Study On Preparation And Properties Of Iron-based Oxide Thin Film Photoanodes

The production of H₂ fuel from abundant solar energy through photoelectrochemical（PEC）water splitting is considered to be an attractive method to solve serious energy and environmental problems.However,in practical applications,semiconductor materials that can be used for photoelectrochemical water splitting will face many problems and challenges.The biggest problem is how to construct a photoanode material that has both efficient charge carrier separation and transport and fast surface reaction kinetics.Among many materials, iron-based oxide materials are favored by researchers due to their abundant sources,suitable band gap size,non-toxicity and low cost.However,due to the inherent limitations of iron-based oxide materials,such as low conductivity,fast recombination rate of charge carriers at the bulk or surface,and slow reaction kinetics.Therefore,aiming at the serious charge recombination problem of iron-based oxide films,a modification study is proposed through element doping and surface modification.Furthermore,studying the performance improvement to provide theoretical and experimental basis for design and preparation of high-efficiency photoanode materials.The main research contents and results are as follows:（1）By comparing the effects of different doping methods of Ti ions on the properties ofα-Fe₂O₃ films,it is revealed that the dopedα-Fe₂O₃ film from low to high concentrations（2%-4%）has better PEC performance.Further,PEDOT（3,4-ethylenedioxythiophene monomer polymer）:PSS（polystyrene sulfonate）hole conductive polymer is used for surface modification.This reveals that PEDOT can not only inhibit the surface recombination of photogenerated electrons and holes,but also accelerate the transparent of surface charge.（2）Argon post-annealing introduces oxygen vacancies in the BiFeO₃ film to improve the charge carrier density and charge separation efficiency.Further,surface modification is performed by PEDOT to suppress the accumulation and recombination of carriers at the the surface defect,thereby improving the water splitting performance.In addition,by applying an electric field to make BiFeO₃ spontaneously polarized,we propose and verify that PEDOT will not affect the positive effects of its polarization.