Preparation And Properties Of CdSe/TiO₂Coaxial Nanocables

In this dissertation, CdSe nanowires, CdSe nanotubes and CdSe/TiO2coaxialnanocables have been produced using electro-deposition method in AAO templates.Their structures, morphologies and optical absorption properties were characterizedwith scanning electon microscopy, transmission electron microscopy, EDS spectra,X-diffraction and UV-vis absorption spectrum.The CdSe nanowires and nanotubes were assembled in the AAO templates byusing potentiostatic method. SEM and TEM photos show the sample was abundant,uniform and highly ordered over a large area. The external diameter of the CdSenanotubes was about100nm, wall thickness was about20nm and the diameter ofCdSe nanowires was about100nm. The result of XRD analysis indicates that therewere two structure, cubic structure and hexagonal structurs. The temperature of CdSenanomaterials transform from cubic structure to hexagonal structure was350oC. TheMott-Schottky curve indicated that CdSe nanomaterials was a n-type semiconductor.TiO2nanotubes arrays were firstly prepared by the electrochemical method inAAO templates from inorganic aqueous solution, then CdSe nanowires weredeposited in TiO2nanotubes arrays and finally CdSe/TiO2coaxial nanocableselectrode were obtained. SEM and TEM indicated that TiO2nanotubes completelyfilled by CdSe nanowires, which showed coaxial nanocables structure. The externaldiameter of coaxial nanocables was about100nm, wall thickness was about20nm.The diameter of the CdSe nanowires was about60nm. The absorption edge ofcomposites showed an obvious red-shift and absorption peak was appeared in thevisible light region. Photocatalytic performance test showed that, comparing with theTiO2nanotube arrays, the open circuit potential of CdSe/TiO2coaxial nanocablesreached the maximum. Photocatalysis degradation efficiency of the coaxialnanocables arrays reached98.71%after7hours, even better than the TiO2nanotubesarrays. The photocatalytic hydrogen generation showed that the rate of photocatalytichydrogen production of the CdSe/TiO2coaxial nanocables was3.77×10-6mol/s,averaged quantum yield was51.26％, averaged photon-hydrogen energy conversionefficiency was29.69％, even better than the TiO2nanotubes arrays and CdSenanowires arrays.