G. Nagaraju

Green synthesis of CuO nanoparticles using Gloriosa superba L. extract and their antibacterial activity

Abstract The investigation aims at the synthesis of copper oxide nanoparticles (CuO Nps) using Gloriosa superba L. plant extract as fuel by solution combustion synthesis, their characterization and studies on antibacterial activities against selected pathogenic bacteria. X-ray diffraction studies showed that the particles are monoclinic in nature. The UV–visible absorption spectrum of CuO Nps indicates the blue shift with increase of concentration of plant extract. SEM images reveal that the particles are spherical in nature. TEM image indicates that as-formed CuO Nps are spherical in shape, and the size is found to be in the range 5–10 nm. Further, as-formed CuO Nps exhibit significant antibacterial activity against pathogenic bacterial strains namely Gram −ve Klebsiella aerogenes, Pseudomonas desmolyticum, and Escherichia coli, Gram +ve bacteria Staphylococcus aureus. The current study demonstrates convenient utilization of Gloriosa superba L. extract as a fuel for the efficient synthesis of CuO nanoparticles through a green synthesis method to obtain significantly active antibacterial material.

Synthesis and Characterization of CeO2 Nanoparticles via Solution Combustion Method for Photocatalytic and Antibacterial Activity Studies.

CeO2 nanoparticles have been proven to be competent photocatalysts for environmental applications because of their strong redox ability, nontoxicity, long-term stability, and low cost. We have synthesized CeO2 nanoparticles via solution combustion method using ceric ammonium nitrate as an oxidizer and ethylenediaminetetraacetic acid (EDTA) as fuel at 450 °C. These nanoparticles exhibit good photocatalytic degradation and antibacterial activity. The obtained product was characterized by various techniques. X-ray diffraction data confirms a cerianite structure: a cubic phase CeO2 having crystallite size of 35 nm. The infrared spectrum shows a strong band below 700 cm−1 due to the Ce−O−Ce stretching vibrations. The UV/Vis spectrum shows maximum absorption at 302 nm. The photoluminescence spectrum shows characteristic peaks of CeO2 nanoparticles. Scanning electron microscopy (SEM) images clearly show the presence of a porous network with a lot of voids. From transmission electron microscopy (TEM) images, it is clear that the particles are almost spherical, and the average size of the nanoparticles is found to be 42 nm. CeO2 nanoparticles exhibit photocatalytic activity against trypan blue at pH 10 in UV light, and the reaction follows pseudo first-order kinetics. Finally, CeO2 nanoparticles also reduce CrVI to CrIII and show antibacterial activity against Pseudomonas aeruginosa.

Electrochemical Sensing of Dopamine and Antibacterial Properties of ZnO Nanoparticles Synthesized from Solution Combustion Method

We have successfully synthesized ZnO nanoparticles (NPs) from solution combustion method using combustible fuel (Green gram). XRD pattern confirms that the prepared compound is composed of wurtzite hexagonal zinc-oxide. FTIR spectrum of ZnO NPs shows the band at ~ 417 cm-1 associated with the characteristic vibration of Zn-O. The UV-Vis spectrum shows a strong absorption band at ~ 365 nm which is blue shifted due to quantum confinement effect. TEM images show the average sizes of the nanoparticles are found to be almost ~ 15–30 nm. The as-synthesized product shows good electrochemical sensing of dopamine. Furthermore the antibacterial properties of ZnO NPs were investigated by their bactericidal activity against four bacterial strains using the agar well diffusion method.

Citrus maxima (Pomelo) juice mediated eco-friendly synthesis of ZnO nanoparticles: Applications to photocatalytic, electrochemical sensor and antibacterial activities ☆

In the present work, Zinc oxide nanoparticles (ZnO Nps) have been successfully prepared through a simple, effective and low cost solution combustion method using Zn (NO3)2·6H2O as an oxidizer, chakkota (Common name=Pomelo) fruit juice as novel fuel. X-ray diffraction pattern indicates the hexagonal wurtzite structure with average crystallite size of ~22nm. ZnO Nps were characterized with the aid of different spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Photoluminescence and UV-Visible spectroscopy. FTIR shows characteristic ZnO vibrational mode at 393cm-1. SEM images show that the particles are agglomerated. TEM image shows the size of the particles are about 10-20nm. Further, in order to establish practical applicability of the synthesized ZnO Nps, photocatalytic degradation of methylene blue (MB) dye as a model system was studied in presence of UV (665nm) light. In addition to this, the antibacterial activity was screen against 3 bacterial strains and electrochemical sensor performance towards the quantification of dopamine at nano molar concentrations was also explored.

