Síntese e caracterização de compósitos do tipo Cd(1-x)SnO2/(CdS)x e aplicação na geração fotocatalítica de hidrogênio sob ação de luz visível

Abstract

The hydrogen has been considered the energetic vector of the future because of its availability and its flexibility of production and use. A promising and interesting alternative is the generation of hydrogen from the photocatalytic reforming reaction of a glycerol aqueous solution in the presence of a semiconductor under sunlight irradiation. To fully harvest solar energy, composites type Cd(1-x)SnO2/(CdS)x were synthesized by Pechini method followed by ion exchange and heat treatment in nitrogen atmosphere. These composites have demonstrated able to absorb visible light and lead the photocatalytic reforming reaction of glycerol aqueous solution to produce hydrogen. The materials obtained in each step of the synthesis were characterized using different techniques (XRD, Raman, DRS, EDX and SEM). It was possible to investigate the influence of the calcination temperature in the ion exchange step, as well as the cadmium content in the formation of oxides: CdSnO(2-δ) (DT6TN1 and DT6TN3), and of composites CdSnO(2-δ)/CdShex (DT6TN5); CdSnO(2-δ)/CdO/CdShex (DT6TN7); and SnO2/CdO/CdShex (DT6TN9). The composite obtained when calcined at 600 oC and with the same Cd and Sn content in the precursor gel (CdSnO(2-δ)/CdShex) has demonstrated the best photocatalytic activity in hydrogen production, around 290 μmol g-1h-1. This value is very close to the obtained with commercial CdS, but with a great advantage, it has a lower content of cadmium, being less toxic. In this way, composites Cd(1-x)SnO2/(CdS)x were produced that absorb visible light with potential use in the generation of hydrogen from the photocatalytic reforming of aqueous solutions of glycerol.