100.0 nm) of Brucine-entrapped TiO2 NPs was revealed in DLS analysis. The micrograph of the SEM revealed the formation of ellipsoidal to tetragonal-shaped NPs. The Ti, O, and C signals were observed in EDAX. In MTT assay, Brucine-entrapped TiO2 NPs showed inhibition of cell proliferation in a dose-wise manner and IC50 was noticed at the concentration of 30 µg/mL. The percentage of viable cells gradually reduced in the trypan blue exclusion assay. The phase contrast microscopic analysis of Brucine-entrapped TiO2 NP-treated cells showed cell shrinkage, cell wall deterioration, and cell blebbing. The intracellular ROS level was increased in a dose-wise manner when compared to control cells in ROS staining. The condensed nuclei and apoptotic cells were increased in treated cells, as noted in DAPI staining. In treated cells, the antioxidant markers such as CAT, GSH, and SOD levels were substantially lower compared to the control cells. Conclusion. The synthesized Brucine entrapped TiO2 NPs exhibited remarkable anticancer activity against the HeLa cell line.

Phyto-fabricated ZnO nanoparticles for anticancer, photo-antimicrobial effect on carbapenem-resistant/sensitive Pseudomonas aeruginosa and removal of tetracycline.

Alternanthera sessilis (AS) leaf extract was used to synthesize zinc oxide nanoparticles (ZnO NPs). Bioanalytical characterization techniques such as X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) confirmed the formation of crystalline ZnO NPs with average sizes of 40nm. The AS-ZnO NPs antimicrobial activity was analyzed under dark (D) and white light (WL) conditions. The improved antimicrobial activity was observed against Escherichia coli, Staphylococcus aureus and Bacillus subtilis at the minimal inhibitory concentration (MIC) of 125 and 62.5µg/mL under WL than the D at 125 and 250µg/mL for E. coli, B. subtilis, and Pseudomonas aeruginosa, respectively. In contrast, the growth of P. aeruginosa and S. aureus was not completely inhibited until 1mg/mL AS-ZnO NPs under WL and D. Similarly, AS-ZnO NPs displayed a weaker inhibitory effect against carbapenem-sensitive P. aeruginosa (CSPA) and carbapenem-resistant P. aeruginosa (CRPA) strains of PAC023, PAC041 and PAC032, PAC045 under D. Interestingly, the distinct inhibitory effect was recorded against CSPA PAC041 and CRPA PAC032 in which the bacteria growth was inhibited 99.9% at 250, 500µg/mL under WL. The cytotoxicity results suggested AS-ZnO NPs demonstrated higher toxicity to MCF-7 breast cancer cells than the RAW264.7 macrophage cells. Further, AS-ZnO NPs exhibited higher catalytic potential against tetracycline hydrochloride (TC-H) degradation at 65.6% and 60.8% under WL than the dark at 59.35% and 48.6% within 120min. Therefore, AS-ZnO NPs can be used to design a photo-improved antimicrobial formulation and environmental catalyst for removing TC-H from wastewater.

Amino-Functionalized Pluronic F127 micelles as a dual drug delivery nanostructure for controlled therapeutics release

Bacterial infection is one of the serious leading causes of hospitalization. The development of a novel dual drug delivery nanostructure based on polymeric micelles is presented here for the treatment of Staphylococcus aureus-associated infections. The nanostructure was composed of quercetin (QC)-encapsulated in the core of F127 micelles (FQ micelles) which was later shell cross-linked using 3-amisinopropyl triethoxysilane (APTES) molecules through condensation reaction. The functionalization of the head groups of FQ micelles with APTES (FQA NPs) facilitated the covalent linkage of vancomycin (Vanc) drug and consequent formation of FQA-Vanc NPs with the hydrodynamic size of 133 nm. FQA-Vanc NPs demonstrated prolong release of QC and Vanc over a period of 168 h. The core–shell structure offered sustainable release of Vanc and QC to the FQA-Vanc NPs during 96 h and 48 h, respectively. The co-administration of Vanc and QC not only enhanced the antibacterial performance of FQA-Vanc NPs, but also induced time and concentration-dependent antioxidant activities. Overall, the Vanc immobilized-FQA NPs together with antibacterial and antioxidant activities could potentially provide a new therapeutic platform for bacterial infection treatment.

