Photocatalytic H2 production from glycerol aqueous solutions over fluorinated Pt-TiO2 with high {001} facet exposure

An optimized fluorinated TiO2 catalyst with high {001} facet exposure loaded with platinum (TiO2-PtFAC) was tested in the photocatalytic hydrogen production from glycerol solution under UV light irradiation. The samples were synthesized by direct hydrothermal treatment starting from two different types of precursors that are titanium tetraisopropoxide (I) or titanium butoxide (B), while platinisation was performed by photodeposition method. The obtained catalysts were characterised by different techniques (XRD, FESEM, TEM, BET, UV-vis DRS, XRF and XPS) and the results evidenced that anatase is the only crystalline phase present in all TiO2 samples. The morphology of the samples was seen as rectangular platelets particles where Pt particles were was observed all over the surface. The presence of Pt and F in the platinised samples was also confirmed by XRF and XPS analysis. The photocatalytic results have shown that the presence of Pt on TiO2{001}facet surface remarkably enhanced the hydrogen production from aqueous solution at 5 wt % of glycerol. Comparing the results obtained from the photocatalysts prepared by the two different precursors, it was found that the best performances in terms of H-2 production was achieved with TiO2-PtFAC(I) (about 13 mmol L-1 after 4 h of irradiation time), while the H-2 production was lower for TiO2-PtFAC(B) (about 9 mmol L-1 after 4 h of irradiation time). The effect of the operating conditions using TiO2-PtFAC(I) evidenced that the highest H-2 production was obtained with a photocatalyst dosage equal to 1.5 g L-1, initial glycerol concentration at 5 wt% and a pH value equal to 7. Finally, a photocatalytic test was also performed on glycerol solution prepared with a real water matrix. Despite the presence of ions scavengers (chlorides and carbonates) in solution, TiO2-PtFAC(I) was able to reach a photocatalytic H-2 production of about 6 mmol L-1 after 4 h of UV light irradiation.