Electrochemical Sensing, Photocatalytic and Biological Activities of ZnO Nanoparticles: Synthesis via Green Chemistry Route

In this paper, we have successfully synthesized ZnO nanoparticles (Nps) via solution combustion method using sugarcane juice as the novel fuel. The structure and morphology of the synthesized ZnO Nps have been analyzed using various analytical tools. The synthesized ZnO Nps exhibit excellent photocatalytic activity for the degradation of methylene blue dye, indicating that the ZnO Nps are potential photocatalytic semiconductor materials. The synthesized ZnO Nps also show good electrochemical sensing of dopamine. ZnO Nps exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Eschesichia coli and Staphylococcus aureus using agar well diffusion method. Furthermore, the ZnO Nps show good antioxidant activity by potentially scavenging 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The above studies clearly demonstrate versatile applications of ZnO synthesized by simple eco-friendly route.

Ionic liquid-assisted hydrothermal synthesis of TiO2 nanoparticles and its applications towards the photocatalytic activity and electrochemical sensor

This work reports the synthesis of TiO2 nanoparticles via ionic liquid-assisted hydrothermal method at 130 °C for two days. The obtained product was characterised by various techniques. The X-ray diffraction data reveal the anatase phase TiO2 nanoparticles with crystallite size 37 nm. The Fourier transform infrared spectrum shows a band at 400 cm−1 due to Ti–O–Ti stretching vibration, in addition to the presence of ionic liquid. The UV–Vis spectrum of TiO2 nanoparticles shows an absorption band at 314 nm which indicates a blueshift compared with that of bulk TiO2. The transmission electron microscopy images show almost spherical-shaped nanoparticles with an average diameter of 40–80 nm. TiO2 nanoparticles exhibit excellent photocatalytic activity for the degradation of trypan blue, and also help in the reduction of Cr+6 to Cr+3. TiO2 nanoparticles modified glassy carbon electrode exhibits better electrocatalytic oxidation towards dopamine compared with bare glassy carbon electrode.

One pot green synthesis of MnCO3–rGO composite hybrid superstructure: application to lithium ion battery and biosensor

Herein, hierarchical superstructures of MnCO3 and MnCO3–rGO hybrid nanocomposites with controlled morphologies, such as cube, spherical, dumbbell, and oval, were synthesized via an environmentally friendly hydrothermal treatment using green tea extract (GTE) as a reducing agent as well as a shape controlling agent. During the hydrothermal treatment, the GTE produces carbonate species in the presence of a strong oxidising agent, such as KMnO4, and reduces graphene oxide to graphene. Different superstructures of MnCO3 and MnCO3–rGO were obtained by controlling the reaction time. A tentative growth mechanism for the generation of MnCO3 superstructures is proposed based on the morphologies obtained at different intervals of time. Additionally, MnCO3 and MnCO3–rGO have been used as anode materials for Li-ion batteries. Galvanostatic charge–discharge study shows intercalation/de-intercalation of lithium, which is a characteristic of a battery material. Based on this, it can be concluded that the as-synthesized MnCO3 and MnCO3–rGO with controlled morphologies are important electrode materials for Li-ion batteries. At a current rate of 0.06C, the MnCO3–rGO electrode produces a specific discharge capacity of 340 mA h g−1 after 50 cycles of charge–discharge. MnCO3–rGO is also examined for dopamine (DA) detection using amperometric techniques. Linear current responses were obtained for the DA concentration in the range between 0.2 and 300 μM with 0.999 as the correlation coefficient. The limit of detection (LOD) for DA is found to be 20 nM. The response is not hindered by the presence of other bioanalytes and is reproducible, and the prepared electrodes are stable over a month when stored in a vacuum dessicator.

Heterojunction CuO-TiO2 nanocomposite synthesis for significant photocatalytic hydrogen production

Effective and low-cost photocatalysts have been synthesized by a simple hydrothermal process. In this process, the two CuO and TiO2 bound one over the other and formed a heterojunction CuO-TiO2 nanocomposite. CuO serves as electron reservoir by receiving electrons from TiO2, which suppresses the recombination of e−/h+ and transfers the received electron to split water, which results in enhanced H2 production. Heterojunction CuO-TiO2 nanocomposite material recorded a maximum of 9284 μmolg−1 H2 production for 2.5 h. The recorded result is 15 times higher than bare TiO2 and 16 times higher than bare CuO. The synthesized materials were characterized and analyzed using various analytical techniques such as XRD, FTIR, UV–vis spectra and the morphology was studied using SEM, TEM, and HRTEM images.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm−1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

Antibacterial and Photocatalytic Activities of ZnO Nanoparticles: Synthesized Using Water Melon Juice as Fuel

In the present work, Zinc Oxide nanoparticles (ZnO Nps) have been prepared by a simple and low temperature solution combustion method using Zinc nitrate as a precursor and solid water melon juice as a novel fuel for the first time. The structure and morphology of the synthesized ZnO NPs have been analyzed using various analytical techniques such as Powder X-ray diffraction, FTIR spectroscopy, Raman spectroscopy, UV-Visible spectroscopy, photoluminescence spectroscopy, scanning electron microscope and transmission electron microscope. ZnO NPs show good photo catalytic activity for the degradation of methylene blue (MB) dye. It also shows significant antibacterial activities against three bacterial strains.