Deciphering the synergistic potential of mycogenic zinc oxide nanoparticles and bio-slurry formulation on phenology and physiology of Vigna radiata

Abstract Nanobiofertilizers have emerged as an innovative tool for enhancing crop productivity. In the current research, zinc oxide nanoparticles (ZnONPs) were mycosynthesized using cell-free supernatant of Trichoderma harzianum and optimized for physical parameters. Characterization using UV-Visible spectroscopy, dynamic light scattering analysis, zeta potential analysis, X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy-EDX, and HR-Transmission electron microscopy confirmed the formation of ZnONPs with flower-like morphology and average size of 314 nm. The average zeta potential value of the ZnONPs was +1.9 mV indicating the formation of neutral NPs. FTIR peak at 401 cm−1 revealed the presence of ZnONPs. XRD analysis confirmed the hexagonal wurtzite crystalline nature of the ZnONPs. The effect of ZnONPs at 10–1,000 ppm combined with liquid bio-slurry (BS) was studied on seed germination and growth of Vigna radiata. Combination of 250 ppm ZnONPs and BS at 1:2 ratio showed 22.6% increase in shoot length as well as 18.4% increase in root length as compared to control in in vitro studies. In Vivo pot experiments showed no significant difference in secondary metabolites after 60 days, but the root length increased by 38.9% and shoot length increased by 46.95% compared to the control.

Glycerol- and diglycerol-based polyesters: Evaluation of backbone alterations upon nano-formulation performance

Despite the success of polyethylene glycol-based (PEGylated) polyesters in the drug delivery and biomedical fields, concerns have arisen regarding PEG's immunogenicity and limited biodegradability. In addition, inherent limitations, including limited chemical handles as well as highly hydrophobic nature, can restrict their effectiveness in physiological conditions of the polyester counterpart. To address these matters, an increasing amount of research has been focused towards identifying alternatives to PEG. One promising strategy involves the use of bio-derived polyols, such as glycerol. In particular, glycerol is a hydrophilic, non-toxic, untapped waste resource and as other polyols, can be incorporated into polyesters via enzymatic catalysis routes.In the present study, a systematic screening is conducted focusing on the incorporation of 1,6-hexanediol (Hex) (hydrophobic diol) into both poly(glycerol adipate) (PGA) and poly(diglycerol adipate) (PDGA) at different (di)glycerol:hex ratios (30:70; 50:50 and 70:30 mol/mol) and its effect on purification upon NPs formation. By varying the amphiphilicity of the backbone, we demonstrated that minor adjustments influence the NPs formation, NPs stability, drug encapsulation, and degradation of these polymers, despite the high chemical similarity. Moreover, the best performing materials have shown good biocompatibility in both in vitro and in vivo (whole organism) tests. As preliminary result, the sample containing diglycerol and Hex in a 70:30 ratio, named as PDGA-Hex 30%, has shown to be the most promising candidate in this small library analysed. It demonstrated comparable stability to the glycerol-based samples in various media but exhibited superior encapsulation efficiency of a model hydrophobic dye. This in-depth investigation provides new insights into the design and modification of biodegradable (di)glycerol-based polyesters, potentially paving the way for more effective and sustainable PEG-free drug delivery nano-systems in the pharmaceutical and biomedical fields.

Combustion Synthesis of Ag Nanoparticles and Their Performance During NaBH4 Hydrolysis

Due to their tremendous industrial, environmental, and biological applications, research focusing on the synthesis and applications of silver nanoparticles (Ag NPs) has attracted increased interest from researchers over the past two decades. Their structural as well as textural properties can be easily tuned depending on the synthesis protocol utilized. Combustion synthesis has received increased attention as a one-pot route for the synthesis of a wide spectrum of nanomaterials. In this study, we present the results of synthesizing Ag NPs employing urea as a combustion fuel. The effect of the temperature of calcination on the formation and structural features of Ag NPs has been checked over the 400–700 °C temperature range. The characterization of the synthesized Ag NPs has been performed using XRD, SEM, TEM, and XPS techniques. It was found that Ag NPs, with a crystallite size of 40 nm, start to form at around 400 °C. Conducting the calcination at the 500–700 °C range results in the persistence of the obtained Ag NPs. Moreover, the obtained nanomaterials are characterized by a membrane-like morphology. The activity performance of the synthesized Ag NPs was examined for the hydrolysis of sodium borohydride (NaBH4) over a temperature range of 35–50 °C. Increasing the calcination temperature has led to a decrease in the activity of the Ag NPs during the NaBH4 hydrolysis.Graphical

