Review on the improvement of the photocatalytic and antibacterial activities of ZnO

Photocatalysis is a green technology which converts abundantly available photonic energy into useful chemical energy. With a rapid rise of flow photoreactors in the last decade, the design and development of novel semiconductor photocatalysts is happening at a blistering rate. Currently, developed synthetic approaches have allowed the design of diverse modified/unmodified semiconductor materials exhibiting enhanced performances in heterogeneous photocatalysis. In this review, we have classified the so far reported highly efficient modified/unmodified semiconductor photocatalysts into four different categories based on the elemental composition, band gap engineering and charge carrier migration mechanism in composite photocatalysts. The recent synthetic developments are reported for each novel semiconductor photocatalyst within the four different categories, namely: pure semiconductors, solid solutions, type-II heterojunction nanocomposites and Z-scheme. The motivation behind the synthetic upgrading of modified/unmodified (pure) semiconductor photocatalysts along with their particular photochemical applications and photoreactor systems have been thoroughly reviewed.

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Nanostructured materials for photocatalysis

Comparison of modification strategies towards enhanced charge carrier separation and photocatalytic degradation activity of metal oxide semiconductors (TiO2, WO3 and ZnO)

The family of oxide glasses is very wide and it is continuously developing. The rapid development of advanced and innovative glasses is under progress. Oxide glasses have a variety of applications in articles for daily use as well as in advanced technological fields such as X-ray protection, fibre glasses, optical instruments and lab glassware. Oxide glasses basically consist of network formers, such as borate, silicate, phosphate, borosilicate, borophosphate, and network modifiers such as alkali, alkaline earth and transition metals. In the present review article, Raman spectroscopy results for the structures of borate, silicate, phosphate, borosilicate, borophosphate, aluminosilicate, phosphosilicate, alumino-borosilicate and tellurite glasses are summarized.

A review of the structures of oxide glasses by Raman spectroscopy

Metal oxides have been of great importance to the development of energy conversion and storage technologies including heterojunction solar cells, Li-ion batteries, and electrocatalysts/photocatalys...

Electrochemical Impedance Spectroscopy of Metal Oxide Electrodes for Energy Applications

Optical and spectroscopic properties of Eu-doped tellurite glasses and glass ceramics

Judd–Ofelt analysis and improvement of thermal and optical properties of tellurite glasses by adding P2O5

Effect of heat treatment on the structural and optical properties of tellurite glasses doped erbium

Tellurite glasses with the molar composition (89-x) TeO 2 –10TiO 2 –1Nd 2 O 3 –xWO 3 (x = 0, 10 and 20 mol%) were prepared by the conventional melt-quenching technique. The effects of WO 3 concentration on the structural, thermal and optical properties of tellurite glasses have been discussed. From the differential scanning calorimetry measurements, thermal properties such as glass transition temperature T g , crystallization temperature T x , and thermal stability ΔT are estimated. It was found that ΔT increases with the increase of WO 3 composition which can indicate a reinforcement of the glassy network. Both Raman and FTIR results show that the addition of WO 3 induced a depolymerisation of tellurite glass since the Te–O–Te inter-chain linkages are progressively substituted by stronger Te–O–W bridges that are at the origin of the increase of the thermal stability of the glass. The optical band gap energy values corresponding to the direct and indirect allowed transitions and the Urbach energy values of the prepared tellurite glasses have been calculated from optical absorption edges. The results show an important decrease of the optical band gap with the increase of WO 3 concentration. It was assigned to W 6 + ions that could have a role as network modifier. The Urbach energy was found to decrease with WO 3 compositions which suggest the possibility of long range order. The refractive index and extinction coefficient were obtained by spectroscopic ellipsometry. Higher values for the refractive index are recorded due to the high polarizability of non-bridging oxygen. It is observed also that the refractive index, n increases with increasing WO 3 content. It is established that there is a trend by which the energy gap decreases with increasing refractive index and increasing the polarizability of the oxide ions. The complex dielectric function e, relative to each sample, was estimated from regression analysis. The material studied here has potential application as optical fiber.

Habib Elhouichet

Papers

Optical and spectroscopic properties of Eu-doped tellurite glasses and glass ceramics

Judd–Ofelt analysis and improvement of thermal and optical properties of tellurite glasses by adding P2O5

Effect of heat treatment on the structural and optical properties of tellurite glasses doped erbium

Investigations of thermal, structural and optical properties of tellurite glass with WO3 adding

Investigations on electrical conductivity and dielectric properties of Na doped ZnO synthesized from sol gel method