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Supercapacitors are perfect energy storage devices; they can be charged almost instantly and release energy over a long period. Another advantage of using supercapacitors is their multipletimes chargeable behavior with minimum degradation in performance. Herein, we report the nanoporous activated carbon based modified electrodes prepared by using phosphoric acid (PA) activation method at different temperatures (600, 700, 800, and 900 °C) using bio-waste precursor, Tamarindus indica ( T. indica ) fruit shell. Because of their excellent energy storage capacity, in the present work, supercapacitive behavior of the nanoporous activated carbon based modified electrode has been demonstrated and hence the electrochemical properties of the developed supercapacitor electrodes are analyzed using cyclic voltammetry, galvanostatic charge-discharge measurements, electrochemical impedance spectroscopy and cycling studies using 1 M KOH as the electrolyte. The developed supercapacitor nanoporous activated carbon materials are characterized by X-ray diffraction, functional group analysis, surface area and morphological studies.

Cobalt oxide nanorods were successfully synthesized by a hot plate combustion method using the plant extract of Vitis vinifera . The plant extract as an alternative to toxic chemicals can be used generally as reducing and capping agents. The obtained nanorods were characterized by XRD, FT-IR, Raman, TEM, SAED, EDX, DRS, PL and VSM techniques for the structural, morphological, optical and magnetic properties. The XRD, FT-IR, Raman, EDX analysis confirmed the high purity of the sample. The TEM and SAED results showed the rod shape morphology of the sample. DRS and PL showed the band gap energy and emission at visible region. VSM showed the antiferromagnetic nature of the sample. The photocatalytic activities of the as-prepared cobalt oxide nanorods were investigated for the degradation of textile dying waste water. As per the standards of Indian pollution control board for industrial waste water let out into river bodies, the degradation reactions of waste water was found to be 250 mg/L at 150 min. Also, the same catalyst is used for the reduction of 4-nitrophenol and 4-nitroaniline using sodium borohydride as a reducing agent and it exhibits excellent reduction reaction, because of the high active surface sites. The time taken for the reduction reaction was 300 sec and 210 sec for 4-nitrophenol and 4-nitroaniline respectively. Also, the antibacterial activities towards the bacterial strains were studied and reported.

Pure ZnO and dZnO (doped ZnO) systems of type Zn 1- x M x O (M = Co, Cu, Fe and Mn) synthesised by co-precipitation method were evaluated for DSSC studies. Tween-80, a non-ionic surfactant which was used during preparation process also acted as binder for coating the nanoparticles on the FTO glass plate. In order to reduce the band gap, transition metal dopants have been incorporated into ZnO so that it changes the photo electrochemical properties. The conduction band edge minimum (CBM) potentials and valence band edge maximum (VBM) potentials were calculated. The CBM and VBM potentials varied with different dopants. The band gap were engineered such that it shifts the conduction band minimum (CBM) to less negative potential than LUMO (Lower Unoccupied Molecular Orbital) of the dye (Rhodamine B). Pure ZnO showed highest open circuit voltage ( V oc ) of 631.7 mV and short-circuit current density ( J sc ) of 3.5031 μ A/cm². In case of dZnO, 5% doping showed highest short-circuit current density and highest power conversion efficiency for all dopants (Co, Cu, Fe and Mn). Nanoparticles with remarkable morphologies influence the efficiency of dye sensitized solar cell (DSSC). The DSSC parameters such as open circuit voltage ( V oc ), short-circuit current density ( J sc ), Fill factor (FF) and photovoltaic efficiency ( η ) was calculated. The effect and variation of CBM and VBM in DSSC parameter are discussed.

La₂CuO₄ (LCO) perovskite nanoparticle was synthesized by microwave assisted combustion method and characterized using X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transformed infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM) and energy dispersive X-ray analysis (EDX), respectively. The XRD confirmed the formation of a single orthorhombic phase. The average crystallite size of LCO samples were 39.6 nm and 46.4 nm. This LCO perovskite nanoparticle was evaluated for the conversion of methanol to formaldehyde in liquid phase batch reactor at atmospheric conditions. The conversions were studied by using different solvents like dimethyl sulfoxide (DMSO), acetonitrile, n -hexane, and temperature varying from 60 °C to 90 °C and reaction time from 1 to 4 h duration. 50 mg of catalyst, 50 mmol of DMSO, 50 mmol of methanol, temperature at 70 °C and 4 h duration was the optimized condition to achieve 100% methanol conversion and 98% selectivity of formaldehyde. The reaction pathway of methanol to formaldehyde conversion is discussed.

