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）项目的支持下，内华达大学里诺分校的Mario Alpuche博士正在研究半导体纳米颗粒表面的光驱动反应的极限。纳米粒子比这句话末尾的句号大约小一百万倍，它们表现出独特的特性，使它们在从消费电子到化学传感器的各种技术中都很有用。Alpuche教授和他的学生们一起使用纳米电极来研究光吸收后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。Alpuche博士还与内华达大学合作，该大学招募本科生成为K-12科学教师，并通过与西部联盟合作，提高学生机会（WAESO）计划，他为北内华达州的西班牙裔学生提供研究机会，激励他们从事化学职业。Mario Alpuche博士的研究小组正在研究光电化学器件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，TiO2和CdSe纳米粒子附着在纳米电极上，用光激发，产生电子-空穴对。当电极检测到光产生的电子作为电流时，价带中的空穴可以被溶液中分子的电子转移填充，或者它可以被困在表面缺陷处。然后测量光感应电流作为电化学电位和光强度的函数。电子-空穴复合、空穴捕获和电荷转移过程是通过模拟他们的实验观察用有限元模拟解开。此外，该小组继续推进电化学仪器，包括制造纳米尺寸的新电极，以提高该技术的灵敏度。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.