Enhanced photoelectrochemical performance of CdSe sensitized Al-doped ZnO photoanode compared with CdSe-ZnO

CdSe nanoparticles sensitized Al-doped ZnO nanorod array films (CdSe–AZO) were prepared via a simple two-step method. The morphological, structural, optical and photoelectrochemical (PEC) properties of the films have been examined. The results confirm that Al element has been implanted into the ZnO lattice structure and distributed in the ZnO nanorod homogenously. CdSe nanoparticles were deposited on Al-doped ZnO nanorod, and the heterojunction interfacial structure of CdSe/AZO was verified by high resolution transmission electron microscopy. The photoresponse of Al-doped ZnO nanorod array films in the visible region has been significantly improved by sensitizing them with CdSe nanoparticles. Under AM 1.5G illumination, the CdSe–AZO electrode have an optimum short-circuit photocurrent density of 4.28mAcm−2, nearly 13 times of bare ZnO and 1.7 times of CdSe–ZnO. We attribute the improvement to the fact that Al doping augments more active centers and then increases the amount of CdSe nanoparticles grown on AZO, which leads to significantly enhanced optical absorption and more efficient charge transfer channel. This study provides an insight of combination inorganic semiconductor sensitization with elemental doping for improving PEC properties.