VISIBLE-LIGHT INDUCED HYDROGEN-PRODUCTION WITH CU(II)/BI2O3 AND PT/BI2O3/RUO2 FROM AQUEOUS METHYL VIOLOGEN SOLUTION

Gamma-Bi2O3, a rarely studied oxide semiconductor, was doped individually with Cu(II) in different concentrations, Pt and RuO2 (0.5 wt%) and used as a fine powder for photocatalytic production of hydrogen from water in the presence of methyl viologen (MV2+) as an electron relay. The diffuse absorption spectroscopy of the samples revealed that the doping process improved the absorption of gamma-Bi2O3 in the visible region while the XRD spectra indicated no change in crystal structure, but an enhancement in crystallinity. For 90 min irradiation (lambda greater-than-or-equal-to 400 nm) of the aqueous slurry of the catalyst in presence of MV2+, 0.79 and 0.66 ml of hydrogen were generated by 4 at% Cu(II)/Bi2O3 and Pt/Bi2O3/RuO2 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.