Herein, we report a sustainable production of magnetic cobalt ferrite nanoparticles by conventional (CHM) and microwave heating (MHM) method. Hibiscus rosa-sinensis extract was used as both reducing and stabilizing agent. Using plant extracts to synthesize nanoparticles has been considered as an eco-friendly method, since it avoids noxious chemicals. The plethora of plant extract mediated nanoparticles were compared by techniques, such as XRD, Rietveld, FT-IR, SEM, EDX, UV-Visible DRS, PL and VSM were carried out to analyze and understand their crystallite size, functional groups, morphology, optical and magnetic properties. The crystalline structure of cobalt ferrite nanoparticles revealed the cubic structure and the microwave heating of nanoparticles showed smaller crystallite size compared to the conventional heating, which was then confirmed by XRD analysis. To analyze the presence of functional groups and the phytochemical involvement of the plant extract was confirmed by FT-IR studies. Spherical morphology with less than 100 nm sized particles was confirmed by SEM and EDX analysis confirm the existence of Co, O, and Fe elements present in the samples. UV-Visible DRS studies were carried out to calculate the band gap of the as-synthesized nanoparticles, estimated from the Kubelka-Munk function, as 2.06, and 1.87 eV for CHM and MHM, respectively. Photoluminescence emission spectrum of the nanoparticles showed two different bands at 494 and 620 nm, which explores the optical properties of the nanoparticles, due to the quantum confinement effect. VSM analysis showed better ferromagnetic behavior, which can be used for magnetic applications. © 2017 Elsevier Ltd and Techna Group S.r.l.

John Kennedy L

Physics

School of Advanced Sciences

Chennai Campus

Kombaiah K

Vijaya J.J

Bououdina M

Ramalingam R.J

Al-Lohedan H.A.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Ceramics International

A simple and rapid synthesis has been developed to synthesize NiFe2O4 nanoparticles with tunable optical, magnetic and catalytic properties by using Hibiscus rosa sinensis plant extract in the current study. The crystalline structure of the synthesized NiFe2O4 nanoparticles was confirmed by X-Ray diffraction (XRD) and Rietveld refinement analysis. Morphological, elemental, magnetic and optical properties of the synthesized nanoparticles were interpreted by fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), UV–Visible diffused reflectance spectroscopy (UV-DRS), photoluminescence (PL) studies, and vibrating sample magnetometer (VSM). XRD analysis showed the single phase crystalline nature with average crystallite size of 50–70 nm. SEM and EDX analysis recognize the spherical shape nanoparticles and phase purity of the samples. The optical band gap is determined using UV-DRS spectra and is observed to decrease with increasing the calcination temperature. VSM studies obviously demonstrate the ferromagnetic property of the samples. The value of saturation magnetization has decreased with an increase in the calcination temperature and the coercivity is decreased. Additionally, NiFe2O4 nanoparticles were investigated for the catalytic reduction capability for different dyes like Rhodamine-B (Rh-B), Methylene blue (MB), Rose Bengal (RB), and Congo red (CR). It is found that the dye solution was degraded with increasing irradiation time. Hence, the prepared nanoparticles have been used as high potential catalysts for the reduction of organic dyes in the application of waste water treatment. NiFe2O4 is an active agent in catalyzing the oxidation of glycerol to formic acid with good conversion percentage and high selectivity. This catalytic system in the polar solvents, such as, acetonitrile provides the enhanced conversion results. The very important role played by a variety of reaction parameters in deciding the catalytic effectiveness is well established and every parameter has an optimal value to acquire the maximum catalytic activity. © 2018 Elsevier B.V.

Materials Chemistry and Physics

Catalytic studies of NiFe2O4 nanoparticles prepared by conventional and microwave combustion method

Nanosized copper ferrite (CuFe2O4) nanoparticles have been prepared by conventional (CCM) and microwave (MCM) combustion methods using Hibiscus rosa sinensis plant extract as a fuel. XRD and rietveld analysis confirmed the formation of single cubic phase and with crystallite size varying from 25 to 62 nm owing to grain growth after calcination. FT-IR analysis confirms the modes of the cubic CuFe2O4 phase, due to the stretching and bending vibrations. Spherical shaped particles are observed by scanning electron microscopy and the average particle size is found to be in the range of 50–200 nm. The chemical composition is confirmed by energy dispersive X-ray analysis. The optical band gap energy estimated using Kubelka-Munk function with the help of UV–Visible diffused reflectance spectroscopy, is found to be 2.34 and 2.22 eV for CCM and MCM respectively. Photoluminescence analysis indicates that both samples absorb light in the UV–visible region and exhibit emissions at 360, 376, and 412 nm. Magnetic measurements indicate a ferromagnetic behavior, where both magnetic properties very much influenced by the preparation method and calcination temperature: both saturation magnetization and coercivity are found higher when using CCM and MCM; from 29.40 to 34.09 emu/g while almost double from 224.4 to 432.2 Oe. The observed changes in physical properties are mainly associated with crystallinity, particle size, better chemical homogeneity, and cations distribution among tetrahedral/octahedral sites. The maximum specific absorption rate obtained was 14.63 W/g, which can be considered suitable and favorable for magnetic hyperthermia. This study highlighted the benefits of green synthesis of CuFe2O4 nanoparticles providing better magnetic properties for the platform of hyperthermia application. © 2017 Elsevier Ltd

