Preparation And Photoelectric Properties Of BaTiO₃/CdS And TiO₂/BaTiO₃ Heterojunction Micro-nano Structures

High PEC water-split efficiency based on high-performance semiconductor photoelectric materials.Among many semiconductor photoelectric materials,BaTiO3(BTO),a ferroelectric material,has attracted wide attention of scientists,because its spontaneous polarization field can promote the effective separation and transfer of photocarriers.However,the wide band gap makes BTO can't absorb visible light well.Therefore,in this paper,BTO is coupled with narrow band gap of CdS to form a heterostructure to broaden its light response range,that could improve its photoelectrochemical performance.On the other side,using the ferroelectricity of BTO,the TiO2/BTO heterojunction micro-nano structure was constructed by coupling it with the traditional photoelectric electrode material of TiO2,to study its photoelectrochemical performance influence by shell thickness of the ferroelectric BTO grow on TiO2.The main research contents and results of this paper were summarized as follows:(1)Using TiO2 nanowire array as the precursor and Ba(OH)2·8H2O as the source,we synthesized BTO at different Ba2+ concentration and different temperature by two-step hydrothermal method.Through a series of tests,the results show that the pristine BTO nano array with tetragonal phase can be successfully synthesized at the reaction temperature of 210? with 0.06 M Ba(OH)2·8H2O.Compared with the precursor TiO2,BTO has faster photocurrent response speed and better photoelectric performance.The photocurrent density of BTO is 4.5 times of TiO2 under simulated sunlight.(2)Using Cd(NO3)2·4H2O as Cd source,and Na2S·9H2O as S source,BTO/CdS heterojunction micro-nano structure was successfully constructed by successive ionic layer adsorption and reaction method(SILAR)on FTO grass at different number of SILAR cycles.The result shows:Compared with BTO substrate,the light response range of BTO/CdS is broadened from ultraviolet to visible,and the photocurrent density of BTO/CdS-15 heterostructure can reach 1.8 mA/cm2,which is 7.8 times of BTO substrate.The wide optical absorption range and ferroelectricity of BTO promote the effective separation and transfer of photocarriers,which can greatly improve the photoelectric performance.(3)TiO2/BTO heterostructures with different thickness of BTO shell were fabricated by solvothermal method at different temperature.The results show that when the reaction temperature is below 150?,the morphology of TiO2/BTO heterojunction micro-nano structure keeps the same rod structure as the pristine TiO2 With the increase of temperature,the photocurrent density of TiO2/BTO-160 heterojunction is 20 times of pristine TiO2 and 4 times of BTO substrate.The heterojunction structure and the spontaneous polarization field of BTO exist,can promote photocarrers separate and transfer,the photoelectric performance of TiO2/BTO heterojunction micro-nano structure has been significantly enhanced.