J. R. Reddy

Synthesis, Characterization and Photocatalytic Activity of KAl0.33W1.67O6 and Sn0.5Al0.33W1.67O6xH2O

Nano sized defect pyrochlore, KAl0.33W1.67O6 (KAW), is prepared through sol–gel method. Divalent tin‐doped KAW is obtained at room temperature by ion exchange method using acidified SnCl2 and parent KAW. These materials are characterized by powder X‐ray diffraction, thermogravimetric analysis (TGA), scanning electron microscopy—energy dispersive spectra (SEM‐EDS), Raman Spectroscopy and X‐ray photo electronic spectroscopy. The composition of tin‐doped KAW is obtained from chemical analysis, SEM‐EDS and TGA methods and written as Sn0.5Al0.33W1.67O6 xH2O (x = 1.4–1.5) (SnAW). It crystallizes in cubic lattice with Fd3¯m space group. The band gap energies are found to be 2.82 and 2.21 eV for KAW and SnAW respectively. The observed reduction in the band gap with the introduction of Sn2+ in defect pyrochlore lattice is due to mixing of 5s state of Sn2+ with O 2p states leading to an upward shift in the valence band. The Raman spectra of these materials gave more bands than the number expected for defect pyrochlores due to substitutional disorder in 16c sites and displacive disorder of A ions. The photoactivity of SnAW is higher compared to KAW.

Metathesis synthesis, characterization, spectral and photoactivity studies of Ln2/3MoO4 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y)

Abstract Rare earth ortho-oxomolybdates of composition Ln2/3MoO4 (Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y) were prepared by metathesis reaction. All these materials were characterized by powder X-ray diffraction, Fourier transform-infrared spectroscopy (FT-IR) and UV-Vis diffuse reflectance spectra. The Rietveld analysis of all the samples was carried out to obtain the unit cell parameters and reliability factors. All the materials were crystallized in tetragonal lattice with I41/a space group. The infrared spectra of all the samples were characterized by bands due to MoO42– units. The bandgap energies of all the samples were obtained from UV-Vis DRS spectra. The luminescence spectra of Ln2/3MoO4 (Ln=Pr, Eu and Dy) showed characteristic transitions of the rare earth ions. The visible light photocatalytic activity of all the samples was studied against degradation of methylene blue.

Preparation, characterization and photocatalytic studies of Cu2+, Sn2+ and N3− substituted K5Sb5P2O20

AbstractPotassium antimony phosphates (K-Sb-P-O) exhibit different structural networks and therefore they were studied as photocatalysts in the present investigation. K5Sb5P2O20 was prepared by solid state method. Metal ions (Cu2+ and Sn2+), and non-metal anion, N 3−, were substituted into the K5Sb5P2O20 for possible enhancement of photocatalytic activity. The precursor and substituted compounds were characterized by powder X-ray diffraction, FT-IR, SEM-EDS and UV-Vis diffuse reflectance spectra. Nitrogen substitution into K5Sb5P2O20 lattice was studied by O-N-H and XPS measurements. The photocatalytic activity of all the compounds was studied by degradation of methylene blue and methyl violet. The ion-substituted K5Sb5P2O20 have shown higher photocatalytic activity against both the dyes. The role of reactive intermediate species produced in the photocatalytic reaction was studied using their appropriate scavengers. Graphical AbstractThe red shift observed in the UV-Vis diffuse reflectance spectra of ion (Cu2+, Sn2+ and N3- ) substituted Potassium antimony phosphate (K5Sb5P2O20) indicate the mixing of Cu 3d, Sn 5s and N 2p orbitals with valence band O 2p orbital, which form (Cu 3d + O 2p), (Sn 5s + O 2p) and (N 2p + O 2p) hybrid orbitals, respectively. Higher photocatalytic activity was observed in the ion substituted materials.

Enhanced photoactivity of antimony phosphates by substitution of H+, Cu2+ and N3− in the K3Sb3P2O14·xH2O crystal lattice

Abstract Substitutional doping of framework heteroatoms in photocatalysis is one of the approaches for harvesting visible light. Tunnel structure potassium antimony phosphate (K3Sb3P2O14·xH2O) and Cu2+, H+ , and N3- substituted K3Sb3P2O14·xH2O were prepared. These materials were characterized by powder X-ray diffraction, energy dispersive spectra, infrared spectra, and UV–Vis diffuse reflectance spectra. All these compositions were crystallized in the rhombohedral crystal lattice with

Photocatalytic and Conductivity Studies of Bi3+Substituted La2Zr2O7

R\overline{3} m

Synthesis, Characterization and Photocatalytic Activity of Ag+ - and Sn2+ -Doped KTi0.5 Te1.5 O6

R3¯m space group. The absorption edges of doped compositions were shifted to longer wavelength region considerably upon substitution of Cu2+, H+ , and N3−. The photocatalytic activity of these materials was tested against the degradation of methyl violet. The higher visible light photocatalytic activity of doped K3Sb3P2O14·xH2O compositions compared to parent material was discussed. N3−-doped K3Sb3P2O14·xH2O photocatalyst is stable even after the fourth cycle of photodegradation.

Photocatalytic degradation of organic dyes with Sn 2+ - and Ag + -substituted K 3 Nb 3 WO 9 (PO 4 ) 2 under visible light irradiation

Single source precursor, antimony potassium tartrate, was used for the preparation of Sb2O3, KSb3O5, K0.51Sb0.67IIISb2VO6.26, and KSbO3. Antimony trioxide (Sb2O3) was prepared by hydrothermal method, while potassium antimony oxides (KSbO3, K0.51Sb0.67IIISb2VO6.26, and KSbO3) were obtained from the thermal decomposition of antimony potassium tartrate. All the compounds were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR), UV–Vis diffuse reflectance spectra, and scanning electron microscopy (SEM). The decomposition process of antimony potassium tartrate with temperature was given. The product formation at different temperatures of thermal decomposition was monitored by PXRD and FT-IR. The TG profile of antimony potassium tartrate shows mass loss at three regions. The infrared spectra of parent and decomposed products gave characteristic Sb-O bands. The band gap energy of decomposed products was obtained. The SEM diagrams of Sb2O3 show different morphologies. Direct solid state preparation of KSb3O5 and K0.51Sb0.67IIISb2VO6.26 under identical experimental conditions was unsuccessful.

Photocatalytic degradation of organic dyes with Sn2

ABSTRACT Trivalent bismuth substituted La2Zr2O7 pyrochlores of compositions La2-xBixZr2O7 (x = 0.2, 0.4 and 0.6) have been prepared by sol-gel method. All the samples were characterized by powder X-ray diffraction, IR spectroscopy, and SEM-EDS. These materials were found to crystallize in cubic lattice with space group . The unit cell parameters were deduced from the Rietveld refinement. The dc conductivity of all samples was measured in the temperature range 200–700°C. The photocatalytic activities of the samples were studied against methylene blue decomposition under sunlight. La2-xBixZr2O7 compounds showed enhanced photoactivity compared to La2Zr2O7.