Study On Synthesis,Modification And Photoelectrochemical Properties Of ?-Fe₂O₃ Nanorod Arrays

Hematite??-Fe₂O₃?has been considered to be a promising material for photoelectrochemical?PEC?water splitting due to its favorable optical band gap,good chemical stability in oxidative environment,abundance,and low cost.However,the performance of PEC water splitting for hematite photoanodes is limited by several key factors such as relatively poor conductivity,a short hole diffusion length?2-4 nm?and slow oxygen evolution reaction?OER?kinetics.Hence,recent studies have focused on improving their PEC activity via various modifications.In this thesis,different modification approaches to enhance the performance of hematite for PEC water splitting are discussed,including element doping,morphology control,the formation of heterojunction and loading of oxygen evolution catalysts?OECs?.The contents are listed as below:?1?Here,we prepare Ti-doped?-Fe₂O₃ nanorod arrays prepared by hydrothermal method with the addition of TiCl₃ as Ti source were used as photoanodes in photoelectrochemical cells.This work examined the influence of the Ti doping level on the morphology and photoelectrochemical properties of hematite photoanodes.Photoelectrochemical impedance spectroscopy shows that photogenerated holes could be transferred from valence band of hematite to electrolyte more efficiently in Ti-doped?-Fe₂O₃ nanorod arrays.The enhancive photoelectrochemical activity of Ti-doped?-Fe₂O₃ nanorod arrays is attributed to the improved donor density and reduced recombination of the electron-hole pairs.The trial results suggest that TF1 photoanode show the potimal photoelectochemical performance and its microstructures is is beneficial to improve charge collection.?2?A successful design and fabrication of novel ternary FeOOH/CdS/Ti-Fe₂O₃ nanorod arrays?NRAs?photoanode is reported aimed at boosting charge-separation and transfer kinetics within the bulk and at the electrode/electrolyte interface.Due to the band alignments of CdS and Ti-Fe₂O₃,the heterostructures can form between CdS and Ti-Fe₂O₃,improving the charge separation efficiency.A facile solution impregnation method is developed for growing ultrathin highly crystalline?-FeOOH nanolayers on CdS/Ti-Fe₂O₃ photoanodes.Fe OOH improve the water oxidation kinetics and reduces the surface charge recombination.It has been found that the synergistic effect of CdS and FeOOH achieves rapid charge transfer kinetics and low positive potential to produce photocurrent,resulting in a highly efficient photoelectrochemical performance.