Preparation Of Fe 2 O 3 Modified Electrode And Its Photoelectrochemical Performance

In recent years,consumption of the fossil energy such as petroleum and coal increases sharply with the rapid growth of the social economy,the world faces a serious energy crisis.Hydrogen is a kind of green energy,and has got more and more attentions.Since it was found that hydrogen can be obtained by photosplitting of water using TiO2,hydrogen production through photoelectrochemical water splitting on various semiconductors has been widely studied.Fe₂O₃,due to its high chemical stability,visible-light activity,low cost and easy availability,has been regarded as one of most promising photoanode materials for solar hydrogen production in practice,The preparation and development of high photo-active Fe₂O₃ or Fe₂O₃-based photoelectrode materials for photoelectrochemical hydrogen production is a hot topic at present.This work deals mainly with the preparation and photoelectrochemical study on both bareα-Fe₂O₃ and V-,Cu-,or Ni-modified α-Fe₂O₃ materials,The results of this work show that the surface-modification of Fe₂O₃ is an effective method for improving its photoelectrochemical activity for water photolysis.α-Fe₂O₃ electrode material was prepared following a procedure of hydrolyzation,coating and annealing.Firstly,ferric chloride saturated solution were dropped into the boiled distilled water to prepare the iron hydroxide sol.Then,the prepared iron hydroxide sol was coated onto a titanium or platinum substrate.Thirdly,the samples were annealed in a muffle furnace at 450 ℃,500 ℃ and 550 ℃,roast for 1.5 h to achieve the conversion from iron hydroxide to α-Fe₂O₃.It was found that the electrode annealed at at 550 ℃ exhibited best photoelectrochemical performance.Surface-modified Fe₂O₃ electrodes were prepared firstly by dipping and heat treatment.Modification solutions were 0.1 M VOSO₄,Cu（NO₃）₂,and Ni（NO₃）₂ solutions,respectively.After dipping Fe₂O₃ electrode in the modification solutions either at room temperature or at90 ℃ for 1 h,the samples were anealed again at 550 ℃ for 1.5 h.Photoelectrochemical measurements showed that,while the surface modification was favorable for improving the photoactivity for water splitting,the measured photocurrents of the surface-modified Fe₂O₃ electrodes prepared at 90 ℃ were higher than those prepared at room temperature.Moreover,it was found that for the three surface-modified Fe₂O₃ electrodes prepared by dipping in 90 ℃ modification solutions,the V-modified Fe₂O₃ electrode showed best photoelectrochemical performance,which was reflected by its photocurrents about 1.5 timeshigher than that of nickel-modified Fe₂O₃ electrode,and about 3 times higher than that of copper-modified Fe₂O₃ electrode.It was concluded that the best modification scheme is the modification at 90 ℃ in 0.1 M VOSO₄ solution.