Fundamental Redox Reactivity at Binary Nanoparticle/Solution Interfaces

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Prof. James Mayer of Yale University and his team will examine changes that can occur at the surfaces of very small particles (nanoparticles). The nanoparticle surfaces bind electrons and various atoms, such as hydrogen (H). The surface-bound species can then be transferred to other materials. The work will start with simple questions, such as: how many H atoms can bind to the surface? Do they all bind with the same strength, or does the first H added bind more strongly and then as the surface gets more crowded the binding gets weaker? Can an H atom on the surface release a proton (H+) to the solution, with the e- staying on the particle, and how would this affect the H that remain on the surface? The answers to these questions are the foundation of many important processes, such as using of more earth-abundant and sustainable materials for energy applications. This project will include outreach to engage the broader community on the topics of energy and nano-chemistry, through research internships in the Mayer laboratories and through week-long summer programs for high-school students from the diverse south-central Connecticut region. Prof. Mayer and the graduate students, undergraduates, and postdoctoral fellows in his laboratory are all excited to share what is different about very small particles, of only a few hundred or thousand atoms (‘nano-science’). They will also emphasize why it is important to understand basic science – how many H can be added? – to broadly advance science and technology. The surfaces of nanoparticles are typically irregular and rough, with lots of edges and corners. This particularly occurs when the particles are made of different kinds of atoms, such as tungsten oxide with tungsten (W) and oxygen (O) atoms. This research aims to find order in this complexity. It aims to understand the connections between the number of adsorbed atoms, how strongly they bind, and how fast they can be added or removed. The work will emphasize two of the simplest reactions, transfer of H or O, with three different materials, tungsten oxide, iron carbide, and cobalt phosphide. Understanding the similarities and differences between these materials will show what properties are common at the nanoscale, and what properties can be adjusted by choosing different materials. 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.