Recent progress in metal-doped TiO2, non-metal doped/codoped TiO2 and TiO2 nanostructured hybrids for enhanced photocatalysis

The secular determinants obtained in the previous paper are solved for the energy levels which are important in the absorption spectra of the normal complex ions, leaving the crystalline field strength as a parameter. The values of B and C (Racah's parameters) there needed are determined from the observed spectra of free ions or in some cases by extrapolation. The f -values of the transitions which connect the energy levels calculated are estimated and compared with the observed intensities. The difference of the spectral width among absorption bands and lines is also considered using the energy diagram obtained. Following the assignments determined by the above considerations, the calculated positions of lines and bands are rather in good agreement with the experimental data in divalent ions [MX 6 ] 2+ (M=Cr, Mn, Fe, Co, Ni), when we adjust the crystalline field parameter D q suitably. In trivalent ions [MX 6 ] 3+ (M=Ti, V, Cr, Mn, Fe), it is necessary besides the adjustment of D q to use smaller values ...

On the absorption spectra of complex ions. II

Photoreduction of N₂ is among the most interesting and challenging methods for N₂ fixation under mild conditions. In this study, we determined that nitrogen vacancies (NVs) could endow graphitic carbon nitride (g-C₃N₄) with the photocatalytic N₂ fixation ability. Photocatalytic N₂ fixation induced by NVs is free from the interference of other gases. The reason is that NVs could selectively adsorb and activate N₂ because NVs have the same shape and size as the nitrogen atom in N₂. In addition to this, NVs could also improve many other properties of g-C₃N₄ to support photocatalytic N₂ fixation. These new findings could elucidate the design of efficient photocatalysts for photocatalytic N₂ fixation.

Selective photocatalytic N₂ fixation dependent on g-C₃N₄ induced by nitrogen vacancies

Photocatalytic application of spinel ferrite nanoparticles and nanocomposites in wastewater treatment: Review

The photocatalytic degradation of methyl orange (MO) and congo red (CR) dyes from aqueous solution have been attempted using chitosan-g-poly(acrylamide)/ZnS (ChPA/ZS) nanocomposite materials. Nanocomposites were successfully prepared in the aqueous solution through microwave radiations. Band gap property of composite was studied using UV–vis spectrophotometer. The ChPA/ZS nanocomposite was characterized by various techniques. The photocatalytic activity of ChPA/ZS was evaluated for methyl orange and congo red dyes degradation in aqueous solution under simulated solar irradiation. The degradation of dyes was recorded higher for ChPA/ZS nanocomposite. After 2 h of irradiation, 75% of congo red dye was degraded and 69% of methyl orange was degraded after 4 h of simulated solar irradiation. ChPA/ZS composite showed a higher rate of dye degradation owing to outstanding adsorbing properties of cross linked polyacrylamide.

Photocatalytic degradation of highly toxic dyes using chitosan-g-poly(acrylamide)/ZnS in presence of solar irradiation

Synthesis, enhanced optical and photocatalytic study of Cd–Zn ferrites under sunlight

In the present investigation, we have reported the fabrication of a low-cost, magnetically separable, solar light active NiFe2–xNdxO4 photocatalyst with different neodymium contents. The synthesized photocatalyst samples were characterized by a combination of various physicochemical techniques such as PXRD, SEM, EDS, FTIR, and UV–vis spectroscopy. It was observed that Nd substitution can greatly enhance absorption in the whole visible region. With an increase in Nd concentration, NiFe2–xNdxO4 samples show a red shift in absorption. Interestingly, Nd substitution into nickel ferrite results in a dramatic conversion of the inert NiFe2O4 into a highly solar light active photocatalyst for the degradation of organic pollutants and also shows excellent recyclability and durability properties. The significant enhancement in photoactivity under solar light irradiation can be ascribed to the reduction of the nickel ferrite band gap by Nd3+ substitution. Therefore, these unusual properties of NiFe2–xNdxO4 encourage...

Optical and Photocatalytic Properties of Solar Light Active Nd-Substituted Ni Ferrite Catalysts: For Environmental Protection

The nanostructured zinc-doped cobalt ferrites (Zn x Co 1−x Fe2O4 where x ranges from 0.0 to 0.6 with the step of 0.2) were prepared by combustion method using curd as a green fuel. The prepared nanoparticles were further characterized using XRD, SEM with EDAX, TEM, FTIR, UV-DRS, and luminescence spectroscopy. From the XRD, it shows that these nanomaterials exhibit average crystallite size in the range ∼ 12-21 nm with inverse cubic spinel structure. The agglomerated and spherical structure of the nanoparticles is confirmed by SEM and TEM. The vibrational stretching modes of tetrahedral (582 cm−1) and octahedral (385 cm−1) sites were confirmed by FTIR. Further, density functional theory (DFT) analysis was carried out in order to study the electronic properties of cobalt ferrite and zinc-doped cobalt ferrite nanostructures. The band gap results for pure CoFe2O4 and Zn-doped CoFe2O4 nanoparticles were closer to the experimental values. The luminescence spectrum shows peaks correspond to violet, blue, green, yellow and orange emission. The photodegradation studies of obtained nanoparticles were evaluated for the degradation of Congo red and Evans blue dyes under visible light irradiation. Pure CoFe2O4 and Zn-doped CoFe2O4 nanoparticles were inspected against both gram-positive (Staphylococcus aureus) and the gram-negative (Salmonella typhi) bacteria for antibacterial studies. The gram-negative bacterium Salmonella typhi shows high antibacterial activity with the inhibition zone of Zn-doped CoFe2O4 (22 mm) compared to pure CoFe2O4 (16 mm)

Green synthesis of zinc doped cobalt ferrite nanoparticles: Structural, optical, photocatalytic and antibacterial studies

Sugarcane juice mediated eco-friendly synthesis of visible light active zinc ferrite nanoparticles: Application to degradation of mixed dyes and antibacterial activities

In this article, a series of Sm substituted zinc spinel ferrite nanoparticles (ZnSm x Fe 2-x O 4 ) were fabricated by co-precipitation method. The effect of samarium substitution and annealing temperature on the crystal structure of zinc ferrite were explored in this study. The lattice parameter and crystallite size are increased with the increase in the Sm content. The visible light absorption ability extended as Sm content was increased up to (x = 1.5) and, which was the best optimal dosage for photocatalytic degradation of Methyl Orange (MO). This red shift in absorbance unequivocally indicates them as potential agent in solar light driven photocatalytic activity. Such enhancement can be ascribed to the diminution in the band gap of zinc ferrite upon samarium substitution (1.42 eV). Present study provides an excellent competency of rare earth substituted ferrite as a new class of photocatalyst over dye degradation under solar light irradiation.

R. Viswanath

Papers

Synthesis, enhanced optical and photocatalytic study of Cd–Zn ferrites under sunlight

Optical and Photocatalytic Properties of Solar Light Active Nd-Substituted Ni Ferrite Catalysts: For Environmental Protection

Green synthesis of zinc doped cobalt ferrite nanoparticles: Structural, optical, photocatalytic and antibacterial studies

Sugarcane juice mediated eco-friendly synthesis of visible light active zinc ferrite nanoparticles: Application to degradation of mixed dyes and antibacterial activities

Solar light responsive Sm-Zn ferrite nanoparticle as efficient photocatalyst