【作者】 孙芳；

【导师】 王子忱；

【作者基本信息】 吉林大学 ， 物理化学， 2008， 博士

【摘要】 首先,通过条件控制制备出不同形貌的Cu2O薄膜,有三个主要形貌的薄膜形成:室温搅拌条件下,醋酸铜电解液中直接在ITO导电玻璃上电沉积出规则的树枝状结构的Cu2O薄膜;向醋酸铜电解液中加入简单盐作为形貌控制剂,发现含Cl-离子盐的加入能够明显改变Cu2O晶体的形貌,并且随着Cl-离子浓度的增加,Cu2O晶体的形貌从星形逐渐向方形结构变化;向醋酸铜电解液中加入CTAB、DTAC等阳离子表面活性剂作为添加剂来控制电沉积Cu2O晶体形貌的研究,发现Cu2O薄膜的形貌从星形、花瓣形到多孔球形结构的变化过程。同时,我们还讨论了形成不同形貌的可能机理。其次,我们对制备的薄膜进行了性能研究,发现树枝形结构的Cu2O薄膜在电催化氧化葡萄糖方面具有较好的性能,可作为无酶葡萄糖传感器的开发与应用;方形结构的Cu2O薄膜的表面光电压信号较强,在光电子器件方面有应用前景;多孔球形的Cu2O薄膜的光致发光性能较好,说明该结构的Cu2O薄膜在光学器件方面具有较好的应用前景。最后,利用已经制备好的Cu2O薄膜,通过一定的化学反应制备系列CuO薄膜和Ag/Cu2O复合薄膜。一方面Cu2O起到硬模板的作用,其形貌在CuO薄膜中可被成功复制;另一方面,通过简单化学方法,制得了Ag/Cu2O复合薄膜,为复合材料的制备提供了一种简单可行的方法。更多还原

【Abstract】 It is well-known that semiconductor materials are used extensively in many fields, such as aerospace industry and electronics industry. Cuprous oxide (Cu2O) is a metal-oxide p-type semiconductor with a band gap of about 2.0 eV, which has attracted much current interest because of its potential applications in solar energy conversion, catalysis and gas sensors. The applications of Cu2O thin films in other fields have not a well development, so, it is worth while to study the Cu2O thin films. Electrodeposition is a good solution process that can be applied in the growth of semiconductor films from aqueous or nonaqueous solutions. The advantages of electrodeposition compared with other techniques include low process temperature, economy, simplicity and possibility of making large area thin films. At present, the researches about morophogical control of electrodepositing Cu2O thin films on indium-doped tin oxide (ITO) glass substrate are mainly concentrate on Cu(NO3)2 and CuSO4 electrolytes. It has not a detailed research in Cu(Ac)2 electrolyte. So, we develop the technology of electrodepositing Cu2O thin film in an acetate bath directly on ITO glass substrate. By controlling reaction condition, we obtain Cu2O thin films with different morphologies and study the photoluminescence spectrum(PL), surface photovoltage spectroscopy(SPS) and electrocatalytical response to the oxidation of glucose properties of the prepared Cu2O thin films. We are searching for novel applications in other fields.The content and innovation of this thesis are listed as following: (1) We all know that the particle size and morphology of materials have a great impact on their performance. So, different morphologies of Cu2O thin films are prepared by controlling the reaction condition.(a) The effect of stirring of electrolyte on the growth of Cu2O films is studied under room-temperature. The stirring condition changes the direction and rate of crystal growth and rusults in Cu2O crystals with dendrite structure, which is obviously different from that obtained from static electrolyte. By increasing reaction temperature, growth rate of nucleus is greater than that of nucleation, which results in aggregation of crystals and reduced dendrite structure.(b) We study the effect of simple salts as controlling agents on the morphology of Cu2O thin films by electrodepositing in cupric acetate solution. We demonstrate that Cl- ions can change the Cu2O crystal morphology and the morphologies evolve from star-like to cube-like by increasing the concentration of Cl- ions of the capping agents. One formation reason of various shapes might be attributed to the adsorption of Cl- ions on different crystal faces and hindered the crystal growth perpendicular to the plane. The other formation reason might be the outcome of the interplay between the faceting tendency of the stabilizing agent and the growth kinetics (rate of supply Cu2+ to the crystallographic planes). (c) Novel well-defined Cu2O thin films are electrodeposited on ITO substrates by adding cationic surfactant (cetyl trimethyl ammonium bromide (CTAB) or dodecyl trimethyl ammonium chloride (DTAC)) with similar structure as shape controlled agents in cupric acetate solution. To the best of our knowledge, this research has not been reported before. The effects of the quantity of cationic surfactant, the temperature and concentration of electrolyte are studied. It is shown that the morphologies evolve from flower-leaves to spheres with increasing concentration of cationic surfactant (CTAB or DTAC). The formation mechanism of obtained different morphologies might be attributed to the adsorption of cationic surfactant (CTAB or DTAC), which in turn change the surface energies of different crystal faces and affect the growth kinetics. We believe that alkyl chains play a key role in controlling the morphologies of the electrodeposited Cu2O thin films than other ions effect during electrodeposition.We systematically study the effect of several reaction factors on the morphologies of electrodepositing Cu2O thin films in cupric acetate solution and multi-morphologies can be formed. The possible formation mechanism of different morphologies has been discussed.(2) The interactions between properties and structures are investigated. The obtained results are listed as following:(a) Cu2O thin films with star, cubic and dendrite structures as electrodes all have electrocatalytic response of the oxidation of glucose except for that with sphere structure. Cu2O thin films with dendrite structures have a better electrocatalytic response of the oxidation of glucose and high sensitivity compared with other structures, which reveal that they can be used to construct an enzymeless glucose sensor.(b) Cu2O thin films with star, cubic and dendrite structures as electrodes all have SPS property except for that with sphere structure. The reason of surface photovoltaic response might be attributed to the defects of Cu2O crystal structure and the impurity of Cu2O thin films. Cu2O thin films with cubic structures have a good photovoltaic response than other structures, which reveal a potential application in photoelectron devices.(c) Cu2O thin films with different morphologies by this electrodeposition all have different PL properties. This reason might be attributed to the defects of Cu2O crystal structure. We also find that Cu2O thin films composed of porous spheres have better PL properties and demonstrate potential optical applications.(3) CuO and Ag/Cu2O thin films have been obtained by the chemical reaction with the electrodeposited Cu2O thin films under certain conditions.The obtained results are listed as following:(a) CuO thin films can be prepared by heating the obtained Cu2O thin films, which can be reacted with oxygen. The colour of thin films changes from brick-red to black. And CuO thin films combine with ITO substrate still well. The morphology of CuO thin films can be controlled by the morphology of Cu2O thin films, which will improve the application in the field of apparatus.(b) Ag/Cu2O composite films can be obtained by certain chemical reaction with Cu2O thin films, which dip in low concentration H2SO4 and AgNO3 solution, respectively. The colour of thin films changes from brick-red to argentine. The morphology of Ag/Cu2O composite films also can be controlled by the morphology of Cu2O thin films. This approach combined the electrodeposition and chemical reactions and it can provide a simple and workable method to control the morphologies of other films by controlling Cu2O thin films.In conclusion, several morphologies of Cu2O thin films are obtained by electrodepositon in cupric acetate. The optical properties and electrocatalytic glucose properties are investigated and have better results. So, Cu2O thin films present potential applications in photoelectron devices and enzymeless glucose sensor. This approach combined the electrodeposition and chemical reactions can be used in other film prepration.更多还原