Cu₂O/TiO₂Nanocomposite: Preparation And Photoelectrochemical Property

Titanium dioxide is a n-type semiconductor material with stable physicaland chemical activity, high photocatalytic efficiency and nontoxiccharacteristics. There are increasing potential applications for anodic titaniumdioxide nanotube arrays in the new energy materials, dye-sensitized solar cells,photocatalytic degradation of organic pollutants and so on. Based on theconventional anodic oxidation of highly ordered titania nanotube arrays andhydrothermal synthesis of Cu2O nanoparticles, this paper focuses on thepreparation of superhydrophobic templates which are adopted for thecontrollable fabrication of Cu2O/TiO2heterojunctions through commonelectrodeposition method and pulsed electrodeposition process. The influencesof different process parameters on the morphology of Cu2O/TiO2aresystematically investigated. The photoelectrochemical properties of thecomposite nanomaterials are tested via the chemical working station. Themorphology, crystal structure and the elements of the samples are analyzed withfield-emission scanning electron microscopy (FESEM), high-resolutiontransmission electron microscopy (HRTEM), the X-ray diffraction (XRD) andX-ray photoelectron spectroscopy (XPS). The following conclusions could bedrawn:(1) During the conventional anodization process, well-aligned nanotubearrays could be fabricated on the Ti foils with the anodization voltage30to80Vand the reaction time2to10hours. In order to overcome the surface irregularityof the conventional anodized TiO2nanotube arrays, a two-step anodic oxidationmethod is developed. And the relationship between anodization voltage andmorphology is discussed. The results show that the better surface evenness ofthe as-prepared TiO2nanotube arrays could be achieved when50V+50Vanodization voltage is applied.(2) In order to explored favoralbe parameters for the electrodeposition ofcuprous oxide, cuprous oxide with different morphology is synthesized byhydrothermal reaction. Octahedron, decanedron, and tetrakaidecahedronstructured Cu2O are prepared with different pH value. The results shows that analkaline solution and a certain reaction time are needed for the growth of Cu2O nanoparticles. And the morphology of Cu2O could be influenced by the pHvalue.(3) The conventional potentiostatic electrodeposition process is employedfor the preparation of Cu2O/TiO2heterojunctions. The highly orderednanotubular structures are retained after the electrodeposion treatment. Whendifferent deposition voltage and pH value are applied, Cu2O nanoparticles withdifferent morphologies could be achieved. And the TiO2nanotube arraysmodified with the electrodeposited Cu2O nanoparticles exhibit greatly enhancedphotocurrent and photocatalytic properties.(4) The as-prepared Cu2O nanoparticles could not be evenly distributedonto the TiO2nanotube arrays when the conventional electrodepositiontechnique is applied. Then superhydrophobic TiO2nanotube arrays templatesand pulse electrodeposition method are further developed. The as-preparedsuperhydrophobic TiO2nanotube arrays are successfully decorated by uniformlydistributed Cu2O nanoparticles with the diameter15nm. The distributionuniformity and particle size of Cu2O nanoparticles are significantly improved.The experimental results show the photocurrent of Cu2O/TiO2heterojunction isnearly50times higher than that of the conventional TiO2nanotube arrays.