The Synthesis Of Two-dimension TiO₂ Heterostructures And The Investigation On Theirs Photocatalytic Performance

Among many semiconductor materials,titanium dioxide(TiO2)has been widely used in environmental and energy application,et al.because of the low cost,strong redox ability,environmental friendliness,high catalytic activity,and relatively stable chemical properties,and plays an important part in water decomposition,CO2 reduction and organic pollutants degradation.Among many morphologies and structures of TiO2,two-dimensional TiO2 has the advantages of larger specific surface area,more active sites,which has been extensive attracted attention.However,the wide band gap and high recombination rate limit the application of TiO2 in photocatalysis.There are many methods for doping and modification of TiO2,including precious metals deposition,semiconductor compound,and metal ion doping,etc.Among them,semiconductor compound can form a variety of charge transfer mechanisms,then promote the separation of photogenerated carriers,and improve the spectral response of TiO2.In this thesis,two-dimensional TiO2 was prepared and its photocatalytic performance was studied systematically.The main research contents are as follows:(1)The Growth mechanism of Two-dimensional TiO2 nanosheets and the Investigation on its Photocatalytic activity:Two-dimensional TiO2 nanosheets were synthesized on FTO conductive glass(SnO2:F)with ammonium hexafluorotitanate and tetrabutyl titanate by one-step hydrothermal method.The effects of different hydrothermal reaction time(3h-6h-9h-12h-16h)on the structure,morphology and photocatalytic activity of TiO2 nanosheets were studied.The results show that the sample with 12h growth time exhibited the best photocatalytic performance,which is mainly attributed to the uniform morphology of anatase TiO2 nanosheet after 12h hydrothermal reaction,and own a relatively large specific surface area.And more exposed proportion of {101} crystal planes,which is of great significance for the greater photocatalytic activity to RhB solution.(2)The Synthesis of TiO2/SnS2 nanomaterials and the Investigation on its Photocatalytic Performance:The two-dimensional TiO2/SnS2 nanocomposite structure was synthesized by a two-step hydrothermal method.The research results show that the two-dimensional TiO2/SnS2 nanocomposite structure extended the spectral response to the visible light range and increased the separation efficiency of the photo generated carriers.The nanocomposite materials efficiently degraded common organic dyes such as methyl orange(MO),methylene blue(MB),tetracycline antibiotics(TCs),rhodamine(RhB)and so on.And when the molar ratio of Sn:Ti is 0.15:1,TiO2/SnS2 composite structure exhibited the best photocatalytic performance and photoelectric conversion performance.This is mainly attributed to three aspects:(1)narrow-band gap semiconductor composite,which is conducive to expand the range of spectral response;(2)face-to-face two-dimension nanostructures,which provide channels for the transfer of photo-generated charges;(3)Z-type heterojunction charge transfer mechanism improved the separation efficiency of photogenerated charges.