功函数是金属光阴极的一项重要特性,决定了光电子发射量子效率。金属表面在大气环境中容易受表面吸附污染的影响,从而改变表面功函数,并可能影响光电子发射性能。本工作通过光电子能谱的方法,研究常用做光阴极材料的多晶铜和金表面在大...功函数是金属光阴极的一项重要特性,决定了光电子发射量子效率。金属表面在大气环境中容易受表面吸附污染的影响,从而改变表面功函数,并可能影响光电子发射性能。本工作通过光电子能谱的方法,研究常用做光阴极材料的多晶铜和金表面在大气环境中的吸附污染,及其对表面功函数的影响。根据紫外光电子能谱的测量,发现铜和金金属表面存在吸附污染时功函数相比纯净金属表面分别降低约0.1 e V和0.7 e V。利用X射线光电子能谱分析发现有机分子吸附污染使得金样品的表面功函数降低;而对于铜样品表面,导致功函数降低的因素包括有机分子吸附和表面氧化。本研究对光阴极的应用具有指导意义。展开更多
Titanium dioxide（TiO2） is one of the most widely studied transition metal oxides, especially for its unique performances in heterogeneous photocatalysis. Different phases of TiO2 have been found to exhibit different...Titanium dioxide（TiO2） is one of the most widely studied transition metal oxides, especially for its unique performances in heterogeneous photocatalysis. Different phases of TiO2 have been found to exhibit different photo-activities, though the origins are still not fully understood. In this work, we use the density functional theory（DFT） calculations, corrected by on-site Coulomb and long-range dispersion interactions, to study the adsorptions of nitric oxide（NO） and oxygen（O2） molecules on the clean and hydrogenated anatase TiO2（101） surfaces. We also compare the detailed calculated results regarding their structural, energetic and electronic properties with those obtained at rutile TiO2（110）. It has been found that the behaviors of the surface localized electrons being transferred from adsorbed H, as well as the adsorption behaviors of NO and O2 are quite different at the two surfaces, which can be attributed to their characteristic local bonding structures around the surface hydroxyl. These results may also help explain the different photocatalytic activities of these two main facets of anatase and rutile TiO2展开更多
电化学/电催化技术是实现能源高效转化与储存的重要手段,并已经发展成为一个国际前沿领域。如今日渐深入的电催化研究开始要求更精确且多维度的电化学界面信息,从而指导实现电化学体系的优化,而这往往依赖于一些原位表征方法的发展和应...电化学/电催化技术是实现能源高效转化与储存的重要手段,并已经发展成为一个国际前沿领域。如今日渐深入的电催化研究开始要求更精确且多维度的电化学界面信息,从而指导实现电化学体系的优化,而这往往依赖于一些原位表征方法的发展和应用。电输运谱(electrical transport spectroscopy,ETS)是一种新兴的基于芯片平台的电化学原位表征技术,它可以实现电势扫描条件下电化学信号和电极材料电输运性质的同时获取。本文首先介绍了基于铂纳米线微纳器件的ETS信号原理(吸附现象导致的表面电子散射)和器件制作流程、几个典型电催化反应过程中铂表面状态的演变,以及电解质离子竞争吸附对铂催化氧还原反应动力学过程的影响。由于与电化学体系的高度匹配,ETS可应用于不同结构及金属类型材料体系(金和铂纳米颗粒)。金和铂表现出显著不同的离子吸附现象,尤其是对于弱吸附离子(高氯酸根和硫酸根)。通过电输运谱还可实时监测电化学过程中材料的相变及电子性质的变化。于是,ETS可被用于监测和实现二维材料电化学可控插层,理解电催化剂在电催化过程中的相变机制以及相变过程如何影响电催化活性,揭示二维半导体催化剂材料电催化过程的自门控效应。此外,ETS还被应用于生物电化学体系,探索电化学过程中的细胞导电机制。最后,本文对ETS的优点及不足进行总结,展望了ETS在未来电化学领域所面临的挑战和机遇。展开更多
Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by...Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by eutrophication. The co-existence of surface adsorbed and intracellular phosphorus pools indicate that phosphate uptake by phytoplankton is, to some extent, a two-stage kinetic process. However, almost all previous uptake models considered the internal uptake stage only and ignored the possible impact of surface adsorption. In this article, a two-stage kinetic uptake model considering both surface adsorption and P-stress on phosphate uptake by algae was constructed and compared to conventional one-stage models, based on experimental data on short-term uptake kinetics of a green algae S. quadricauda. Results indicated that with suitable parameters, the two-stage uptake model not only fit the experimental data better, but also gave more reasonable and realistic explanations to the phosphate uptake process. The results are meaningful as surface-adsorption of phosphate may affect the uptake process of phosphate and assist in understanding realistic phosphate uptake kinetics in phytoplankton.展开更多
