scholarly journals Facile Synthesis, Characterization, Catalytic and Photocatalytic Activity of Multiferroic BiFeO3 Perovskite Nanoparticles

M Sukumar ◽  
M. Mathankumar ◽  
Chandra Sekhar Dash ◽  
M. Sundararajan ◽  
Mohd Ubaidullah ◽  

Abstract We report the synthesis of multiferroic BiFeO3 perovskite nanoparticles using the microwave combustion technique. Phase evolution is investigated by X-ray diffraction (XRD), which confirms that the formation of a secondary α-Bi2O3 phase with a monoclinic structure along with the existing rhombohedral (BiFeO3) structure. The average crystalline size has been found at 50 nm. The optical band gap was calculated from the Tauc’s plot it has been found 2.18 eV, as measured by diffuse reflectance spectroscopy (DRS). The appearances of Fourier transform infrared spectroscopy (FT-IR) absorption bands at 550 and 444 cm-1 were correlated to the rhombohedral stretching modes of bismuth ferrite nanostructure. The morphology observations using scanning electron microscopy (SEM) showed the formation of nanosized grains with pores. Energy-dispersive X-ray analysis (EDX) was done to confirm the extent of Bi3+, Fe3+, and O2- in the samples. The magnetization-Field (M-H) hysteresis curves recorded from the vibrating sample magnetometer (VSM) revealed the appearance of ferrimagnetic behavior at room temperature. The specific surface area characterized by N2 adsorption-desorption isotherm is found 44.86 m2 g-1 using Brunauer-Emmett-Teller (BET) technique. The as-fabricated BiFeO3 perovskite nanoparticles were investigated for their superior catalytic activity in two applications, which include (i) the conversion of glycerol to formic acid in a selective liquid phase batch reactor at atmospheric pressure. This bismuth-based nanoparticles exhibit as an efficient multifunctional catalyst with high conversion and selectivity efficiency around 99.2% and 98.5%, respectively, (ii) the photocatalytic degradation of rhodamine B under visible light irradiation is found maximum efficiency (99.9%), when a small amount of H2O2 was added during photocatalysis, indicating the samples possessed photo-Fenton like catalytic activity. Finally, we concluded that the BiFeO3 perovskite nanoparticles' high performance in future multifunctional devices is demonstrated by the simultaneous enhancement of catalytic and photocatalytic activities.

2012 ◽  
Vol 11 (05) ◽  
pp. 1250030 ◽  

The advantage of doping of TiO2 with copper has been utilized for enhanced degradation of pesticide under visible light irradiation. The sol–gel method has been undertaken for the synthesis of copper-doped TiO2 by varying the dopant loadings from 0.25 wt.% to 1.0 wt.% of Cu2+ . The doped samples were characterized by UV-Visible Diffuse Reflectance Spectroscopy (DRS), N2 adsorption–desorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectrometry (EDS). The photocatalytic activity of the catalyst was tested by degradation of dichlorvos under visible light illumination. The results found that 0.75 wt.% of Cu2+ doped nanocatalysts have better photo catalytic activity than the rest of percentages doped, undoped TiO2 and Degussa P25. The reduction of band gap was estimated and the influence of the process parameters on photo catalytic activity of the catalyst has been explained.

2021 ◽  
Vol 11 (1) ◽  
pp. xx-xx
Nga Phan To ◽  
Lien Nguyen Hong ◽  
Tuyen Le Van ◽  
Nhan Phan Chi ◽  
Huyen Phan Thanh

Porous LaFeO3 were synthesised by nanocasting method using mesoporous silica (SBA-15) as a hard template and used as a visible-light-driven photocatalyst. The as-synthesised LaFeO3 photocatalyst were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD), N2 adsorption-desorption, and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-vis DRS). The photo-Fenton catalytic activities of porous LaFeO3 were investigated for the degradation of oily-containing wastewater. The results showed that porous LaFeO3 had better photo-Fenton catalytic activity under visilbe light irradiation than pure LaFeO3. The remarkable improvement photo-Fenton catalytic activity of porous LaFeO3 material could be attributed to the synergistic effect of adsorption and visible light photo-Fenton processes thanks to its porous structure.

Clay Minerals ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 53-61 ◽  
H. C. B. Hansen ◽  
C. Bender Koch

AbstractStichtite is the layered Mg-Cr(III) hydroxide carbonate of the pyroaurite group. The possibility of describing Cr(III) short range order (SRO) in stichtite by use of ion chromatography of the Cr(III)-hydroxo species following acid dissolution of the compound is described. Two synthetic stichtites of similar composition (average Mg5.73Cr(III)2.27(OH)15.93(O)0.07(CO3)1.10·xH2O) prepared in the absence or presence of hydroxy-bridged Cr(III) dimers and a sample from Dundas, Tasmania, Mg6.29Ni(II)0.02Cr(III)0.90Al0.65Fe(III)0.15(OH)15.26(OH2)0.74(CO3)1.23·xH2O have been examined. Ion chromatography showed the highest degree of SRO for the Dundas stichtite. For the synthetic stichtites the sample synthesized from Cr(III) dimers had the highest SRO. No information on cation ordering could be extracted from powder X-ray diffraction data. Visible spectroscopy indicates that for constant Mg:Cr(III) ratio the crystal field splitting increases with increasing SRO. Two different OH-stretching IR absorption bands (3585 and 3472 cm−1) are assigned to OH coordinated to 3Mg and OH coordinated to 2MgCr or Mg2Cr, respectively.