Hierarchical ordered ZSM-5 zeolites were successfully synthesized by a template-free hydrothermal treatment using rice joints ash as the source of silica. The formation of hierarchical ordered ZSM-5 zeolites and its physicochemical properties were investigated systematically. The mineralogical phases, morphology, surface area and porosity, acidity and thermal stability of the synthesized hierarchical materials were investigated using XRD, FT-IR, HR-SEM, N2 adsorption-desorption (BET) analysis, NH3-TPD and TGA/DTA analysis. The excellent catalytic activity of hierarchical ordered ZSM-5 zeolites (150 °C) was revealed in the selective oxidation of toluene to the corresponding benzaldehyde with 82% conversion and 94% selectivity. The material was evaluated for the oxidation of toluene in the presence of H2O2 as the oxidizing agent and 1,4-dioxane solvent. The obtained results noted that the material was highly active, stable and can be recycled at least four times without a loss of catalytic efficiency. The crystallization was carried out in an autoclave for 5 days maintained at a temperature of 150 °C for the transformation of RJA into hierarchical ZSM-5 zeolite structure as well as to achieve high crystallinity.

Nanostructured PbZr0.52Ti0.48O3 (PZT) powder was synthesized at 500 °C-800 °C using sol-gel route. X-ray diffraction and Rietveld analysis confirmed the formation of perovskite structure. The sample heat treated at 800 °C alone showed the formation of morphotropic phase boundary with coexistence of tetragonal and rhombohedral phase. The PZT powder and PVDF were used in 0-3 connectivity to form the PZT/PVDF composite film using solvent casting method. The composite films containing 10%, 50%, 70% and 80% volume fraction of PZT in PVDF were fabricated. The XRD spectra validated that the PZT structure remains unaltered in the composites and was not affected by the presence of PVDF. The scanning electron microscopy images show good degree of dispersion of PZT in PVDF matrix and the formation of pores at higher PZT loading. The quantitative analysis of elements and their composition were confirmed from energy dispersive X-ray analysis. The optical band gap of the PVDF film is 3.3 eV and the band gap decreased with increase in volume fraction of PZT fillers. The FTIR spectra showed the bands corresponding to different phases of PVDF (α, β, γ) and perovskite phase of PZT. The thermogravimetric analysis showed that PZT/PVDF composite films showed better thermal stability than the pure PVDF film and hydrophobicity. The dielectric constant was measured at frequency ranging from 1 Hz to 6 MHz and for temperature ranging from room temperature to 150 °C. The composite with 50% PZT filler loading shows the maximum dielectric constant at the studied frequency and temperature range with flexibility.

We report the fabrication of tuned band gap quantum dots sensitized LaB₆ hybrid nanostructures and their application as a photoanode for photoelectrochemical water splitting. The lanthanum hexaboride (LaB₆) obtained by molten salt electrolysis method is sensitized with different sized CdSe quantum dots, which form a multiple-level hierarchical heterostructure and such design enhance the light absorption and charge carrier separation, which in turn showed higher photocurrent density compared to that of pristine LaB₆. When LaB₆ is sensitized with CdSe quantum dots of different band gaps, which have the absorption in the green and red (530 and 605 nm) regions in visible light, developed a ten times higher photocurrent density (11.0 mA cm(−2)) compared to that of pristine LaB6 (0.5 mA cm(−2) at 0.75 V vs. Ag/AgCl) in 1 M Na₂S electrolyte under illumination. These results prove that the tuned band gap quantum dots sensitized LaB₆ heterostructures are an ideal candidate for a photoanode in solar water splitting applications.

