| In recent years,the energy crisis and environmental pollution have become increasingly urgent.People have great expectations for the development and application of renewable energy.The design and use of semiconductor devices to convert clean solar energy into electricity and hydrogen can be the breakthrough in solving energy and environmental problems.Titanium dioxide(TiO2),as wide band gap semiconductor,has the advantages of cheap,non-toxic,stable chemical properties and high photocatalytic activity.It is widely applied in energy,environment and biological fields.The TiO2 nanorod array with one-dimensional structure,compared with the traditional TiO2 nanoparticles,has gained wide attention in terms of specific surface area,electron transport and recycling.On the basis of one-dimensional TiO2 nanorods,the nano-heterostructure can be constructed,which can significantly enhance the absorption of sunlight by TiI2 and improve its photoelectric chemical properties.In this article,the highly ordered TiI2 nanorods array were synthesized on the fluorine doped tin oxide(FTO)conductive substrate by the traditional hydrothermal method.The heterostructures on the surface of TiI2 nanorod were constructed through the second hydrothermal process,and the influence on the photoelectrochemical properties was been discussed in detail.Specific research contents are as follows:Hetero-structured TiI2 nanotree arrays on flurine-doped tin oxide(FTO)substrates were deposited by a two-step hydrothermal method,CdS/ZnS core-shell quantum dots(CdS/ZnS QDs)were deposited by a successive ionic layer absorption and reaction(SILAR)process.The TiI2 nanotree array is composed of a trunk-branch structure where the trunk is rutile TiI2 nanorod array and the branch is anatase TiI2 nanosheets standing on the trunk.Morphology,optical properties and photoelectrochemical(PEC)performances were investigated in detail.After the deposition of CdS/ZnS QDs,TiI2 nanotree array photoanode shows much better PEC performance compared to TiI2 nanorod array photoanode.The sensitized nanotree array show a higher photocurrent desity(1.5 mA/cm2)at 1.0 V and almost 2-fold current density(0.29 mA/cm2)than sensitized nanorod array(1.0 mA/cm2 and 0.15 mA/cm2)in the measurement of linear sweep voltammetry(LSV)and transient photocurrent,respectively.This result is due to the enlarged surface specific area for more quantum dots loading,and also due to the rutile/anatase junctions formed on the boundary of trunks and branches,leading to an effective charge separating and transporting.It suggests that the hetero-structured TiO2 nanotree array is very promising to be applied in highly efficient photoanodes for energy devices.MoS2 nanoplates(MNP)modified highly ordered TiO2 nanorod array(TNR)thin film with large contact interfaces and heterojunctions is developed by a simple two-step hydrothermal method.The morphology of MoS2 shows a transition from nanoplates to nanospheres(MNS)as the amount of precursor increase.For further comparison,different ratio of MoS2 was grown on TNR by changing the usage of the single-source precursor.The optimal MoS2/TiO2 electrode exhibits highest photocurrent density(0.293 mA/cm2)and photocatalytic degradation rate constant(9.21×10-3/min)for degrading Rhodamine B(RhB),which is 9 and 2.4 times higher than that of bare TiO2 electrode,respectively.It may due to the contact interfaces and heterojunctions between MoS2 and TiO2,which can accelerate the transfer of charges and restrain the recombination rate of electron-hole(e--h+)pairs.These results indicate that the MoS2/TiO2 thin film has potential applications in water splitting and solar cells. |
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