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Películas delgadas de TiO2, CZTS y TIO2/CZTS fueron preparadas mediante técnicas de sol gel y evaporación térmica. Las películas obtenidas fueron caracterizadas estructural, óptica y morfológicamente. Los resultados muestran la presencia de anatasa y kesterita, así como fases secundarias de CuS y Sn,S3. ópticamente, las películas de TIO ) muestran absorción en la región UV entre 300 nm y 350 nm, mientras que las películas modificadas con CZTS presentan absorción en el intervalo de 500-700 nm, correspondiente a la región visible. La morfología de las películas de TIO//CZTS muestra tamaños de partículas homogéneos y una distribución uniforme. Los resultados de la evaluación fotocatalítica muestran un 90% de degradación de fenol en presencia de las películas de TiO¿/CZTS, lo cual es superior a los resultados mostrados por las películas de TiO, y CZTS por separado.

Anatase TiO2 and TiO2 films containing Pt nanoparticles were prepared by sol–gel dip coating method and characterized by X-ray diffraction (XRD), atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Further, optoelectronic properties were investigated, showing that for anatase TiO2 films containing Pt nanoparticles there were not changes in the band-gap value in respect to TiO2 films here obtained. However, an increase in the photoresponse and a decrease in resistivity with increase in the Pt % weight (% w) in sol were found. Keywords: TiO2 films, Solar energy, Nanoparticles

This work shows the results obtained in the synthesis of srilankite nanoparticles, (Zr, Ti)O2, and TiO2 anatase, both catalysts presented an admix of phases, anatase/rutile, and srilankite/rutile, respectively. Their performance in the production of biodiesel through the esterification of oleic acid was evaluated. The catalysts were obtained using the sol-gel process and sulfated via the impregnation method. The samples were characterized using X-ray diffraction (XRD), scan electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier-Transform Infrared Spectroscopy (FTIR) to analyze the properties in its crystalline structure, morphology, and chemical composition. Its efficiency during the esterification reaction was measured based on the decrease in free fatty acids (FFA). FFA, oleic acid was added at different weight percentages (1%, 3%, and 5% w/w). The time of reaction was 6 hours at 55 °C and the catalyst with better performance was the sulfated Srilankite/rutile, reaching a maximum conversion of up to 90%.

Admix of Cu2ZnSnS4 (CZTS) and ZnS phases in thin films were prepared on glass substrate by thermal evaporation from CuS, ZnS and SnS as precursors. Their composition, microstructure and optical properties of thin films were determine using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Vis absorption. The conglomerate grain shape of the obtained materialare elongated with dense morphology. Kesterite structure was obtained after heat treatment at 400 °C of precursors. By Rietveld refinement method was determined the presence of CZTS phase and ZnS phase at 65% and at 35%, respectively. By elemental analysis, it was notice Cu loss in the heating process. Band gap value of the resulting material was 1.49 eV. Regarding to the optoelectronic properties for make solar cells, this film shows good photoconductivity.

In this work, the corrosion evaluation of a double black layer, by an acidic bath of double electroless Ni-P coatings, were conducted. A double black layer and a coarse sandblast finishing were intended for increasing the sunlight absorption and its anchoring. The surface preparation process comprises four stages: A) a Ni-P electroless coating, B) an acidic attack for a black layer formation, C) a second Ni-P electroless coating, and D) an acidic attack for a second black layer. The properties of the coating were investigated by X-ray diffraction, scanning electron microscopy, mechanical profilometry, confocal laser scanning microscopy and low-discharge optical emission spectroscopy. The results of these studies indicate that a double layer Ni-P coating with Rp and corrosion rate values of 1170 Ω cm2 and 0.4 mm/year were obtained, thereby exhibiting an increase in corrosion resistance compared to a one layer Ni-P coating. The GDOES profiles show two Ni-P coatings and two black layers intercalated through small variations of the percentage of nickel and phosphorus, which was associated with the interface between both layers.

The photochromism of poly methyl methacrylate–TiO2 composites have been investigated in this research. Amorphous titanium oxide was synthesized by sol–gel using titanium isopropoxide. The titanium solution was mixed with a dissolved polymer. The composite shows photo-response under UV radiation by changing, generally, to a dark brown tonality. This effect was reversible in different time ranges according to the intensity and exposure time. The mechanism for this photochromic change was proposed as a reduction of TiOOH domains to Ti3+ and not directly from amorphous TiO2, which provide electron-hole pairs after absorbing UV. The backscattered electrons image shows the clusters or domains of titanium compounds as white dots, ranging from 0.1 to 1 μm. The electron spin resonance spectroscopy signals indicated a titanium valence change from Ti(IV) to Ti(III). The X-ray photoelectron spectroscopy peaks positions for Ti 2p1/2 and Ti 2p3/2 were assigned as Ti4+. The values were obtained for Ti 2p3/2 and the identified species were Ti4+ and Ti3+, that correspond to TiO2, Ti2O3, and Ti(OOH). Few and small crystalline domains were identified by Transmission Electron Microscope as orthorhombic TiO2.’

The scope of the chapter is showing novel experimental findings on preparing anatase TiO2 nanoparticles, first anodizing titanium into an organic media for obtaining TiO2 nanotubes, and these used as a photo catalytic active electrode in treating water polluted with organic contaminants. The substrates were grit blasted in order to obtain mechanical fixation of the generated nanotubular TiO2 structure. This was successfully achieved without diminishment of the nanotubes order and with a self-leveling of the outer surface. A new phenomenon is investigated consisting in the process of oxidation of the nanotubes in water after anodizing. Along this process, methyl orange added to the aqueous solution was discolored as part of the redox reaction involved. The final state of the modified layer was composed of conglomerates of crystalline TiO2 nanoparticles, around 4 nm in size, consisting of anatase. This was obtained under room conditions.

This chapter shows the experimental findings on preparing TiO2 nanotubes by anodizing titanium into an organic medium for an intended use as a fotocatalytic active electrode in treating water polluted with organic contaminants. The substrates were grit blasted in order to obtain mechanical fixation of the generated nanotubular TiO2 structure. This was successfully achieved without diminishment of the nanotubes order and with a self-leveled outer surface. A new phenomenon occurred when detached fragments from the modified layer were electrophoretically deposited. They were ordered and grow as deposits. In addition, they maintain their nanotubular shape conferring a homogeneous size in the porous structure.