Visible light induced hydrogen production with Cu(II)/Bi2O3 and Pt/Bi2O3/RuO2 from aqueous methyl viologen solution

Abstract

Abstract γ-Bi 2 O 3 , a rarely studied oxide semiconductor, was doped individually with Cu(II) in different concentrations, Pt and RuO 2 (0.5 wt%) and used as a fine powder for photocatalytic production of hydrogen from water in the presence of methyl viologen (MV 2+ ) as an electron relay. The diffuse absorption spectroscopy of the samples revealed that the doping process improved the absorption of γ-Bi 2 O 3 in the visible region while the XRD spectra indicated no change in crystal structure, but an enhancement in crystallinity. For 90 min irradiation ( λ ≥ 400 nm) of the aqueous slurry of the catalyst in presence of MV 2+ , 0.79 and 0.66 ml of hydrogen were generated by 4 at% Cu(II)/Bi 2 O 3 and Pt/Bi 2 O 3 /RuO 2 respectively. A suitable mechanism involving the reactions of photogenerated e − and h + has been proposed for the photodecomposition of water. The effects of dopant concentration and the catalyst amount on hydrogen production have also been explained.