Collaborative Research: Environmental Electron Doping of Iron Oxide Nanoparticles: Influence on Particle Properties and Reactivity

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This award is funded jointly by the Environmental Chemical Sciences (ECS) Program in the Division of Chemistry and the Geobiology and Low Temp Geochemistry Program in the Division of Earth Sciences. Professor Scherer (University of Iowa, UI) and Professor Tratnyek (Oregon Health Sciences University) study the electrochemical behavior of iron oxides in soil and water. Iron oxides are found in virtually all surface environments on Earth, and have also been identified on the surface of Mars. These tiny, often nano-sized (1 billionth of a meter), particles are also major components of paints, steel, and batteries. Despite their environmental and technological relevance, the electrochemical behavior of iron oxides in the environment remains poorly understood. The goal of the project is to understand the behavior of iron oxide nanoparticles in water and soil. This understanding may help environmental chemists and engineers address important water quality issues such as arsenic in groundwater and develop alternative methods for low-cost, low-energy water treatment. This work aids in the protection of public health by advancing predictions of chemical exposure from surface and ground waters. It also provides important insights into how land use changes impact climate change, as carbon is often directly bound to iron oxides in soils. The graduate students at UI working on this research project are part of the NSF Research Traineeship (NRT) program in Sustainable Water Development. Professors Scherer and Tratnyek develop and lead educational outreach efforts to K-12 students and water treatment professionals. Professor Scherer uses LEGO Molecule Kits to develop hands-on activities for students to learn about environmental reactions and Professor Tratnyek workshops for technical training certification for wastewater and water operators at a local community college. The results from this research may help protect public health by providing new knowledge on how to minimize exposure to contaminants in water (e.g., arsenic, which is linked to iron oxide solubility) and manipulate iron availability to raise primary productivity of oceanic waters. It is well known that iron (Fe) oxides are semiconductors and that their properties and behavior can be altered significantly by introducing trace impurities, i.e., doping. It is, however, still unclear to what extent electron doping of iron oxides occurs in the natural environment. The goal of this project is to determine whether iron oxide nanoparticles can be doped with electrons from reaction with natural chemical species, such as ferrous iron and sulfide, and how doping alters iron oxide properties and reactivity. Advanced spectroscopic and electrochemical techniques are used to measure changes in electronic or magnetic particle properties, such as band gap and Mössbauer transition temperatures. In addition, a suite of electrochemical methods is used to measure the redox properties of the particles. The reactivity of electron doped nanoparticles is measured with respect to contaminant oxidation, contaminant reduction, and dissolution. in additional to possible impacts in the environment, this research may also provide new insights on the material properties of Fe oxide which can be used to develop innovative, cost-effective batteries for energy storage and conversion.