A systematic comparative study of the efficient co-catalyst-free photocatalytic hydrogen evolution by transition metal oxide nanofibers

The efficiencies of a series of hydrogen evolving catalysts based on metal oxide nanofibers (NiO, Co₃O₄, Mn₃O₄) are investigated for the photocatalytic hydrogen evolution from water without using any co-catalyst under the visible light irradiation by using triethanolamine (TEOA) as an electron donor and Eosin-Y (EY) dye as a photosensitizer. It is found that the photocatalytic hydrogen evolution activities follow the order as: Mn₃O₄3O₄?1h^?1, 5552 μmolg^?1h^?1, 7757 μmolg^?1h^?1, respectively). Moreover, the catalytic behavior of these nanofibers on the hydrogen production has been also compared to bulk forms of NiO, Co₃O₄ and Mn₃O₄ by producing hydrogen 937 μmolg^?1h^?1, 901 μmolg^?1h^?1 and 135 μmolg^?1h^?1, respectively. The nanofiber structures demonstrated much higher photocatalytic activity than bulk forms due to the effect of the increased surface to volume ratio deduced from the fibrous character. The photocatalytic plausible pathway for the hydrogen production is also discussed.