Investigation on the influence of pH on structure and photoelectrochemical properties of CdSe electrolytically deposited into TiO_2 nanotube arrays

摘要

In this work, we fabricated CdSe/TiO_2 nanotube arrays (NTAs) by electrochemicai method. In electrode-position, the pH value of the electrolyte played an important role in formation of CdSe nanoparticles. As the pH value decreased, more CdSe deposited on TiO_2 NTAs. Scanning electron microscopy and transmission electron microscopy characterization shows that the CdSe nanoparticles were uniformly deposited on and into TiO_2 nanotubes when the pH value was 3, and this structure fully utilized the three-dimensional (3D) space of TiO_2 nanotubes to form 3D multijunction heterostructures. According to the photo-electrochemical test, the CdSe/TiO_2 NTAs sample prepared at pH = 3 exhibited maximum photocurrent and open circuit potential. This is because that the deposited CdSe nanoparticles had better bond with the walls of TiO_2 nanotube than the samples deposited at other pH values, which facilitated the propagation and kinetic separation of photogenerated charges.