PbSe nanocrystal/TiO_x heterostructured films: A simple route to nanoscale heterointerfaces and photocatalysis

A simple approach to heterostructured thin film catalysts consisting of PbSe nanocrystals and layer-by-layer deposited TiO_x is presented. Strong quantum confinement raises the conduction band of PbSe nanocrystals above that of TiO_x, leading to a type II band offset. Photogenerated electrons in PbSe nanocrystals are transferred to catalytic TiO_x which in turn initiate catalysis. Photocatalytic activity of the heterostructured films is found to be dependent on the size of the PbSe nanocrystals with the onset of catalysis coinciding at a photon energy of ∼2.5 times the band gap of the nanocrystals. Photocatalysis in the visible spectral region out to 650 nm is demonstrated.