Enhanced Visible Light Photoelectrochemical Performances with Nitrogen Doped TiO_2 Nanowire Arrays

成功制备了氮掺杂锐钛矿TiO2纳米线,并研究了它的光电化学性质.结果表明,与商用P25 TiO2纳米粒子和未掺杂TiO2纳米线相比,氮掺杂TiO2纳米线作为光阳极明显地提高了光电转换效率(IPCE%),在可见光区有明显光吸收;在100 mW/cm2可见光光照下,氮掺杂TiO2纳米线具有最大的光电流密度和能量转换效率.例如,当电压为0.09 V(vs.Ag/AgC l)时最大能量转换效率为0.52%,均高于未掺杂TiO2纳米线和商用P25 TiO2纳米粒子的,充分表现出它优越的光响应和光电化学性能,在光电化学池、太阳能制氢等方面具有广泛的应用前景.Self-organized anodic anatase TiO2nanowire arrays doped with nitrogen have been successfully fabri-cated and their photoelectrochemical(PEC) properties have been characterized and found to be substantially im-proved compared to undoped nanowires or commercial P25 nanoparticles.Photocurrent measured with monochro-matic incident light showed that the incident photon-to-current efficiency(IPCE,%) values of nanowire arrayelectrodes with or without N-doping were obviously higher than that of commercial P25 nanoparticle electrodes,and nitrogen-doped TiO2nanowire arrays(NTNA) had noticeable absorption in the visible region.The NTNAelectrodes showed the highest photocurrent density and power conversion efficiency under 100 mW/cm2visiblelight illumination.A maximumolphotoconversion efficiency of 0.52% was achieved for the NTNA sample at anapplied potential of 0.09 V versus Ag/AgCl(saturated KCl) electrode under visible illumination,much higherthan that of the undoped nanowire and commercial P25 nanoparticle electrodes.These results demonstrate thatNTNA thin films are promising for enhancing the photoresponse and effectively improving PEC performances ofnanostructured TiO2in the visible region for different applications including solar hydrogen generation.作者联系地址：清华大学化学系;美国加利福尼亚大学Santa Cruz分校化学与生物化学系;Author's Address: 1.Department ofChemistry,Tsinghua University,Beijing100084,China;2.Department ofChemistry and Biochemistry,University ofCalifornia,Santa Cruz,California95064,US

BOT案之資本預算投資決策分析－以宜蘭砲台山觀光景點為例

[[abstract]]近年來國際觀光的興貣帶動國內旅遊風氣，但我國又因經常性財政支出增加，導致財政困窘，因此開發大型公共建設大多採用與民間機構共同合作的BOT合作方案。BOT的基礎建設通常包含了許多的不確定風隩，政府會因要減少經常性支出的增加而進行BOT公共建設方案，但在進行投資時，會經過嚴密的評估方式。一般多採用傳統評價方式，但在評估分析中，忽略了許多投資時環境變動的不確定風隩，造成投資上的損失。台灣BOT案除了面臨財務面的不確定性因素之外，亦充滿其他的不確定性因素，如政府政策的改變、民意的衝擊等等，在受到其他因素之影響，發生了許多的問題，如弊案、執行偏差等問題，本研究運用二項式選擇權評估，評估結果是否有利可圖且能吸引民間機構投資此BOT計畫，並以宜蘭砲台山觀光景點BOT案為例加以探討

An Overview of Electrode Materials in Microbial Fuel Cells

微生物燃料电池以微生物为催化剂将化学能直接转化成电能，可用于废水处理并产生电能，是一种极具应用前景的生物电化学技术. 本文综述了近年来微生物燃料电池电极材料的制备、功能修饰及表面构建等的研究进展，着重介绍了炭基纳米材料的微结构与成分对微生物燃料电池性能的影响，并分析了微生物燃料电池电极材料现存的主要问题，以期不久的将来微生物燃料电池能付之实用.Microbial fuel cells (MFCs) are devices that can directly convert organic chemical energy into electrical energy with microbial as catalysts. MFCs are a promising bio-electrochemical system with the potential to degrade organic sewage and produce electricity. This article supplies a critical and comprehensive review for the electrode materials concerning about anode and cathode in MFCs, including the fabrications, functional modifications and surface constructions of electrode materials, as well as their applications in MFCs. Additionally, the existing problems of electrode materials in current MFCs have been demonstrated in order to provide the guideline for exploring the next-generation electrode materials for MFCs.高等学校博士点专项基金(No. 20110002130007)，973项目（No. 2011CB935704），国家自然科学基金项目(No. 20903055)，江西省自然科学基金项目(No. 2009GZH0085)和江西省教育厅重点项目(No. GJJ09019)资助作者联系地址：1. 南昌航空大学 江西省生态诊断修复与污染阻断重点实验室，南昌 330063； 2. 清华大学 微量分析测试方法与仪器研制北京市重点实验室，化学系，北京 100086Author's Address: 1. Key Laboratory of Jiangxi Province for Ecological Diagnosis-Remediation and Pollution Control, Nanchang Hangkong University, Nanchang 330063, China; 2. Department of Chemistry, Beijing Key laboratory of Microanalytical Detection Technique and Instrument Development, Tsinghua University, Beijing 10086,China通讯作者E-mail：[email protected], [email protected]

AC Impedance Study of the La 0.8 Sr 0.2 MnO 3/YSZ Electrode

用交流阻抗方法研究了Ｌａ０．８Ｓｒ０．２ＭｎＯ３（ＬＳＭ）电极上进行的氧电化学还原反应．实验表明反应速度控制步骤（ｒｄｓ）随反应温度、氧分压及过电位发生显著变化．近平衡下反应的ｒｄｓ为氧的解离吸附过程．强阳极极化下，电解质表面产生大量电子空穴；强阴极极化下，ＬＳＭ电极表面形成大量氧空位，二者的结果均使界面电导增加，电化学反应区扩展．低温强极化及高温强阳极极化下反应的ｒｄｓ为氧的电荷转移过程，高温强阴极极化下为氧的表面扩散过程Electrochemical reaction of oxygen on the La 0.8 Sr 0.2 MnO 3/YSZ electrode has been investigated in detail with AC impedance. The results demonstrated that the rate determining step(rds) of the reaction varies with the temperature, oxygen partial pressure and overpotential applied. At open circuit potential, the rds is the dissociative adsorption of oxygen on the LSM surface. A large number of electron holes are generated at high anodic overpotentials, while oxygen vacancies are formed at high cathodic overpotentials. The formation of the electron holes results in the electronic conduction of the YSZ electrolyte and the extension of the electrochemical active area. While the formation of oxygen vacancies leads to the ionic conduction in the LSM electrode and the extension of the electrochemical active area over the LSM electrode surface. The extension of active area and the increase of the conductivity induce some special phenomena reflected in AC impedance spectra, such as the decrease of both the electrode resistance and the ohmic drop, the increase of the double layer capacitance, and the appearance of the low frequency inductive arc at low temperature. The rds of the reaction at low temperature and high overpotentials is the charge transfer step, while at high temperature the rds of the reaction at high anodic and cathodic overpotential are the charge transfer step and the diffusion of oxygen over LSM surface respectively.作者联系地址：中国科学院大连化学物理研究所Author's Address: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 11602