| In the PEC process, the solar conversion efficiency is mainly determined by thephotoelectrodes. Morphological and structural control of photoelectrode play an importantrole for enhancement of PEC properties.The development of photoelectrodes with high utilization of solar energy, high energyconversion efficiency and excellent stability is the key issue for PEC technology. Owing totheir unique morphologies and structure, low dimensional nanomaterials or nanocompositewith hierarchical structures, have been widely applied in photo-electrochemistry andelectrochemistry. The rapid recombination of photoinduced electrons and holes greatly limitsthe quantum efficiency of single photoelectrode matrial. In this dissertation, our work focusedon the synthesis of one dimensional, well organized arrays of semiconductive nanomaterials.We intend to improve the PEC properties of photoelectrode material by morphological andstructural control of photoelectrode matrials, as well as combination of two differentmaterials.The details are summerized briefly as follows:1. Firstly, TiO2nanorod arrays on FTO substrate were synthesized by hydrothermalprocess. After that, a facile thermal polycondensation process in half closed reactor wasconducted for the deposition of g-C3N4nanoparticles onto TiO2nanorod arrays. PECmeasurements were proformed with the g-C3N4/TiO2NRs nanocomposites. The experimentresults indicate that, after introducing g-C3N4, the absorption spectrum of the composite isexpanded to visible region of solar spectrum, the flat band shifted to a more negativepotential, and the donor density was also greatly increased. The one dimensional structureprovided direct path way for the transfer of electrons. Thus, the recombination ofphoto-induced electrons and holes was hindered, the PEC properties were greatly enhanced.2. ZnO nanotube arrays on FTO substrate were prepared by two-step electrochemicalprocesses. And then, g-C3N4nanoparticles were deposited into the interspaces of the ZnOnanotube arrays or into the inner wall of the ZnO nanotubes to provide more contact sites forZnO and g-C3N4. After coupling of ZnO nanotube arrays and g-C3N4, the flat band shifted toa more negative potential, and the donor density was also greatly increased. The one dimensional structure provided direct path way for electrons transfer, so the recombination ofphoto-induced electrons and holes was hindered, thus greatly enhanced the PEC properties.3. CuO nanoplatelets were synthesized on Cu substrate by a hydrothermal oxidationprocess, and then ZnO nanoflowers were grown on the CuO nanoplatelets by a three-stepprocedure consisting of etching, seed nucleation and hydrothermal growth. Theelectrochemical properties and photoelectrochemical properties of the ZnO/CuO areinvestigated. The PEC properties were greatly enhanced under visible light irradiation. This isattributed to the large contact area with the electrolyte and high conductive pathway forcharge carrier collection of the nanocomposite as well as the synergistic effect between thetwo components. The ZnO/CuO nanocomposite holds great potential for application for solarenergy conversion.4. Hierarchically branched ZnO/CuxO heterostructure was fabricated through a simplewet chemical method combined with a hydrothermal process. Under visible light irradiation,hierarchically branched ZnO/CuxO photoelectrode showed enhanced PEC properties. Theadhesive growth of ZnO nanowires on the CuxO backbones greatly improves the exposedsurface area, and the one-dimensional ZnO nanowires continuously provide conductivepathways for the transfer of photo-induced electron.5. The CuO nanoplatelets were fabricated on Cu foil by a one-step hydrothermal process.The attached growth of CuO nanoplatelets on Cu foil is easy to be integrated as an electrodefor enzyme-free sensing of glucose. An excellent selectivity, good stability, high sensitivityand anti-interference property was obtained, and the facile and quick determination ofglucose concentration is realized. |
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