Green synthesis of zinc oxide nanoparticles from Salvadora persica leaf extract: Characterization and studying methyl orange removal by adsorption

Abstract The present study conducted a successful green synthesis of zinc oxide nanoparticles (ZnO NPs) from the aqueous solution of Salvadora persica leaf extract as capping agent and used for methyl orange dye removal. The morphology, chemical composition, crystallinity, optical property and isothermal behavior of synthesized nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Fourier transform infra-red (FTIR), X-ray diffraction (XRD), and UV-visible spectroscopy (UV-Vis). The influencing factors on MO removal such as preparation method, dose, pH, contact time, and dye concentration were examined. The UV-Vis absorption band was found at 365 nm and the XRD analysis confirmed the crystallinity of the ZnO NP and the particle sizes were in the range of 32-68 nm. The FTIR bands confirm the presence of bioactive compounds. SEM images showed the formation of hexagonal and rod-shaped nanoparticles. The results revealed that a maximum methyl orange removal of 68% was obtained with an amount of 0.05 g of ZnO NPs at pH 5. The adsorption process can be well explained by the Langmuir isotherm model. This research demonstrates a green method of preparing various ZnO nanoparticle with a remarkable efficiency towards the removal of methyl orange dye.

Biogenically synthesized palladium nanoparticles for hydrogen evolution study: An efficient catalyst for 4-nitrophenol reduction and C-C coupling reactions

Indian cork extract is employed for the greener production of palladium nanoparticles (Pd NPs) an effective heterogeneous catalyst with a concentration of 30.1%. Plant extract-mediated phytochemicals were found responsible for reducing Pd(II) to Pd(0) without the aid of an external reducing agent. XRD, UV–visible, and other analyses demonstrated the successful formation of Pd NPs. These NPs were evident to have better electrocatalytic activity in the hydrogen evolution reaction (HER) in an acidic medium. The Tafel slope (174 mV/dec) of the Pd NPs catalyst confirmed the Volmer-Heyrovsky mechanism for HER study and demonstrated the electrochemical desorption of hydrogen is the rate-determining step. In terms of synthetic organic chemistry perspectives, the applicability of Pd NPs has been subsequently demonstrated for the reduction of toxic 4-nitrophenol to synthetically important 4-aminophenol with a minimum catalyst loading at ambient conditions. Additionally, the outstanding catalytic activity of synthesized heterogeneous Pd NPs catalyst has been showcased for direct Heck and Hiyama cross-coupling reactions.

Methylene Blue Removal by Copper Oxide Nanoparticles Obtained from Green Synthesis of Melia azedarach: Kinetic and Isotherm Studies

In this study, Melia azedarach fruit extract was used as a reducing agent and copper chloride dihydrate (CuCl2·2H2O) was used as a precursor in the synthesis of copper oxide nanoparticles (CuO NPs). The UV–visible spectrum showed a characteristic absorption peak of CuO NPs at 350 nm. The surface properties of the adsorbent were analyzed through various techniques, indicating the successful formation of CuO NPs. The impacts of several factors, including initial pH (4 to 8), a dose of CuO NPs adsorbent (0.01–0.05 g), dye initial concentration (10–50 mg·L−1), and contact times ranging from 5 to 120 min, were examined in batch adsorption studies. Based on the experimental results, the Langmuir isotherm is well-fitted, indicating MB dye monolayer capping on the CuO NPs surface with 26.738 mg·g−1 as a maximum adsorption capacity Qm value. For the pseudo-second-order kinetic model, the experimental and calculated adsorption capacity values (qe) exhibited good agreement.

Insights into the impact of surfactants on the kinetics of selenium nanoparticles formation via lemon juice-assisted methodology, followed by their antibacterial and antioxidant assessment