Pure and Fe-doped ZnO nanostructures with different weight ratios (0.5, 1.0, 1.5, and 2.0 at wt% of Fe) were successfully synthesized by a facile microwave combustion method using urea as a fuel. The detailed structural characterization was performed by means of X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). XRD patterns refined by the Rietveld method indicated that Fe-doped ZnO have a single pure phase with wurtzite structure, suggesting that Fe ions are successfully incorporated into ZnO crystal lattice by occupying Zn ionic sites. Interestingly, the morphology was found to change substantially from grains to nanoflakes and then into nanorods with the variation of Fe-content. The optical band gap estimated using DRS was found to be red-shifted from 3.220 eV for the pure ZnO nanostructures, then decreases up to 3.200 eV with increasing Fe-content. Magnetic studies showed that Fe-doped ZnO nanostructures exhibit room temperature ferromagnetism (RTFM) and the saturation magnetization attained a maximum value of 8.154 x 10(-3) emu/g for the highest Fe-content. The antibacterial activity of pure and Fe-doped ZnO nanostructures against a Gram-positive bacteria and Gram-negative bacteria was investigated. Pure ZnO and Fe-doped ZnO exhibited antibacterial activity, but it was considerably more effective in the 1.5 wt% Fe-doped ZnO nanostructures.

CO²⁺ doped manganese ferrite (Mn₁₋xCoxFe₂O₄, x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) samples were synthesized by a microwave combustion method. Nitrates of the constituent elements and urea were respectively used as the oxidizer and fuel to drive the reaction. On an average a yield of 80% were obtained for all the compositions. Light-absorbing properties from UV-Vis diffuse reflection spectrum were studied and the results infer that the band gap energy (Eg) of the pure MnFe2O4 is 1.76 eV and with increase in C02+ ion concentration, it increases to 2.25 eV. The phase purity and crystal lattice symmetry were estimated from X-ray diffraction (XRD) and was identified as the spinel cubic crystal structure. The lattice parameter is found to decrease with an increase in Co content. The crystallite size was in the range of 19-25 nm. The purity and the composition of the elements were further confirmed by energy dispersive X-ray (EDX) results. Microstructural features obtained by scanning electron microscope (SEM) demonstrate that the nanocrystals were formed with a decrease in average grain size with C02+ content. Room temperature magnetic measurement for stoichiometric samples is discussed with the help of vibrating sample magnetometer (VSM). The saturation magnetization (M), remanant magnetization (Mr) and coercivity (H.) are measured from the respective hysteresis plots.

Pure and cobalt doped zinc ferrites were prepared by microwave combustion method using L-arginine as a fuel. The prepared samples were characterized by various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, Fourier transformed infrared (FT-IR) spectroscopy, photoluminescence spectroscopy and UV-Visible diffuse reflectance spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis confirmed the formation of zinc ferrites normal spinel-type structure with an average crystallite sizes in the range, 25.69 nm to 35.68 nm. The lattice parameters decreased as cobalt fraction was increased. The HR-SEM images showed nanoparticles are agglomerated. The estimated band gap energy value was found to decrease with an increase in cobalt content (1.87 to 1.62 eV). Broad visible emissions are observed in the photoluminescence spectra. A gradual increase in the coercivity and saturation magnetization (M(s)) were noted at relatively higher cobalt doping fractions.

Pure and M-doped (Ba, Ce, Mg) ZnO spherical nanoparticles are synthesized by a simple low temperature co-precipitation method, and were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), and high resolution transmission electron microscopy (HR-TEM). The XRD results showed the formation of single phase ZnO with wurtzite crystal structure and the electron microscopic studies supported the validity for the formation of pure and M-doped (Ba, Ce, Mg) ZnO spherical nanoparticles. Photocatalytic degradation (PCD) of 2,4,6-trichlorophenol, a potent endocrine disrupting chemical in aqueous medium was investigated by both pure and M-doped (Ba, Ce, Mg) ZnO spherical nanoparticles under UV-light irradiation. The influence of the metal dopants on the structure and photocatalytic (PC) activity of ZnO was investigated systematically. Furthermore, the effect of different parameters such as 2,4,6-trichlorophenol concentration, photocatalyst amount, pH and dopant wt% on the resulting PC activity was investigated. The kinetics of the photocatalytic degradation of 2,4,6-trichlorophenol was found to follow the pseudo-first order reaction, and it was established that Ba-doped ZnO is photocatalytically more active than the other photocatalysts.