文摘功函数是金属光阴极的一项重要特性,决定了光电子发射量子效率。金属表面在大气环境中容易受表面吸附污染的影响,从而改变表面功函数,并可能影响光电子发射性能。本工作通过光电子能谱的方法,研究常用做光阴极材料的多晶铜和金表面在大气环境中的吸附污染,及其对表面功函数的影响。根据紫外光电子能谱的测量,发现铜和金金属表面存在吸附污染时功函数相比纯净金属表面分别降低约0.1 e V和0.7 e V。利用X射线光电子能谱分析发现有机分子吸附污染使得金样品的表面功函数降低;而对于铜样品表面,导致功函数降低的因素包括有机分子吸附和表面氧化。本研究对光阴极的应用具有指导意义。
基金financial support from the National Natural Science Foundation of China (Nos. 21421004, 21573067, 91545103)Program of Shanghai Academic Research Leader (No. 17XD1401400)
文摘Titanium dioxide（TiO2） is one of the most widely studied transition metal oxides, especially for its unique performances in heterogeneous photocatalysis. Different phases of TiO2 have been found to exhibit different photo-activities, though the origins are still not fully understood. In this work, we use the density functional theory（DFT） calculations, corrected by on-site Coulomb and long-range dispersion interactions, to study the adsorptions of nitric oxide（NO） and oxygen（O2） molecules on the clean and hydrogenated anatase TiO2（101） surfaces. We also compare the detailed calculated results regarding their structural, energetic and electronic properties with those obtained at rutile TiO2（110）. It has been found that the behaviors of the surface localized electrons being transferred from adsorbed H, as well as the adsorption behaviors of NO and O2 are quite different at the two surfaces, which can be attributed to their characteristic local bonding structures around the surface hydroxyl. These results may also help explain the different photocatalytic activities of these two main facets of anatase and rutile TiO2
基金support by the Natural Science Foundation of China (22172075)the Fundamental Research Funds for the Central Universities in China (0210/14380174)the “Innovation and Entrepreneurship” program and Jiangsu Province。
文摘电化学/电催化技术是实现能源高效转化与储存的重要手段,并已经发展成为一个国际前沿领域。如今日渐深入的电催化研究开始要求更精确且多维度的电化学界面信息,从而指导实现电化学体系的优化,而这往往依赖于一些原位表征方法的发展和应用。电输运谱(electrical transport spectroscopy,ETS)是一种新兴的基于芯片平台的电化学原位表征技术,它可以实现电势扫描条件下电化学信号和电极材料电输运性质的同时获取。本文首先介绍了基于铂纳米线微纳器件的ETS信号原理(吸附现象导致的表面电子散射)和器件制作流程、几个典型电催化反应过程中铂表面状态的演变,以及电解质离子竞争吸附对铂催化氧还原反应动力学过程的影响。由于与电化学体系的高度匹配,ETS可应用于不同结构及金属类型材料体系(金和铂纳米颗粒)。金和铂表现出显著不同的离子吸附现象,尤其是对于弱吸附离子(高氯酸根和硫酸根)。通过电输运谱还可实时监测电化学过程中材料的相变及电子性质的变化。于是,ETS可被用于监测和实现二维材料电化学可控插层,理解电催化剂在电催化过程中的相变机制以及相变过程如何影响电催化活性,揭示二维半导体催化剂材料电催化过程的自门控效应。此外,ETS还被应用于生物电化学体系,探索电化学过程中的细胞导电机制。最后,本文对ETS的优点及不足进行总结,展望了ETS在未来电化学领域所面临的挑战和机遇。
基金supported by the National Major Projects on Control and Rectification of Water Body Pollution(No. 2009ZX07106-001)the National High Technology Research and Development Program (863) of China(No.2006AA10Z411)the National Basic Research Program (973) of China(No. 2008CB418000)
文摘Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by eutrophication. The co-existence of surface adsorbed and intracellular phosphorus pools indicate that phosphate uptake by phytoplankton is, to some extent, a two-stage kinetic process. However, almost all previous uptake models considered the internal uptake stage only and ignored the possible impact of surface adsorption. In this article, a two-stage kinetic uptake model considering both surface adsorption and P-stress on phosphate uptake by algae was constructed and compared to conventional one-stage models, based on experimental data on short-term uptake kinetics of a green algae S. quadricauda. Results indicated that with suitable parameters, the two-stage uptake model not only fit the experimental data better, but also gave more reasonable and realistic explanations to the phosphate uptake process. The results are meaningful as surface-adsorption of phosphate may affect the uptake process of phosphate and assist in understanding realistic phosphate uptake kinetics in phytoplankton.
