Photocatalytic transformation of rhodamine B and its effect on hydrogen evolution over Pt/TiO2 in the presence of electron donors

In the presence of electron donors, oxalic acid, ethanol and disodium ethytene-diamine tetraacetate (EDTA), the photocatalytic transformation of rhodamine B (Rh B) and its effect on photocatalytic hydrogen evolution over PL/TiO2 have been examined. UV-Vis and fast atom bombardment mass spectrometry (FABMS) evidences demonstrate that two reductive reaction paths (photocatalytic hydrogenation and additive combination of Rh B with ethanol radical) take place over Pt/TiO2 in the reaction system. The adsorption behavior of Rh B oil Pt/TiO2 with coexisting electron donors is a key factor for the transformation. As a result of the hydrogenation and the addition of ethanol radical, the rates of photocatalytic hydrogen generation by the donors decrease notably. A possible reaction mechanism is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.