2021 ◽  
Vol 11 (1) ◽  
pp. xx-xx
Anh Dang Thi Thu ◽  
Dat Nguyen Tien ◽  
Tuan Doan Anh ◽  
Huyen Vuong Thanh ◽  
Huyen Pham Thanh

The SAPO-56 molecular sieve material was prepared under hydrothermal conditions at 200 °C with different hydrothermal times using precursors including Al(OH)3, LUDOX AS-30, H3PO4, and TMHD (N,N,N′,N′-tetramethyl-hexane-1,6-diamine) as an organic structure-directing agent. The samples were characterized by X-ray diffraction, field emission scanning electron microscopes, Energy-dispersive X-ray spectroscopy, NH3 temperature - programmed desorption, N2 adsorption-desorption, and UV-Vis Diffuse Reflectance Spectroscopy methods. Electron paramagnetic resonance technique was applied to determine isolated Cu2+ ions in the framework. Although materials shared the same AFX framework structure, they owned different physicochemical properties, especially in terms of crystal size, surface area, and acidity. Next, the catalytic activity of removal NOx of Cu/SAPO-56 and Cu/ZSM-5 using commercial ZSM-5 as support with the loading of 3 wt%Cu synthesized by aqueous ion-exchange method was assessed in the selective catalytic reduction with NH3.

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 781
Xinli Yang ◽  
Nan Wu ◽  
Yongxia Miao ◽  
Haobo Li

Tungsten oxide (WO3) and boron oxide (B2O3) were irreversibly encapsulated into the nanocages of the Zr-based metal organic framework UiO-66, affording a hybrid material B2O3-WO3/UiO-66 by a simple microwave-assisted deposition method. The novel B2O3-WO3/UiO-66 material was systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray phosphorescence, and Fourier transform infrared (FTIR)-CO adsorption methods. It was found that WO3 and B2O3 were highly dispersed in the nanocages of UiO-66, and the morphology and crystal structure of UiO-66 were well preserved. The B2O3 species are wrapped by WO3 species, thus increasing the polymeric degree of the WO3 species, which are mainly located in low-condensed oligomeric environments. Moreover, when compared with WO3/UiO-66, the B2O3-WO3/UiO-66 material has a little weaker acidity, which decreased by 10% upon the B2O3 introduction. The as-obtained novel material exhibits higher catalytic performance in the cyclopentene selective oxidation to glutaraldehyde than WO3/UiO-66. The high catalytic performance was attributed to a proper amount of B2O3 and WO3 with an appropriate acidity, their high dispersion, and the synergistic effects between them. In addition, these oxide species hardly leached in the reaction solution, endowing the catalyst with a good stability. The catalyst could be used for six reaction cycles without an obvious loss of catalytic activity.

2013 ◽  
Vol 547 ◽  
pp. 57-69 ◽  
Sujata. S. Khot ◽  
Neelam S. Shinde ◽  
Bhimrao P. Ladgaonkar ◽  
Bharat B. Kale ◽  
Shrikant C. Watawe

Some physical properties (such as lattice parameter, curie temperature, ac susceptibility) of Mg1-xZnxFe2O4 (where x = 0.3,0.4,0.5,0.6) ferrites have been studied. Magnesium Zinc Ferrites was synthesized by oxalate co-precipitation method at different synthesis temperature and characterized by X-ray diffraction and far IR absorption techniques, scanning Electron microscopy .The lattice parameter were computed. The X-ray diffraction studies reveal the formations of single phase cubic spinel structure.IR absorption bands are observed around 600 cm-1 and 400 cm-1 on the tetrahedral and octahedral sites respectively. Magnetization parameters such as saturation magnetization, and magnetic moment were calculated and the results are discussed with the help of the existing theories. Saturation magnetization was found to be in the range 2 emu/gm to 8.28 emu/gm when the samples were synthesized below 100°C. The variation of A.C. susceptibility with temperature shows the existence of super paramagnetic nature. The Curie temperature was determined from the measurement of the susceptibility verses temperature. The SEM micrograph shows the uniform distribution of the particles, the average size was estimated to be 0. 350 µm.

