Effect of temperature on the photosensitized reduction of methyl viologen and hydrogen production by a mixture of zinc phthalocyanine and ruthenium tris-bipyridyl complexes

Abstract

Three aqueous solutions of cetyl trimethyl ammonium bromide (CTAB) at pH 6.5 containing methyl viologen (MV 2+) as an electron acceptor and ethylene diamine tetraacetic acid (EDTA) as an electron donor, were irradiated with visible light. One solution contains zinc phthalocyanine (ZnPc), the second contains ruthenium tris-bipyridyl complex [Ru(bip) 2+ 3], while the third is a mixture of the two in the molar ratio 1:1. Irradiation was carried out at λ = > 650, 460 and 350–700 nm respectively from a 250 W xenon arclamp. Photoreduction efficiency of methyl viologen in the three solutions was higher than that obtained at room temperature [1] and was in the order: ▪ The efficiency of hydrogen production in the two photosensitizers mixture was not affected by a temperature rise as opposed to individual complexes when the three solutions were irradiated with visible light at 45°C in the presence of colloidal platinum (Pt-PVA). A reasonable amount of hydrogen gas was collected after cutting off heat and irradiation.