Photocatalytic water splitting over CeO2/Fe2O3/Ver photocatalysts.

[Display omitted] • Ratio of Fe 2 O 3 and CeO 2 is strongly affecting hydrogen photogeneration. • Determination of Fermi levels is the key to obtain idea of charge transfer. • Efficient Type I heterojunction was confirmed by work function measurements. • The most efficient sample Fe 8 Ce 2 possessed optimal particle distribution. • Photocatalyst anchored on vermiculite is promising due to an easier separation. The study is focused on the photocatalytic ability of nanocrystalline oxides Fe 2 O 3 and CeO 2 (marked as Fe and Ce) and their 8:2, 5:5 and 2:8 M ratio mixtures (marked as Fe 8 Ce 2 , Fe 5 Ce 5 and Fe 2 Ce 8) for the hydrogen production via water splitting. The photocatalysts were prepared using a precipitation procedure both in a "stand-alone" powder form and in form of the Fe 2 O 3 /CeO 2 nanoparticles precipitated on vermiculite (Ver). The phase composition and the specific surface area of the samples, the size and morphology of nanocrystallites of individual phases, and the optical and electronic properties of the photocatalysts were characterized in detail by X-ray powder diffraction, nitrogen physisorption, transmission electron microscopy, diffuse reflectance UV–Vis spectroscopy and work function measurements. Photocatalytic water splitting over the photocatalysts was performed during 8 h in annular batch photoreactor illuminated with 8 W Hg lamp (λ = 254 nm). The most active photocatalysts were Fe 8 Ce 2 both in "stand-alone" powder form and in form of the photocatalyst attached on vermiculite. The photocatalytic generation of hydrogen in the presence of the Fe 2 O 3 /CeO 2 photocatalysts is controlled by the intrinsic photocatalytic properties of the oxides and by the specific surface of the composite. It is enhanced, when heterojunctions between Fe 2 O 3 and CeO 2 form. The work function measurements confirmed the formation of heterojunction Type I with bent bands, which effectively inhibits the recombination of photogenerated charge carriers. In addition, it was confirmed that the anchoring of the photocatalyst on vermiculite does not significantly degrade the photocatalytic activity of the composite. In contrast, even if the amount of the photocatalytically active component was three-times smaller as compared with the photocatalysts without vermiculite, just a slight decrease of the photocatalytic activity was observed. [ABSTRACT FROM AUTHOR]