2021 ◽  
Vol 35 (1) ◽  
pp. 17-29
Meral Dükkancı

Efficient decolorization of Rhodamine 6G dye (Rh 6G) using magnetic TiO2@Fe3O4/FeZSM-5 photocatalyst was carried out in a batch reactor equipped with two visible lights (high-pressure Na lamps). The photocatalyst was synthesized and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, diffuse reflectance spectroscopy and vibrating sample magnetometry. The effects of initial Rh 6G concentration, catalyst loading, and pH were investigated on photocatalytic oxidation of Rh 6G. Maximum decolorization of 98.2 % was found at optimum conditions of 20 ppm Rh 6G, 1 g L–1 of catalyst, and pH of 13.04. Central composite design was used for the optimization of photocatalytic degradation of Rh 6G. Predicted decolorization efficiencies were found to be in good agreement with experimental values with high regression coefficient of 98.8 %. In addition to color removal, the toxicity of the Rh 6G aqueous solution was significantly reduced after photocatalytic oxidation. Small reduction of activity (from 34.6 % to 30.5 %) showed the stability of the catalyst after three consecutive runs. Due to the magnetic property of the catalyst, it could be removed from the solution with the help of external magnetic field. This prevents the loss of catalyst and reduces the extra separation cost, which is desired in industrial or large-scale applications.

2018 ◽  
Vol 26 (1) ◽  
pp. 1-12 ◽  
Shashidhar N. Adarakatti ◽  
Veeresh S. Pattar ◽  
Prashant K. Korishettar ◽  
Bhagyashri V. Grampurohit ◽  
Ravindra G. Kharabe ◽  

Abstract Li-Ni ferrite has gained great scientific elicit owing to of its unparalleled properties and applications. The copper doped Li-Ni ferrite has been synthesized by sucrose method. The structure was characterized by X-ray diffraction, which has confirmed the formation of single-phase spinel structure. X-ray diffraction and FTIR data reveals the formation of cubic structure phase. Unit cell parameters vary with copper content; overall variation of the unit cell parameters obeys Vegard’s law. The main absorption bands of spinel ferrite have appeared through IR absorption spectra recorded in the range of 300–700 cm−1. The copper concentration dependence of lattice parameters obeys Vegard’s law. DC electrical resistivity of the prepared samples decreases with increasing in the temperature which shows the semiconducting behaviour of all nano ferrites. The most prominent influence copper doping on the electrical properties of Li-Ni ferrites has been reported.

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Keene Carlvin Mmusi ◽  
Sebusi Odisitse ◽  
Florence Nareetsile

The ever-increasing population growth and economic developments have heightened demand for energy. This has resulted in depletion and ever-rising prices of petroleum diesel, thus increasing environmental degradation. These complications have motivated this study for the search of an alternative eco-friendly and renewable source of energy such as biodiesel. Biodiesel has been found to be a potential alternative fuel for diesel. Biodiesel was produced by transesterification reaction of Schinziophyton rautanenii (mongongo) nut oil in the presence of a base heterogeneous catalyst: CaO derived from eggshell ash and synthesised CaO-nanoparticles (CaO-NPs). The catalysts were calcined at a temperature of 800°C for 3 h and characterized by scanning electron microscope-energy dispersive X-ray (SEM-EDX) where both catalysts showed agglomerated particles and high elemental composition of Ca and O. Powder X-ray diffraction (XRD) showed that CaO was present in both catalysts, and the average crystalline size obtained was 42 and 50 nm for CaO-NPs and eggshell ash, respectively. Fourier transmission infrared (FTIR) spectrometer showed absorption bands of CaO in both catalysts which were at 875 and 713.46 cm−1 for CaO-NPs and eggshell ash, respectively. The analysis of mongongo nut oil (MNO) and mongongo methyl esters (MMEs) was done according to the European biodiesel specification (EN 1421) and American Society for Testing and Materials (ASTM D675). Statistically, there was no significant difference between CaO-NPs and eggshell in terms of optimum yield ( P > 0.05 ) using a sample t-test. However, in terms of catalyst loading, the eggshell was a better catalyst as it required a low catalyst load to obtain an optimum yield of 83% at 6 wt.% compared to CaO-NPs with an optimum yield of 85% at 12 wt.%. The reactions were all performed at constant reaction conditions of 9 : 1 methanol to oil ratio, 3 h reaction time, and 65°C reaction temperature.

1997 ◽  
Vol 52 (6) ◽  
pp. 679-686 ◽  
Thomas Häusler ◽  
William S. Sheldrick

Abstract A metal-assisted ring expansion from the preferred solution species (EtAsO)n, n = 3,4, to the hexameric ligand (EtAsO)6 is observed for the reactions of [ReBr(CO)5], [RuCL2(Ph3P)3], RhCl3 ·3H2O and [Cu2CF3SO3)2(C6H6)] with ethylcycloarsoxane. Whereas two metal frag­ments are facially coordinated by the upper and lower three As atoms of a flattened As6O6 cuboctahedron in both [{ReBr(CO)2}2 {μ-[cyclo-(EtAsO)6]}] (1) and [Cu2{μ-[cyclo-(EtAsO)6]}(Me2PhP)2](CF3SO3)2 (4), potential ring strain restricts the reaction with the other compounds to the formation of mononuclear complexes [RuCl2{cyvclo-(EtAsO)6}(Ph3P)] (2)and [RhCl3{cyclo-(EtAsO)6}] (3) with k3As1,3,5 coordination. The structures of 1 - 4 were established by X-ray structure analysis. A shift in the ν(As-O) IR absorption bands to higher wavenumbers (830 - 788 cm-1 ) is characteristic for (EtAsO)6 complexes in comparison to those of the cyclic tetramer (781-747 cm-1 ).

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