Preparação e caracterização de filmes finos automontados de polieletrólitos/TiO2/CdSe para aplicação na geração de hidrogênio a partir da fotocatálise da água

Abstract

The self-assembled films (SAF) by physical adsorption, compounds of organic polyelectrolytes and inorganic semiconductor nanoparticles are considered an inexpensive process and non-pollutant deposition that gives films with high molecular organization. The aim of this work was to fabricate and characterize SAF via the layerby- layer technique (LbL) and evaluate the potential application of these systems to produce hydrogen (H2) by water splitting technique by solar radiation. In this work were deposited three different sets of films. The cationic system and the number of deposited layers (40) are common to all three types of SAF. The system was composed by the cationic aqueous solution of polycation polyallylamine hydrochloride (PAH), and colloidal inorganic semiconductor cadmium selenide (CdSe). The anionic systems were comprised of aqueous solutions of organic polyanions poly(acrylic acid) (PAA) and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) and colloidal photoactive semiconductor titanium oxide (TiO2 P25 and TiO2 STS-100). Analysis of SAF by profilometry revealed that the thickness of the self-assembled films are of nanometer order; by diffuse reflectance spectrum observed absorption bands in the near ultraviolet region and the visible region and through the chromatography was given the average H2 production. The system with the highest value of H2 production rate - (PAH + CdSe) / (PEDOT: PSS + TiO2 STS-100) - was optimized at 120 layers. In the evaluation of the contribution of the type semiconductor nanoparticle for the generation of H2 results chromatography indicated that the combination of (CdSe + TiO2 STS-100) promotes an increase of 75% from this generation as compared to SAF only composed by the semiconductor TiO2 STS -100.