Single Nanoparticle Photoelectrochemistry: Effect of Electronic Structure and Metal Contact on Hole Transfer Rates

在化学系大分子、超分子和纳米化学(MSN)计划的支持下，内华达大学雷诺分校的Mario Alpuche博士正在研究半导体纳米颗粒表面光驱动反应的极限。纳米颗粒比本文末尾的句号小约一百万倍，它们表现出独特的性质，使其在从消费电子到化学传感器的一系列技术中都很有用。阿尔普切教授正在与他的学生合作，使用纳米电极来研究光吸收后在单个纳米颗粒表面发生的化学反应。他们的发现可能会带来将阳光转化为电能和化学燃料的新方法。此外，该项目正在培训下一代科学家开发和使用先进的电化学方法。阿尔普切博士还与招募本科生成为K-12科学教师的内华达教学公司合作，并通过与增强学生机会西部联盟(WAESO)计划的合作，为内华达州北部的拉美裔学生提供研究机会，激励他们追求化学职业生涯。马里奥·阿尔普切博士的研究小组正在研究光电化学设备中半导体纳米颗粒表面发生的基本电子转移事件。在他们的实验中，二氧化钛和镉硒纳米颗粒附着在纳米电极上，并用光激发，产生电子-空穴对。当电极将光生电子检测为电流时，价带中的空穴可以通过溶液中分子的电子转移来填充，或者它可以被捕获在表面缺陷位置。然后测量作为电化学势和光强的函数的光感应电流。利用有限元模拟模拟了电子-空穴复合、空穴捕获和电荷转移过程。此外，该小组继续推进电化学仪器，包括制造新的纳米尺寸的电极，以提高该技术的灵敏度。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry, Dr. Mario Alpuche at the University of Nevada-Reno is studying the limits of light-driven reactions at the surfaces of semiconducting nanoparticles. Nanoparticles are about a million times smaller than the period at the end of this sentence, and they exhibit unique properties that make them useful in technologies ranging from consumer electronics to chemical sensors. Working with his students, Professor Alpuche is using nanoelectrodes to study chemical reactions taking place at the surface of a single nanoparticle following the absorption of light. Their discoveries could lead to new ways of converting sunlight into electricity and chemical fuels. In addition, the project is training the next generation of scientists in the development and use of advanced electrochemcial methods. Dr. Alpuche is also partnering with NevadaTeach, which recruits undergraduate students to become K-12 science teachers, and through partnership with the Western Alliance to Enhance Student Opportunity (WAESO) program, he is providing research opportunities to Hispanic students in Northern Nevada, motivating them to pursue careers in chemistry. Dr. Mario Alpuche's research group is studying the fundamental electron transfer events that take place at the surfaces of semiconductor nanoparticles in photo-electrochemical devices. In their experiments, TiO2 and CdSe nanoparticles are attached to nanoelectrodes and excited with light, producing electron-hole pairs. While the electrode detects the photogenerated electrons as a current, the hole in the valance band can be filled by electron transfer from a molecule in solution, or it can become trapped at a surface defect site. The photoinduced current is then measured as a function of electrochemical potential and light intensity. The electron-hole recombination, hole-trapping, and charge transfer processes are disentangled by modeling their experimental observations using finite element simulations. In addition, the group continues to advance the electrochemical instrumentation, including the fabrication of new electrodes with nanometer dimensions, to improve the sensitivity of the technique.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.