Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

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A review on the visible light active titanium dioxide photocatalysts for environmental applications

X-ray analysis of ZnO nanoparticles by Williamson–Hall and size–strain plot methods

X-ray diffraction analysis by Williamson-Hall, Halder-Wagner and size-strain plot methods of CdSe nanoparticles- a comparative study

Zinc oxide nanoparticles (ZnO-NPs) were synthesized via a solvothermal method in triethanolamine (TEA) media. TEA was utilized as a polymer agent to terminate the growth of ZnO-NPs. The ZnO-NPs were characterized by a number of techniques, including X-ray diffraction analysis, transition electron microscopy, and field emission electron microscopy. The ZnO-NPs prepared by the solvothermal process at 150°C for 18 hours exhibited a hexagonal (wurtzite) structure, with a crystalline size of 33 ± 2 nm, and particle size of 48 ± 7 nm. The results confirm that TEA is a suitable polymer agent to prepare homogenous ZnO-NPs.

/pdf/synthesis-and-characterization-of-a-narrow-size-distribution-433ra8y9no.pdf

Synthesis and characterization of a narrow size distribution of zinc oxide nanoparticles.

Green synthesis of nanoparticles by biological systems especially plant extracts has become an emerging field in nanotechnology. In this study, zinc oxide nanoparticles were synthesized using Lauru...

https://www.tandfonline.com/doi/pdf/10.1080/17518253.2018.1547925

Green synthesis of zinc oxide nanoparticles: a comparison

https://profdoc.um.ac.ir/articles/a/1019188.pdf

Effects of annealing temperature on some structural and optical properties of ZnO nanoparticles prepared by a modified sol–gel combustion method

https://profdoc.um.ac.ir/articles/a/1011153.pdf

Synthesis and structure of PMN–PT ceramic nanopowder free from pyrochlore phase

Zn1-xMnxO (x = 0, 0.02, 0.06, 0.10, 0.15) nanopowders were synthesized by the sol–gel technique calcinated at low temperatures. By decreasing the grain size in ZnO, the solubility of magnetic impurity has been increased and no detectable secondary phases were observed even in the high Mn-doping samples. The phase formation, size and morphology of nanoparticles were investigated using X-ray diffraction and SEM observations. The samples were ferromagnetic and the Curie point was found in the range 150–170 K for Zn0.94Mn0.06O and 135–150 K for Zn0.98Mn0.02O. Optical characterization and the effect of doping were carried out by means of Fourier transform infrared (FTIR) spectroscopy. Kramers–Kronig analysis was employed to evaluate the optical constants of pure ZnO and ZnO:Mn nanopowders.

/pdf/synthesis-and-structure-of-pure-and-mn-doped-zinc-oxide-3cn2n24lab.pdf

SYNTHESIS AND STRUCTURE OF PURE AND Mn-DOPED ZINC OXIDE NANOPOWDERS

The electronic structure, total density of states DOS and electronic density in ferroelectric tetragonal crystal BaTiO3 are studied using WIEN2k package. This employs the full potential-linearized augmented plan wave FP-LAPW method in the framework of the density functional theory DFT with the generalized gradient approximation (GGA). The results show an indirect band gap of 2.30 eV at the Γ point in the Brillouin zone. The calculated band structure and density of states of BaTiO3 agree with the previous experimental and theoretical results, as do the charge distribution and the prediction of the nature of the chemical bonding.

/pdf/band-structure-of-tetragonal-batio3-1rphqbesvj.pdf

Band structure of tetragonal BaTiO3

The optical properties of PbTiO3 were studied from first principles 
using the density functional theory. The dielectric functions and optical 
constants are calculated using the full potential–linearized augmented 
plane wave (FP-LAPW) method with the generalized gradient approximation 
(GGA). The theoretical calculated optical properties and energy loss (EEL) 
spectrum yield a static refractive index of 2.83 and a plasmon energy of 
23.1 eV for cubic phase. The effective electron number at low energy 
saturates near 20 eV with the value of 18.1 for the effective electron 
number. In the tetragonal phase the static refractive index decreases to 
2.59 and yields a plasmon energy of 22.7 eV.

S. M. Hosseini

Papers

Effects of annealing temperature on some structural and optical properties of ZnO nanoparticles prepared by a modified sol–gel combustion method

Synthesis and structure of PMN–PT ceramic nanopowder free from pyrochlore phase

SYNTHESIS AND STRUCTURE OF PURE AND Mn-DOPED ZINC OXIDE NANOPOWDERS

Band structure of tetragonal BaTiO3

First-principles study of the optical properties of PbTiO3