Journal of Physics and Chemistry of Solids

Conventional and microwave combustion synthesis of optomagnetic CuFe2O4 nanoparticles for hyperthermia studies

Simple, cost effective and low temperature synthesis of pure and Cd2+ doped zinc ferrite nanoparticles have been successfully synthesized by a microwave assisted combustion method using metal nitrates as oxidizing agent and L-arginine as a reducing agent. The stoichiometric ratio of precursors taken was 1:2. X-ray diffraction, Rietveld, FTIR, HRSEM, DRS, PL, and VSM techniques are carried out to characterize the samples for the structural phases, functional groups, morphology, optical and magnetic properties. Upon the combustion method, the crystallinity and size variation of the nanoparticles were decreased from 42 nm to 12 nm with increasing the concentration of the dopant. The lattice parameter of the spinel structure increases when the size of the nanoparticles reduced. FTIR spectra confirmed the presence of metal oxides absorption bands at lower and higher frequency regimes, due to tetrahedral, and octahedral stretching vibrations respectively. HRSEM images showed the presence of spherical particles in the nano-regime. The bandgap energy of the samples was estimated by diffuse reflectance spectra and it decreased with increasing dopant concentration which was calculated from Tauc's relation. Photoluminescence (PL) spectroscopy used to investigate the emission of the samples with the excitation wavelength at 414 nm and emission at 486 nm. Vibrating sample magnetometer under applied magnetic field was used to carry out the magnetic measurements and it revealed at decrease in saturation magnetization and an increase in coercivity with an increase in the concentration of Cd2+ ions. The microwave combustion method produces the ferrite nanoparticles as clean, non-toxic, environment-friendly with high yield of product in a shorter reaction time. The future plan of this research is to synthesize highly active catalyst for the photocatalytic mineralization of industrial effluent in large scale. © 2017 Elsevier GmbH

Optik

Effect of Cd2+ concentration on ZnFe2O4 nanoparticles on the structural, optical and magnetic properties

Nanocrystalline ZnFe2O4 samples were synthesized by both conventional combustion method (CCM) and microwave assisted combustion method (MCM) using Hibiscus rosa-sinensis plant extract for comparison purpose. The prepared ZnFe2O4 samples were characterized by X-ray diffraction (XRD), Rietveld analysis, Fourier transform-infrared spectrophotometer (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and vibrating sample magnetometer (VSM). The formation of single phase ZnFe2O4 was confirmed by XRD and FT-IR. The lattice parameter was calculated by Rietveld analysis. The change in the particle size ranges from 372.0 to 541.7 nm and 23.4 to 48.5 nm respectively for the conventional and microwave methods and has been clearly shown by HRSEM. UV-visible diffuse reflectance spectroscopy is used to measure the band gaps of ZnFe2O4, which is about 2.1 eV. Single phase ZnFe2O4 emits the photoluminescence bands at 486, 530, 542, and 566 nm. The magnetic properties of the synthesized ZnFe2O4 nanoparticles were investigated by VSM studies and the hysteresis loops were studied at room temperature. The saturation magnetization (Ms) of ZnFe2O4-CCM (63.61 emu/g) is lesser than that of ZnFe2O4-MCM (255.7 emu/g). ZnFe2O4 nanoparticles prepared by the microwave assisted combustion method were found to have higher surface area and lower crystallite size than ZnFe2O4 nanoparticles prepared by the conventional combustion method. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Studies on the microwave assisted and conventional combustion synthesis of Hibiscus rosa-sinensis plant extract based ZnFe2O4 nanoparticles and their optical and magnetic properties

Scientific Reports

Photodegradation of organic pollutants RhB dye using UV simulated sunlight on ceria based TiO2 nanomaterials for antibacterial applications

Synthesis of nanocrystalline cobalt ferrite through soft chemistry methods: A green chemistry approach using sesame seed extract

Materials Science and Engineering: B

Solution processing of CuSe quantum dots: Photocatalytic activity under RhB for UV and visible-light solar irradiation

Comparative investigation on the structural, morphological, optical, and magnetic properties of CoFe2O4 nanoparticles

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ISSN	0272-8842
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