Chemical vapor deposition of a PbSe/CdS/nitrogen-doped TiO2 nanorod array photoelectrode and its band-edge level structure

Lead selenide (PbSe) is a candidate for harvesting infrared (IR) light, due to its narrow and controllable optical band gap which can be tuned by its grain size. However, there is still a challenge to assemble a photoelectrode with different cations of selenide and sulphide sensitizers, such as PbSe and cadmium sulphide (CdS), onto the same skeleton by a wet chemical route. In this work, we provide a chemical vapor deposition (CVD) method to assemble a PbSe and CdS nanoparticle (NP) co-sensitized nitrogen (N)-doped TiO2 nanorod array (PbSe/CdS/NT) photoelectrode. This hybrid photoanode showed an increased photoelectrochemical (PEC) performance under simulated sun light irradiation. Electrochemical analysis revealed that a presumable cascade structure of band-edge levels, in this photoanode, could be attributed to the enhanced photocurrent. In addition, the carrier multiplication in PbSe NPs via impact ionization, was also suggested to contribute to both the photo and dark current.