Alginate as Template in the Preparation of Active Titania Photocatalysts

Autores UPV
Año
Revista ChemCatChem

Abstract

¿ A simple and reliable procedure to prep. TiO2 and Au/TiO2 samples with high photocatalytic activity for hydrogen generation from water/methanol mixts. is reported, which uses natural alginate as the templating agent. Aq. solns. of sodium alginate are flocculated as beads by Ti-O2+ ions in the presence or absence of AuCl4-. The resulting alginate beads contg. approx. 25 wt % of Ti and various Au contents are dehydrated by ethanol washings before drying under supercrit. CO2 conditions. The key step in the prepn. method is to obtain Au/Ti-contg. alginate aerogels of approx. 700 m2 g-1 Brunauer-Emmett-Teller surface area. The surface area of the TiO2 and Au/TiO2 samples obtained after calcination of the org. biopolymer at 450° C under air ranges from 187 to 136 m2 g-1, and the Au content has been varied from 1.3 to 0.05 wt % to optimize the photocatalytic activity of the samples. TiO2 forms in the anatase phase according to XRD and Raman spectroscopy. The highest activity Au/TiO2 sample (contg. 0.556 wt % of Au) prepd. by means of the biopolymer templating method was approx. eight times more active for hydrogen generation using a solar simulator than was an analogous Au-contg. TiO2 P25 sample prepd. by means of the conventional deposition-pptn. method.