Sphere/rod-like α-Fe2O3 nanostructure were successfully synthesized by simple surfactant-free precipitation route. The as-prepared samples were characterized by X-ray powder diffraction (XRD) to determine the phase purity and the crystal structure. The lattice parameter and crystallite size of the samples have been calculated from the Rietveld analysis. The crystallite size has been compared by Scherrer's formula and Rietveld method and both method showed increase of the grain size with the increase of the calcined temperature. The crystallite size was in the range of 5-30 nm. The high resolution scanning electron microscopy (HR-SEM) analysis of the samples shows that the morphology of the nanostructures changed from nanospheres into nanorods and it was confirmed by high resolution transmission electron microscopy (HR-TEM). Energy dispersive X-ray (EDX) analysis reveals the presence of O and Fe elements only. The optical properties of the as-prepared nanostructures were determined by photoluminescence (PL) spectra. The band gap energy was investigated by UV-Visible diffuse reflectance spectra (DRS) and calculated by means of the Kubelka-Munk method. The band gap values are decreased from 2.26 eV to 2.17 eV as the temperature increased from 300 degrees C to 400 degrees C with increasing the crystallite size. A Vibrating Sample Magnetometer (VSM) was used to study the magnetic properties of iron oxide (α-Fe2O3) nanostructures. Magnetic hysteresis (M-H) loops revealed that the as-prepared α-Fe2O3 samples displayed ferromagnetic behavior.

A novel self-assembled pure and Ce doped ZnO nano-particles (NPs) were successfully synthesized by a simple low temperature co-precipitation method. The prepared photocatalysts were characterized by X-ray diffraction (XRD), High resolution scanning electron microscopy (HR-SEM), High resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The results indicated that the prepared photocatalysts shows a novel morphology, high crystallinity, uniform size distribution, and more defects. Photocatalytic degradation (PCD) of nonylphenol, a potent endocrine disrupting chemical in aqueous medium was investigated. Higher amount of oxygen defects exhibits enhanced PCD of nonylphenol. In addition, the influence of the Ce contents on the structure, morphology, absorption, emission and photocatalytic activity of ZnO nanoparticles (NPs) were investigated systematically. The relative PCD efficiency of pure ZnO, Ce-doped ZnO NPs and commercial TiO2 (Degussa P-25) have also been discussed.

In the present study, ZnO nanoparticles (ZNPs) and nanoflakes (ZNFs) were prepared by conventional combustion method and microwave combustion method, respectively. The structural phase and morphology were investigated by using X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM). The crystallite size was calculated using Scherrer formula, and it lies in the range of 20-21 nm for ZNFs and 23-28 nm for ZNPs. The elemental analysis was investigated by energy dispersive X-ray analysis (EDX). Also, absorbance and emission spectra were measured by using diffuse reflectance (DRS) and photoluminescence (PL) studies. The band gap was measured using Kubelka-Munk model and it shows 3.47 eV for ZNFs and 3.26 eV for ZNPs. A fill factor (FF) of 0.57, short-circuit current (J(sc)) of 8.02 mA/cm2, open-circuit voltage (V(oc)) of 0.70 V and an overall light to electricity conversion efficiency (eta) of 1.62% were obtained from the dye-sensitized solar cell (DSSCs) based on ZNFs.

Dye-sensitized solar cells (DSSCs) based on ZnO nanostructures with two different morphologies, such as nanowires (ZNWs) and nanoparticles (ZNPs), were synthesized by microwave combustion (MCM) and conventional combustion (CCM) method. The obtained ZnO nanostructures were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of hexagonal wurtzite ZnO. The crystallite size of the ZnO nanostructures was calculated using Sherrer's formula. The formation of ZNWs and ZNPs was confirmed by HR-SEM and HR-TEM. The optical absorption and PL emissions were determined by DRS and PL spectra respectively. ZnO nanostructures with band gap energies of 3.36 eV (MCM) and 3.25 eV (CCM) were obtained. The dye-sensitized ZnO nanowire arrays exhibit much stronger optical absorption as compared with ZnO nanoparticle arrays, suggesting that the larger surface area improves light harvesting. The dye-sensitized solar cell based on the optimized ZnO nanowires array reaches a conversion efficiency of 1.73%, which is higher than that obtained from ZnO nanoparticles (0.69%) under the light radiation of 1000 W/m2. As-prepared ZNWs have potential applications in fabricating next generation nanodevices.