Selenium nanoparticles (Se NPs) fabrication utilizing active species of natural lemon juice represents a promising pathway in the biosynthesis of nanoparticles. The reduction of Se4+ to Se(0) could be attributed to the presence of natural lemon juice, which was considered a supplier of vitamin C, polyphenolic compounds, flavonoids, and sugars. The synthesized spherical Se NPs exhibited a characteristic surface plasmon resonance band (SPR) at λ = 320 nm. The values of the rate constant for the reduction of Se (IV) to Se (0) by lemon juice were estimated to be kobs = 0.0011 s−1 for a Se concentration of 0.75 mmol.dm−3 and a lemon content of 0.001 mol.dm−3 at room temperature. Various conditions have been studied on the kinetics of Se NPs formation, such as the doses of SeO2 and lemon juice, and the presence of cationic and/or anionic surfactants like cetyltrimethyl ammonium bromide (CTABr) and sodium dodecyl sulfate (SDS), respectively. The synthesized Se particles were characterized by physicochemical techniques such as FT-IR, XRD, TEM, DLS, and zeta potential to investigate their main functional groups, crystallinity, chemical composition, particle size, and surface morphology. Moreover, the antioxidant power of Se NPs was tested in terms of their DPPH free radical scavenging activity. Finally, the antibacterial activity of the studied nanoparticles was confirmed against gram-positive and gram-negative bacteria (Staphylococcus aureus and Pseudomonas aeruginosa, respectively). In short, this study introduced the impact of surfactants on the formation of biocompatible Se NPs as an active antibacterial and antioxidant.

Facile synthesis of MnO2 nanoparticles for the removal of cationic dye

Abstract MnO2 NPs were synthesized from Delonix elata leaves extract act as a capping and reducing agent by green synthesis process. The synthesized MnO2 NPs were characterized by different spectroscopic techniques such as IR, UV-Vis, SEM and XRD analyses. The UV spectrum of synthesized MnO2 NPs revealed optical properties at 340 nm. The XRD pattern of MnO2 NPs exhibited the crystallite size to be in the range of 20 nm and shows the amorphous structure. The morphological geographies of MnO2 NPs are spherical and faintly agglomerated. The FT-IR spectrum of MnO2 NPs spectacles stretching vibration of Mn–O at 510 cm−1 confirmed the formation of MnO2 NPs. MnO2 is superior photo degradation for methylene blue which is extant in the textile industries and it has an unlimited potential application in wastewater treatment.

Green formation of Ag NPs in ultrasonic condition and treatment of lupus nephritis by following the TGF-β1 signaling pathway in mice

This study demonstrated the biosynthesis of silver nanoparticles using Allium jesdianum leaves extract under mild procedure as a reducer-stabilizer agent in the presence of ultrasonic irradiation. Various techniques like UV–Vis, FE-SEM, EDS-elemental mapping, FT-IR, TEM, XRD and ICP-OES were applied to characterize the obtained nanoparticles. The TEM results shown that the produced Ag NPs were well-dispersed as spherical shaped with average sizes ranging from 20 to 30 nm. UV–Vis data for Ag NPs were appearing in 465 nm. Novelty of the surface engineered nanocomposite was demonstrated by assaying its catalytic performance in the reduction of 4-nitrophenol (4-NP) as a toxic water pollutant organic dye by NaBH4 under mild condition. The prepared catalyst was successfully reused up to 8 times in the reactions without significant loss in activity. In animal experiment, a lupus nephritis mouse model was established by pristane to confirm the Ag NPs/A. jesdianum nanocomposite interventional efficacy by regulating the signaling pathway of TGF-β1. The histopathological slides were taken from the kidney for investigating the sign of lupus nephritis. The concentrations of IFN-γ, TNF-α, IL-12, and IL-6 were analyzed in kidney and serum by ELISA kits. The VEGF, TGF-β1, and Mn-SOD mRNA expression was assessed in the kidney to prove the treatment of lupus nephritis by Ag NPs/A. jesdianum nanocomposite by following the TGF-β1 signaling pathway in mice. Ag NPs/A. jesdianum nanocomposite reduced the urinary protein, TNF-α, IFN-γ, IL-12 and IL-6 elevation in kidney and serum. In addition, Ag NPs/A. jesdianum nanocomposite decreased the ALB, TP, TG, BUN, TC, and SCr in mice with nephritis. Ag NPs/A. jesdianum nanocomposite prevented the dsDNA antibodies positive rate. Ag NPs/A. jesdianum nanocomposite downregulated the VEGF and TGF-β1 mRNA expression in the lupus nephritis mice kidneys.

