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.