Highly efficient visible-light driven photocatalytic hydrogen production from a novel Z-scheme Er3+:YAlO3/Ta2O5-V5+∥Fe3+-TiO2/Au coated composite

In this work, the preparation of a novel Z-scheme photocatalyst, Er3+:YAlO3/Ta2O5-V5+parallel to Fe3+-TiO2/Au coated composite, for visible-light photocatalytic hydrogen production is reported for the first time. In this photo catalyst, Au nanoparticles as conduction band co-catalyst provide more active sites to enrich electrons. Ta2O5-V5+parallel to Fe3+-TiO2 as composite redox cycle system thoroughly separates the photo-generated electrons and holes. In addition, Er3+ :YALO(3) as up-conversion luminescence agent (from visible-light to ultraviolet-light) provides enough ultraviolet-light for satisfying the energy demand of wide band-gap semiconductors (TiO2 and Ta2O5). The photocatalytic hydrogen production can be achieved from methanol as sacrificial agent (electron donor) under visible-light irradiation. The main influence factors such as initial solution pH and molar ratio of TiO2 and Ta2O5 on visible-light photocatalytic hydrogen production activity of Er3+:YALO(3)/Ta2O5-V5+ parallel to Fe3+-TiO2/Au coated composite are discussed in detail. The results show that the Er3+:YALO(3)/Ta2O5-V5+parallel to Fe3+-TiO2/Au coated composite with 1.0:0.5 M ratio of TiO2 and Ta2O5 in methanol aqueous solution at pH = 6.50 displays the highest photocatalytic hydrogen production activity. Furthermore, a high level of photocatalytic activity can be still maintained within three cycles under the same conditions. It implies that the prepared Z-scheme Er3+:YALO(3)/Ta2O5-V5+ parallel to Fe3+-TiO2/Au coated composite may be a promising photocatalyst utilizing solar energy for hydrogen production.