In this study, pure and Co-doped CuO nanostructures (0.5, 1.0, 1.5, and 2.0 at wt% of Co) were synthesized by microwave combustion method. The prepared samples were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). Powder X-ray diffraction patterns refined by the Rietveld method indicated the formation of single-phase monoclinic structure. The surface morphology and elemental analysis of Co-doped CuO nanostructures were studied by using HR-SEM and EDX. Interestingly, the morphology was found to change considerably from nanoflowers to nanoplates then to nanoparticles with the variation of Co concentration. The optical band gap calculated using DRS was found to be 2.1 eV for pure CuO and increases up to 3.4 eV with increasing cobalt content. Photoluminescence measurements also confirm these results. The magnetic measurements indicated that the obtained nanostructures were ferromagnetic at room temperature with an optimum value of saturation magnetization at 1.0 wt.% of Co-doped CuO, i.e., 970 micro emu/g.

There is a growing concern for the development of alternative environment friendly sustainable methods for the preparation of nanomaterials. Phytosynthesis of nano zinc aluminate by a microwave method using high purity metal nitrates and Sesamum (Sesamum indicum L.) extract is reported in this work. Sesamum (Sesamum indicum L.) extract simplifies the process and provides an alternative method for a simple and economical way of synthesis of nano zinc aluminate. It is also prepared by conventional method for comparison purpose. The obtained nanomaterials were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption isotherms, diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The formation of pure zinc aluminate phase is confirmed by XRD and FT-IR. The change in morphology from nanoplates to nanoporous sheets from the conventional to microwave heating method is clearly shown by HR-SEM. UV-Visible diffuse reflectance spectroscopy (DRS) studies revealed the band gap energy of ZnAl2O4 nanoplates and nanoporous sheets as 4.0 to 4.2 eV respectively. Photoluminescence (PL) emissions are centered at around 480, 519 and 545 nm, respectively. ZnAl2O4 nanoporous sheets prepared by microwave method showed better catalytic activity for the oxidation benzyl alcohol (90%) than ZnAl2O4 nanoplates prepared by conventional method (51%).

The effect of ethylenediamine addition in the sol-gel method for the preparation of pure and Sr(II)-added nano copper aluminate (CuAl2O4) composites for the enhancement in their structural, electrical, and alcohol sensing properties were investigated. The effect of addition of Sr(II) to pure CuAl2O4 in both the methods were also discussed. X-ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption isotherms, temperature dependant conductance measurements and thermoelectric power measurements were used to characterize the composites prepared. Among the composites, 0.8 molar ratio strontium added copper aluminate composite prepared by modified sol-gel method showed the highest sensitivity towards alcohols. The stability, response and recovery of MS-CuSA5 were also discussed. The response and recovery characteristics showed that the order of sensing alcohols by the composites was butanol > isopropanol > ethanol > methanol, which could be explained on the basis of oxidation of alcohols.

The hexagonal ZnO nanorods supported activated carbon (ZSAC) was successfully prepared using zinc nitrate hexahydrate and urea through microwave irradiation. The method of preparation is simple and cost effective. The activated carbon (AC) with high surface area (446.44 m2/g), pore volume (00.21 cm3/g) and average pore diameter (01.89 nm) was employed as a matrix support for the growth of ZnO nanorods. The XRD results affirm the formation of wurtzite ZnO nanostructures. The FT-IR studies disclose the presence of varied functional groups present in ZSAC. The HR-SEM images reveal the pore morphology of AC and hexagonal shape of ZnO nanorods formed. The E(g) value obtained from Kubelka-Munk transformed reflectance spectra is about 3.43 eV. The photoluminescence emissions reveal the defects in the crystal lattice. The ZSAC thus prepared would perform substantial role in the area of catalysis.

Nanosized zirconium oxide (ZrO2) powders were synthesized by the microwave combustion synthesis (MCS) using glycine as the fuel without using any template, catalyst or surfactant. For the purpose of comparison, it was also prepared using solution combustion synthesis (SCS). The as-synthesized ZrO2 was characterized by X-ray powder diffraction (XRD), Fourier Transform infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of cubic phase ZrO2. FT-IR was used to investigate the adsorption of water and CO2 on ZrO2 surface and confirm the formation of Zr-O phase. The formation of ZrO2 nanospheres was confirmed by HR-SEM and TEM and their possible formation mechanisms were also proposed. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra respectively.

