Selectively constructing sandwich-like heterostructure of CdS/PbTiO3/TiO2 to improve visible-light photocatalytic H2 evolution

Fast migration and efficient spatial separation of photogenerated charges in photocatalytic materials are indispensable to efficient solar water splitting reactions. Here, we construct a three-phase heterostructure of CdS/PbTiO3/TiO2 by selectively depositing CdS and TiO2 at oppositely poled crystal facets of PbTiO3 using single-domain ferroelectric PbTiO3. The heterostructure has matching band edge alignments and strong interfacial connections at different moieties. The heterostructure combines the interfacial electrical and ferroelectric fields because of their peculiar microstructures, which provide a strong driving force throughout the whole bulk to separate photogenerated charges. Almost two orders of magnitude improvement of visible-light-driven photocatalytic H2 production has been realized in CdS/PbTiO3/TiO2 compared with bare PbTiO3/TiO2, showing the efficiency of charge separation in the heterostructure. The idea of combining ferroelectrics with potential light capture semiconductor provides a paradigm to accurately design charge migration pathways, bringing a step closer to efficient solar water splitting.