【作者】 李贺；

【导师】 姚素薇；

【作者基本信息】 天津大学 ， 应用化学， 2007， 博士

【摘要】 本论文是以光电化学太阳能电池的半导体光电极（包括光阳极和光阴极）的制备、表征与光电性能研究为主要内容,通过各种测试技术和光电化学研究手段,对TiO₂纳米管阵列光阳极的制备、形成机理和有关光电性能进行了较系统的研究;另外还对金属（合金）/p-Si、Ni-Co/AC和Ni-W-P/TiO₂等阴极材料的催化析氢性能进行了研究。采用阳极氧化法在钛片上成功获得了排列规则的、垂直导向生长的TiO₂纳米管阵列。最佳反应工艺条件为:阳极氧化电压20 V,HF电解液浓度1（wt）%,室温,反应时间控制在30 min。在此条件下制得的TiO₂纳米管阵列,其管内径约为90 nm,管壁厚约为10 nm,氧化膜厚度约为500 nm。通过XRD分析和计算得出,经600℃退火处理后,电极结构为锐钛矿型与金红石型的混晶结构。光电化学测试结果表明,TiO₂纳米管阵列电极具有n型半导体的典型特征。经600℃退火处理的纳米管电极开路电压最大,电荷转移电阻最小,所表现出的光电响应特性与普通TiO₂多孔膜电极基本相似。但TiO₂纳米管阵列光电极具有更高的光电转换效率。其主要原因是纳米管阵列电极独特的管状阵列结构,比多孔膜电极具有更大的孔隙率和比表面积。采用溶胶-凝胶法制备不同过渡金属离子掺杂TiO₂纳米管光电极,其光电响应区别很大。在电极电位为0.6 V时,掺杂电极光电性能由大到小的顺序依次为:Zn > Cu > Ni > Fe > Mn。这主要是由掺杂过渡金属离子本身的物理化学性质的不同而引起的。实验结果证实,Ea/r值适中、磁矩值越小的ZnOx/TiO₂电极体系具有更大的光电化学性能。采用化学沉积和电沉积技术制备了Pd/p-Si和Ni-Co-P/p-Si纳米晶光阴极。实验结果表明,光照使其析氢反应性能显著提高,p-Si电极表面纳米颗粒的覆盖度对其光电催化析氢性能有显著影响,纳米颗粒的表面覆盖度过小或过大均不利于光电催化析氢性能的提高,其存在一个最佳值。约为35%。采用复合电沉积技术制备了Ni-Co/AC复合电极材料。测试表明,Ni-Co/AC复合电极较Ni电极和Ni-Co合金电极具有更高的催化析氢性能,这主要归因于其真实表面积的增大。另外通过控电位沉积技术制备了Ni-W-P/ TiO₂纳米管复合电极材料。测试结果表明,该复合电极的析氢过电位比Ni-W-P合金电极降低130 mV,表现出更好的催化析氢性能。更多还原

【Abstract】 The purpose of this dissertation is to study the electrochemical preparation, characterization of photoelectrode （anode and cathode） of the photoelectrochemical solar cell （PEC）, and their photoelectrochemical properties. The influencing factors, formed mechanism, and related photoelectric properties of TiO₂ nanotubes array photoanode were systematically investigated based on multifarious measured techniques and photoelectrochemical research methods. And the properties for hydrogen evolution of metal （or alloy） /p-Si, AC/Ni-Co and Ni-W-P/TiO₂ photocathodes were investigated. The research contents and the gained chief achievements are as follows:TiO₂ nanotube arrays were successfully fabricated by anodic oxidation method on a pure titanium sheet. Optimal reaction conditions for preparation are as follows, 20 V for oxidation voltage, 1（wt） % for concentration of HF electrolytes, 30 min for reaction time and room temperature. In this condition, the aperture size of the nanotube arrays is about 90 nm; the thickness of tube wall is about 10 nm; and the length of nanotube is about 500 nm. The structure of these samples was characterized by XRD. The results show that the structure is a mixture phase of anatase and rutile annealed at 600℃, the rate of rutile phase is about 47.7%, and the average crystalline size is about 19.0 nm.The photoelectric measurement results show that the TiO₂ nanotube arrays electrode exhibits the typical property of the n-type semiconductor. The interfacial charge transfer resistance of the electrode annealed at 600℃is minimal, the photocurrent and the signal of open-circuit potential are maximal. Its photoelectric performances are similar with the ordinary TiO₂ porous films electrode. But the photoelectric conversion efficiency of the nanotubes electrode is higher than the porous films electrode. It was mainly due to the high porosity and the large real surface area of the TiO₂ nanotube arrays.The different transition metal ions （Fe, Mn, Ni, Cu, and Zn） doped TiO₂ nanotube photoelectrodes were prepared by sel-gol method. The results show that their photoelectric performances were different, and the order of their photocurrent ranked from the highest to the lowest is Zn > Cu > Ni > Fe > Mn. This paper argued that the difference of physical chemical quality of transition metal ions was the main factor of the results. When the TiO₂ nanotube electrode doped with Zn ions has a moderate value of Ea/r and a smaller magnetic moment, it shows much higher photoelectric performance.The nanocrystalline Pd modified p-Si and the Ni-Co-P alloy modified p-Si photocathode were prepared by electrochemical technology. The results show that the overpotential for HER of these photocathodes was reduced under illumination, and its catalytic properties were increased evidently. The investigation on relationship between surface fraction and HER current density of both electrodes indicates that the surface fraction of nanoparticles on p-Si electrode has an optimal value, and these optimal fractions of both electrodes are about 35 %.The Ni-Co/AC composite electrode was prepared by composite-electrodeposition. The results show that the Ni-Co/AC composite electrode is catalytically more active than the Ni and Ni-Co alloy electrode, which is mainly due to the increase in the real surface area of the electrode. The Ni-W-P/ TiO₂ nanotube composite electrode was prepared by electrodeposition at constant potential. The experimental results show that the overpotential for HER of the composite electrode is 130 mV lower than that of Ni-W-P alloy electrode, the former shows better properties for hydrogen evolution.更多还原