Vertically aligned ZnO nanorods/CdS nanowires branched heterostructures: Cathodoluminescence properties and photovoltaic application

• ZnO nanorod arrays were fabricated on FTO glass using a hydrothermal growth.
• CdS nanowires branches were decorated with ZnO by vapor–liquid–solid approach.
• Luminescence quenching showed type II band alignment between CdS and ZnO
• 1.15% efficiency was obtained for photoelectrochemical cell devices.
• We demonstrated the passivation of recombination sites by a thin layer of Al2O3.

Hierarchical type-II heterostructures were fabricated on FTO glass based on vertically aligned ZnO nanorod arrays (NRAs) decorated with CdS nanowires (NWs) branches using a sequential hydrothermal growth (ZnO NRAs), vapor–liquid–solid approach (CdS NWs). The cathodoluminescence (CL) properties of the fabricated ZnO/CdS heterostructure demonstrated the good quality of the material as well as luminescence quenching thus suggesting type II band alignment between CdS and ZnO. Photoelectrochemical cells were fabricated with an effective electrode area ∼0.2 cm2 resulting in 0.65 V VOC and 1.15% efficiency for devices based on ZnO NRAs/CdS NWs heterostructures using a thin layer (∼2 nm) of Al2O3 at the interface between ZnO nanorods and CdS branches.