The Synthesis And Modification Of TiO₂and ZnO Nanorod Arrays And The Study On Their Photoelectrochemical Property

In this thesis, we utilized simple hydrothermal method to achieve the epitaxialgrowth of TiO2and ZnO nanorod array photoelectrodes on FTO glass and theirmorphology and ratio of length to diameter were optimized by searching suitablesynthesis conditions. On this basis，we considered the fact that both TiO2and ZnO arewide gap semiconductors (band gap over3eV) and they can only absorb ultravioletlight. However, most of the solar energy is distributed into visible light. In this thesis,we enhanced the phoelectrochemical performance of the photoelectrodes byimproving their visible light absorption. We used glucose as carbon source to modifythe TiO2nanorod by carbon doping. Although obvious red shift phenomenon was notappear in the UV-vis spectrum, the photocurrent vs voltage (I-V) results achievedunder standard light intensity showed increased photocurrent after modification.X-ray powder diffraction (XRD) results showed the TiO2examples are rutile TiO2andthe crystal phase did not change after a low concentration of carbon doping. Scanningelectron microscope (SEM) showed that the TiO2nanorod shows cuboid shape, about1 m in length and100nm in width. For the modification of ZnO nanorod, we chosethiourea as the sulfur source and the ethanediamine (forming complex with Cd2+ions)was used to control the simple hydrothermal reaction process of depositing CdS andZnxCd1-xS on ZnO. As is shown in the UV-vis results, the deposition of CdS andZnxCd1-xS makes the light absorption of the photoelectrodes changed from about380nm to510nm. The SEM results of the photoelectrodes obtained from differentethanediamine to cadmium nitrate mole ratio condition show their morphologychanges from nanorod to nanoflower and nanosphere. We also investigated thecrystallization results of the samples by XRD. Finally, the photoelectrochemicalproperty of the photoelectrode was characterized under the standard simulated solarlight by three-electrode electrochemical workstation to obtain the I-V curves. Theoptimized photoelectrode was obtained after a series of experiments.