Study On Structure Modulation And Photoelectrochemical Properties Of TiO₂ Nanorod Arrays

The energy crisis and environmental pollution have seriously affected and hindered the sustainable development of society.Photocatalysis technology has shown great potential for application in renewable energy development and environmental treatment because of its green and economic advantages,and more and more researchers are devoted to the development of high-performance photocatalytic materials.Titanium dioxide（TiO₂）has become a hot research material for photocatalysis because of its high stability and suitable energy band structure.However,the shortcomings of TiO₂,such as narrow photoresponse range and low photogenerated carrier separation efficiency,limit its practical applications.Therefore,structural modulation of TiO₂to expand its photoresponse range and enhance its photogenerated carrier separation efficiency is the main way to achieve its performance optimization.In this thesis,we aim to construct multifunctional TiO₂-based photocatalytic materials and modify TiO₂nanorods by using narrow-bandgap semiconductor compounding,noble metal sensitization,elemental doping and construction of homogeneous heterojunction to improve the utilization of visible light,increase the photogenerated carrier separation efficiency and enhance the photocatalytic,photoelectrochemical and surface-enhanced Raman scattering properties of TiO₂nanorods.The main studies are as follows:（1）TiO₂/Sn S/MoS₂nanorod arrays were prepared on fluorine-doped tin oxide（FTO）conductive glass using a three-step hydrothermal method.The morphology,microstructure,optical properties,photodegradation activity,photoelectrochemical properties and charge transport mechanism of this ternary structure photocatalyst were systematically investigated.The results show that the primary rate constant(0.0122min^-1)of surface TiO₂/Sn S/Mo S₂for rhodamine（Rh B）is about 5.16 times higher than that of TiO₂,and the photocurrent（0.841 m A/cm²）is about 8.32 times higher than that of TiO₂.The excellent photocatalytic and photoelectrochemical properties of TiO₂/Sn S/Mo S₂is mainly attributed to the fact that Sn S and Mo S₂can significantly broaden the photoabsorption rate of TiO₂photoresponsive range,promote the separation of photogenerated carriers,and the Z-type charge transfer mechanism further promotes the transfer of photogenerated charges.（2）TiO₂/Ag/ZIF-8 nanorod array films were prepared on FTO conductive glasses by hydrothermal and in situ synthesis methods.The results showed that TiO₂/Ag/ZIF-8exhibited good photocatalytic and photoelectrochemical properties under visible light irradiation.the photocatalytic rate constant(0.01348 min^-1)and photocurrent density（250.2μA/cm²）of TiO₂/Ag/ZIF-8 for tetracycline were 9.76 times and 5.94 times higher than those of TiO₂,respectively.The excellent photocatalytic and photoelectrochemical performance of TiO₂/Ag/ZIF-8 was attributed to the surface plasmon resonance effect of Ag nanoparticles（NP）that broadened the visible light absorption range,the passivation effect of ZIF-8 that inhibited photogenerated carrier complexation,and the N-Ti-O bond between TiO₂and ZIF-8 that promoted the separation of photogenerated carriers.（3）Multifunctional TiO₂/g-C₃N₄/Ag thin films with excellent surface-enhanced Raman scattering,photocatalytic,and photoelectrochemical properties were prepared on FTO using hydrothermal and in situ synthesis methods.The surface-enhanced Raman scattering enhancement factor of the films can reach 4.94×10⁵,and can detect rhodamine 6G（R6G）molecules down to 10^-12M with good homogeneity.Meanwhile,the TiO₂/g-C₃N₄/Ag has an order kinetic constant of 0.01051 min^-1and a transient photocurrent density of 225.89μA/cm²for R6G,which are 4.07 and 5.87 times higher than those of TiO₂,respectively.more adhesion sites and can enrich more R6G molecules.Second,the significant LSPR effect of Ag NP facilitates the amplification of Raman signals and enhances the SERS performance.Finally,the Z-type heterostructure promotes the photogenerated charge migration,which further enhances its PC and PEC performance.（4）Nitrogen（N）-doped rutile/anatase mixed-phase TiO₂（A-TO（N）@R-TONR）nanorod arrays photoanodes were prepared on FTO conductive glasses using hydrothermal and high-temperature calcination methods.The N-doped improved the utilization of visible light by the photoanodes,and the construction of homogeneous heterojunction promoted the A-TO（N）@R-TONR photogenerated carrier separation,thus significantly enhancing its photoelectrochemical performance.At AM 1.5 G,the photocurrent density of the A-TO（N）@R-TONR photoanode reached 1.94 m A/cm²(V_RHE,1.23 e V).The incident photon electron conversion efficiency reached 81.4%at320 nm,and the surface charge injection efficiency reached 51.6%.Figure[54]Table[6]Reference[133]...