In the present work, we report simple and eco-friendly route to synthesise biocomposite doped nanocrystalline MgO. The seed of Hygrophila spinosa T. Anders (HST) plant showing gelly nature in water and contain several minerals, is the chosen dopant (biocomposite). The structural parameters, functional groups, surface morphology, elemental analysis and optical behavior of the prepared samples were evaluated by using X-ray diffraction (XRD), Fourier transform-infra red (FT-IR), high resolution scanning electron microscope (HR-SEM), Energy dispersive X-ray analysis (EDX), Diffuse reflectance spectroscopy (DRS) techniques respectively. The two probe DC-electrical resistance method was used to evaluate the sensitivity factor (S(f)) of the prepared samples at different humidity levels. It was found that the appropriate ratio of dopant into MgO extensively modified the sensitivity. Compared to all the other composition of Mg:HS, the sensitivity factor (S(f)) of MH3 (0.25:0.75) is found to be higher i.e., 3,300. The MH3 sample also showed good linearity, reproducibility, stability, response and recovery time about 210 +/- 5 s and 232 +/- 4 s, respectively. The composition, crystallite size and surface area were found to have the significant effects on the sensitivity.

A series of Sr(II)-added nickel aluminate nanocatalysts with different molar ratios of Ni:Sr (1.0:0.0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4 and 0.5:0.5) keeping the molar ratio of aluminum constant were synthesized by modified sol-gel method using ethylenediamine and sintered at 900 degrees C. The samples were labeled as NiSA1-900, NiSA2-900, NiSA3-900, NiSA4-900, NiSA5-900, NiSA6-900, respectively. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption isotherms and tested for the catalytic oxidation of benzyl alcohol. Influence of the reaction parameters (molar ratio of Sr(II) added to nickel aluminate nanocatalyst, reaction time, reaction temperature and solvent effect) on the catalytic oxidation of benzyl alcohol were studied. It was observed that the addition of Sr(II) improves the performance of the nickel aluminate nanocatalysts towards the selective oxidation of benzyl alcohol and decreases the grain size. Higher activity was obtained for the conversion of benzyl alcohol to benzaldehyde for 0.3 molar percentage Sr(II) added nickel aluminate catalyst (NiSA4-900). Stability and reusability of the catalyst was also investigated.

Porous Zn(1-x)Cu(x)Al2O4 (x = 0, 0.1,0.2, 0.3, 0.4, 0.5) spinel nanostructures were synthesized by one-pot microwave combustion technique. All the samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and scanning electron microscopy (SEM). The XRD patterns confirm the formation of single phase ZnAl2O4 without any impurities. The results of XRD indicated the average crystallite size in the range of 12.44-22.86 nm. FT-IR spectra show the vibrational stretching frequencies corresponding to the zinc aluminate spinel structure. The estimated band gap of undoped ZnAl2O4 was 4.96 eV indicating the quantum confinement phenomenon. DRS spectra also indicated the band gap narrowing effect with increase in copper ion concentrations. The defect centers acting as trap levels were obtained from photoluminescence studies responsible for the emission spectra. SEM images showed the features of well created pore structures in all the matrices. The percentage porosity of zinc aluminate matrices decreased with increasing copper doping.

Porous iron oxide (alpha-Fe2O3) nanoparticles were synthesized by the microwave combustion method (MCM) using urea as the fuel. For the purpose of comparison, it was also prepared using the conventional combustion method (CCM). The as-synthesized porous alpha-Fe2O3 nanoparticles were characterized by X-ray powder diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM) analysis. The XRD results confirmed the formation of rhombohedral alpha-Fe2O3 phase. The formation of alpha-Fe2O3 nanoparticles was confirmed by HR-SEM and HR-TEM, and their possible formation mechanisms were also proposed. The optical absorption and the band gap were determined by DRS spectra. The surface area was derived from the nitrogen adsorption-desorption isotherms using BET analysis. The magnetic properties of the synthesized alpha-Fe2O3 were investigated with vibrating sample magnetometer (VSM) and their hysteresis loops were obtained. Both the prepared samples show ferromagnetic behavior with hysteresis curve at room temperature. The relatively high saturation magnetization (65.23 emu/g) of alpha-Fe2O3-MCM suggests that this method is suitable for preparing high-quality nanocrystalline magnetic alpha-Fe2O3 for practical applications.