Hydrogen evolution by photocatalytic decomposition of water under ultraviolet–visible irradiation over K2La2Ti3−xMxO10+δ perovskite

New layered transition metal substituted perovskite-type oxides K2La2Ti3−xMxO10+δ (M = Fe, Ni, W; δ varies with different M) were synthesized with high-temperature solid state reaction, and characterized with X-ray diffraction (XRD) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). The photocatalytic activity of these catalysts was studied under ultraviolet and visible light irradiation. The results indicated that substitution of a part of Ti4+ with Fe3+ and W6+ resulted in a marked increase in water splitting activity. The activity of these catalysts for water splitting decreased in the order: Fe3+ > W6+ > Ni2+ ≥ no substitution. The effect of different amounts of Ti4+ with Fe3+ substitution on water splitting was also evaluated. The highest hydrogen evolution was observed for perovskite composition having a Fe:Ti molar ratio of 1:14 (1:12 weight ratio) and this hydrogen evolution was over 4 times higher than the Fe-free K2La2Ti3O10 composition. Fe was also found to be a promising component for photo activity under visible light irradiation. Finally, the effect of Na2S/Na2SO3 system as the sacrificial agent on the photocatalytic activity was also studied.