Abstract

MILLS, A.  and  VALENZUELA, M.A.. Photo-oxidation of water sensitized by TiO₂ and WO₃ in presence of different electron acceptors. Rev. mex. fis. [online]. 2004, vol.50, n.3, pp.287-296. ISSN 0035-001X.

The photo-oxidation of water is studied in presence of UV-light (λ < 400 nm) using titanium dioxide (TiO₂) and tungsten oxide (WO₃,micro-and nano-crystalline) semiconductors in presence of different sacrificial electron acceptors (SEA): Fe(NO₃)₂, Na₂S₂O₈, Ce(SO₄)₂, Co[(NH₃)5Cl]Cl₂, AgNO₃, HgCl₂ and Cu(NO₃)₂. TiO₂ is 5 to 10 times more photoactive than WO₃ with reference to oxygen evolution. Ag ions are the best of the SEAs, for all the semiconductors tested in the photo-redox process. No oxygen evolution is observed when Hg²+ or Cu²+ ions are used as SEAs. The effect of high (10^-2 mol dm^-3) and low (10^-3 mol dm^-3) SEA concentrations is also studied but no common trend is observed. Instead, each system (i.e., SEA+H₂O+Semiconductor) exhibits a different behaviour and the results are rationalised in terms of the spectral and redox potential features of the system.

Keywords : Semiconductor photosynthesis; TiO₂; WO₃; water oxidation; electron acceptor.