Houcine Bouzid

Synthesis of mesoporous ceria/titania thin films for self-cleaning applications

CeO2/TiO2 thin films with a three-dimensional (3D) cubic structure were synthesized. Firstly, mesostructured 3D TiO2 films with high surface area and thermally stable have been prepared. Secondly, CeO2 was deposited on 3D mesoporous TiO2 film by two pathways: (i) cerium nitrate sol in presence of poly(ethylene glycol) was deposited on the prepared mesoporous TiO2 films by spin-coating to obtain 1, 3, and 5 layers CeO2/TiO2 and (ii) the second pathway, for thick CeO2, the prepared mesoporous TiO2 films were suspended into the high concentration of cerium nitrate in presence of poly(ethylene glycol) for 24h with magnetic stirring. FE-SEM images of the mesoporous CeO2/TiO2 films were crack-free and indicated a random worm-like network of the mesopores. The XRD patterns show for all prepared samples only TiO2 anatase phase. At five layers CeO2/TiO2, a weak and diffuse diffraction peak arises, corresponding to (111) plane of cubic CeO2. Methylene blue degradation was conducted to characterize the photocatalytic activity of films and compared with that of commercially available Pilkington Activ™ glass by the determination of their photonic efficiencies. Photonic efficiency of mesoporous TiO2~3.39% is higher than Pilkington Activ™ glass~10 times, probably due to the much larger surface area of the mesoporous films and its high crystallinity. Five layers CeO2/TiO2 films showed two times higher photoactivity for MB oxidation than mesoporous TiO2 film, and its photonic efficiency was found to be ~20 times higher than Pilkington Activ™ glass. Five layers CeO2/TiO2 was fixed after being used repetitively for five times.

Sensitive and fast response ethanol chemical sensor based on as-grown Gd2O3 nanostructures

Abstract Well crystalline gadolinium oxide (Gd 2 O 3 ) nanostructures were grown by annealing the hydrothermally as-prepared nanostructures without using any template. Microscopic studies of Gd 2 O 3 nanostructures were recorded along the [111] direction due to the clearly resolved interplanar distance d (222) ∼0.31 nm of the cubic crystal structure Gd 2 O 3 . Sensing mechanism of Gd 2 O 3 as efficient electron mediator for the detection of ethanol was explored. As-fabricated sensor demonstrated the high-sensitivity of ∼0.266 μAm/M/cm 2 with low detection limit (∼52.2 μmol/L) and correlation coefficient ( r 2 , 0.618). To the best of our knowledge, this was the first report for the detection of ethanol using as-grown (at 1000 °C) Gd 2 O 3 nanostructures by simple and reliable I-V technique and rapid assessment of the reaction kinetics (in the order of seconds). The low cost of the starting reagents and the simplicity of the synthetic route made it a promising chemical sensor for the detection of various toxic analytes, which are not environmentally safe.

Highly selective colorimetric detection and preconcentration of Bi(III) ions by dithizone complexes anchored onto mesoporous TiO2

We successfully developed a single-step detection and removal unit for Bi(III) ions based on dithizone (DZ) anchored on mesoporous TiO2 with rapid colorometric response and high selectivity for the first time. [(DZ)3-Bi] complex is easily separated and collected by mesoporous TiO2 as adsorbent and preconcentrator without any color change of the produced complex onto the surface of mesoporous TiO2 (TiO2-[(DZ)3-Bi]) at different Bi(III) concentrations. This is because highly potent mesoporous TiO2 architecture provides proficient channeling or movement of Bi(III) ions for efficient binding of metal ion, and the simultaneous excellent adsorbing nature of mesoporous TiO2 provides an extra plane for the removal of metal ions.