Reseach On The Preparation And Doping Modification Of CdTe/TiO₂Nanotube Array Coaxial Heterojunctions

The energy crisis and environmental pollution have become two major pressingglobal problems that put forward the huge challenges to the survival of the human.However, using the photocatalytic technology can effectively solve the two majorproblems, because it can not only effectively splitting water that achieve converting solarenergy into clean and renewable hydrogen which instead of oil, coal and othernon-renewable energy, but also can effectively degrade organic pollutants to somepollution-free substances such as CO₂, H₂O and so on. Thus, photocatalytic technology isan efficient path to thoroughly solve the current energy and environmental problems.TiO₂nanotubes film has many advantages so that other materials cannot replace it,such as no pollution, recycling，high specific surface area，good stability, high quantumefficiency and so on, which making TiO₂nanotubes array has the great applicationprospect in the photo catalytic field. Firstly, we improve the preparation process oftitanium dioxide nanotubes arrays, which clear nanowires via etching its surface by theHF gas and HF aqueous solution and two-step anodic oxidation. The result shows that weobtained highly-ordered titanium dioxide nanotubes arrays of110-nm pore diameter,15-nm wall thickness, and22-μm length were grown perpendicular to titanium substrateby two-step anodic oxidation of a titanium thin film. under100mW/cm²illumination thegenerated photocurrent is2mA/cm², with a photocurrent efficiency of2.29%.Because the activation of pure TiO₂nanotubes array is limited only in the UV region,which accounts for only4⁵%of the spectrum of solar energy, its photoconversitionefficiency is not very high. And sensitizing TiO₂nanotubes array with a narrow-band-gapsemiconductor material can enhance its visible spectral response. In this paper, weprepare CdTe/TiO₂nanotubes array coaxial heterojunction by electrochemical atomiclayer epitaxy and electrochemical co-deposition method, discuss the effect of depositionpotentials, annealing and deposition charge amounts on its properties. The experimental results show that CdTe/TiO₂nanotubes array coaxial heterojunction with8C CdTedeposited at-0.65V and annealed20minutes at300℃showed maximumphotoelectricity conversion rformance, its photoconversition efficiency can achieve7.64%。To further improve the photoconversion efficiency of CdTe/TiO₂nanotubes arraycoaxial heterojunction, we study the effects of Zn addition on the photoelectric propertiesof CdTe/TiO₂nanotubes array coaxial heterojunction. The recent study shows that it caneffectively improve its photoelectric performance when the dpped position of Zn is in theinside of CdTe extension sensitization and near its surface, and the best deposition chargeamounts of Zn is0.4C. The photoconversion efficiency of Zn doped CdTe/TiO₂nanotubes array coaxial heterojunction according to the structure design can achieve14.8%.