Combinational antimicrobial activity of biogenic TiO2 NP/ZnO NPs nanoantibiotics and amoxicillin-clavulanic acid against MDR-pathogens

The development of effective strategies against multidrug-resistant (MDR) pathogens is an urgent need in modern medicine. Nanoantibiotics (nABs) offer a new hope in countering the surge of MDR-pathogens. The aim of the current study was to evaluate the antibacterial activity of two attractive nABs, TiO2 NPs and ZnO NPs, and their performance in improving the antimicrobial activity of defined antibiotics (amoxicillin-clavulanic acid, amox-clav) against MDR-pathogens. The nABs were synthesized using a green method. The physicochemical characteristics of the synthesized nanoparticles were determined using standard methods. The results showed the formation of pure anatase TiO2 NPs and hexagonal ZnO NPs with an average particle size of 38.65 nm and 57.87 nm, respectively. The values of zeta potential indicated the high stability of the samples. At 8 mg/mL, both nABs exhibited 100 % antioxidant activity, while ZnO showed significantly higher activity at lower concentrations. The antibiofilm assay showed that both nABs could inhibit the formation of biofilms of Acinetobacter baumannii 80 and Escherichia coli 27G (MDR-isolates). However, ZnO NPs showed superior antibiofilm activity (100 %) against E. coli 27G. The MIC values were determined to be 8 (1), 2 (2), and 4 (4) mg/mL for amox-clav, TiO2 NPs, and ZnO NPs against A. baumannii 80 (E. coli 27G), respectively. The results showed that both nABs had synergistically enhanced antibacterial performance in combination with amox-clav. Specifically, an 8-fold reduction in MIC values of antibiotics was observed when they were combined with nABs. These findings highlight the potential of TiO2 NPs and ZnO NPs as effective nanoantibiotics against MDR-pathogens. The synergistic effect observed when combining nABs with antibiotics suggests a promising approach for combating antibiotic resistance. Further research and development in this area could lead to the development of more effective treatment strategies against MDR infections.

Exploring the synergistic effect of palladium nanoparticles and highly dispersed transition metals on carbon nitride/super-activated carbon composites for boosting electrocatalytic activity

In the present work, multifunctional electrocatalysts formed by palladium nanoparticles (Pd NPs) loaded on Fe or Cu-containing composite supports, based on carbon nitride (C3N4) and super-activated carbon with a high porosity development (SBET 3180 m2/g, VDR 1.57 cm3/g, and VT 1.65 cm3/g), were synthesised. The presence of Fe or Cu sites favoured the formation of Pd NPs with small average particle size and a very narrow size distribution, which agreed with Density Functional Theory (DFT) calculations showing that the interaction of Pd clusters with C3N4 flakes is weaker than with Cu- or Fe-C3N4 sites. The electroactivity was also dependent on the composition and, as suggested by preliminary DFT calculations, the Pd-Cu catalyst showed lower overpotential for hydrogen evolution reaction (HER) while bifunctional oxygen reduction reaction/ oxygen evolution reaction (ORR/OER) behaviour was superior in Pd-Fe sample. The Pd-Fe electrocatalyst was studied in a zinc-air battery (ZAB) for 10 h, showing a performance similar to a commercial Pt/C + RuO2 catalyst with a high content of precious metal. This study demonstrates the synergistic effect between Pd species and transition metals and shows that transition metals anchored on C3N4-based composite materials promote the electroactivity of Pd NPs in HER, ORR and OER due to the interaction between both species.

Synthesis and characterization of titanium dioxide nanoparticles from Bacillus subtilis MTCC 8322 and its application for the removal of methylene blue and orange G dyes under UV light and visible light.

Over the last decade there has been a huge increase in the green synthesis of nanoparticles. Moreover, there is a continuous increase in harnessing the potential of microorganisms for the development of efficient and biocompatible nanoparticles around the globe. In the present research work, investigators have synthesized TiO2 NPs by harnessing the potential of Bacillus subtilis MTCC 8322 (Gram-positive) bacteria. The formation and confirmation of the TiO2 NPs synthesized by bacteria were carried out by using UV-Vis spectroscopy, Fourier transforms infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX/EDS). The size of the synthesized TiO2 NPs was 80-120nm which was spherical to irregular in shape as revealed by SEM. FTIR showed the characteristic bands of Ti-O in the range of 400-550cm-1 and 924cm-1 while the band at 2930cm-1 confirmed the association of bacterial biomolecules with the synthesized TiO2 NPs. XRD showed two major peaks; 27.5° (rutile phase) and 45.6° (anatase phase) for the synthesized TiO2 NPs. Finally, the potential of the synthesized TiO2 NPs was assessed as an antibacterial agent and photocatalyst. The remediation of Methylene blue (MB) and Orange G (OG) dyes was carried out under UV- light and visible light for a contact time of 150-240min respectively. The removal efficiency for 100ppmMB dye was 25.75% and for OG dye was 72.24% under UV light, while in visible light, the maximum removal percentage for MB and OG dye was 98.85% and 80.43% respectively at 90min. Moreover, a kinetic study and adsorption isotherm study were carried out for the removal of both dyes, where the pseudo-first-order for MB dye is 263.269 and 475554.176mg/g for OG dye. The pseudo-second-order kinetics for MB and OG dye were 188.679 and 1666.667mg/g respectively. In addition to this, the antibacterial activity of TiO2 NPs was assessed against Bacillus subtilis MTCC 8322 (Gram-positive) and Escherichia coli MTCC 8933 (Gram-negative) where the maximum zone of inhibition in Bacillus subtilis MTCC 8322 was about 12mm, and for E. coli 16mm.

Control of Self-Assembly and Elemental Mixing of AuNi Bimetallic Nanoparticles via Solid-State and Liquid-State Dewetting of Metal Thin Films

Immiscible Au-Ni alloy thin films undergo phase separation and dewetting because of thermodynamic and morphological instability at elevated temperatures below the miscibility gap. We report the formation and assembly of bimetallic nanoparticles (BNPs) on topographic Si templates. An ordered array of inverted pyramidal pits were produced via solid-state and liquid-state dewetting of a 12-nm-thick Au-Ni thin film by respectively using thermal annealing and laser irradiation. Upon direct thermal annealing at 600 and 800 <sup>o</sup>C, the thin film on the templates self-assembled into an ordered array of BNPs composed of Au-rich and Ni-rich sub-clusters in pits. But the relative proportions of the two sub-clusters varied with annealing temperature due to the additional formation of smaller Ni-rich NPs that were scattered around the BNPs. Laser irradiation of the film, in contrast, formed an ordered array of fully mixed alloy NPs on the template and left no other residues on the surface. Subsequent thermal annealing induced the elements within the NPs to segregate, resulting in Au-rich and Ni-rich sub-clusters. In brief, the combination of solid-state and liquidstate dewetting processes on a topographic template not only enabled the 2-dimesional self-assembly of BNPs but also allowed control of the mixing of alloying elements within the BNPs. These results offer insights into the tailored fabrication of BNPs, which have potential applications in bio-functional catalysts, and plasmonic and chemical sensors.

Fabrication of Ni and Mn co-doped ZnFe2O4 spinel ferrites and their nanocomposites with rGO as an efficient photocatalyst for the remediation of organic dyes

Herein, we have synthesized Ni and Mn co-doped ZnFe2O4 ferrites using the simple co-precipitation method and their nanocomposites (NCs) with 10 % rGO using the ultra-sonication route. The structural investigation revealed the successful formation of single-phase ZnFe2O4 NPs with cubic spinel ferrite geometry. The crystallite size was determined to be in the range of 21 nm to 28 nm. The current–voltage (I-V) analysis revealed that Ni and Mn co-doping and the addition of rGO nanosheets in ZnFe2O4 NPs boosted the electrical responses of the fabricated Zn1-xNixFe2-yMnyO4/rGO NCs. The BET analysis indicates an increase in the surface area of Zn1-xNixFe2-yMnyO4/rGO NCs (132 m2/g) that might be attributed to the inclusion of rGO nanosheets, which prevents the NPs from agglomeration. The photocatalytic evaluation of the pristine ZnFe2O4 NPs, Ni and Mn co-doped Zn1-xNixFe2-yMnyO4 NPs, and Zn1-xNixFe2-yMnyO4/rGO NCs photocatalysts was tested by photodegradation of malachite green (MG) dye under sunlight irradiation. Results exhibited improved photocatalytic responses and degraded 94.6 % of MG dye in 45 min using Zn1-xNixFe2-yMnyO4/rGO NCs, which was much higher compared to the Ni and Mn co-doped Zn1-xNixFe2-yMnyO4 NPs (58.7 %) and pristine ZnFe2O4 NPs (38.3 %). The increased degradation potential of Zn1-xNixFe2-yMnyO4/rGO NCs was accredited to the highly conducting nature and 2D nano-sheets of rGO, which efficiently inhibited the recombination of charge carrier species. Ultimately, the remarkable photocatalytic capability exhibited by Zn1-xNixFe2-yMnyO4/rGO NCs implies that the synthesized NCs could have auspicious practical applications in the elimination of dyes from wastewater.