The Macromolecular, Supramolecular and Nanochemistry (MSN) program of the Division of Chemistry will support the research program of Prof. Marjorie Langell of the University of Nebraska-Lincoln. Prof. Langell and her students will study the effects of composition and size on the magnetic properties and chemical reactivity of bi-metallic transition metal oxide nanoparticles using state-of-the-art computational and experimental spectroscopic methods including ones that are only available in synchrotron facilities. The study is potentially transformative since it could lead to significantly improved properties of nanoparticles in a wide range of applications including magnetic memory and electronic devices, battery technology, photocatalysts and gas sensors. The study will be provide excellent training opportunities to undergraduate and graduate students in a cutting edge research area that bridges fundamental science with nanotechnology.
The goal of the project is to develop a new class of materials with tunable physical and chemical properties through size and compositional variation. Metal Oxide Solid Solutions: Macroscopic to Nanoscale, has studied bimetallic metal oxides of the general form MxM'(1-x)O where M and M' are different metals and x is the compositional variable, to elucidate the effect of composition as the dimension of the crystallite size is varied from large (macroscopic) to atomically-small (nanoparticle) size. As crystallite dimensions decrease to the nanometer scale, the system can change dramatically, often in ways that do not simply extrapolate from bulk structure, composition and bonding. Mixed-metal oxides, which contain two or more different metals in variable ratios, are a particularly attractive class of materials since their properties can be tailored extensively through compositional variability, making them adaptable to a wide range of applications and operating conditions. Solid solutions form when one metal, the "guest" cation, randomly replaces another in the host metal oxide structure, changing both the structural and chemical properties of the oxide continuously as the concentration of guest is increased. We have developed protocols for the synthesis of a number of solid solutions, ZnxNi(1-x)O, CuxNi(1-x)O, NixFe(3-x)O4, CuxPd(1-x)O and YbxY(2-x)O3, across a range of particle sizes, and have investigated their structural, compositional and chemical reactivity properties. While single point compositions of a few oxide solid solutions have been previously studied, the work in this proposal has intellectual merit as being the first to investigate routes to fabrication of binary oxide solid solutions systematically and to correlate their structural, chemical and magnetic properties with guest concentration and with particle size. The project was carried out to meet the broader impacts goals of integrating research and education for development of a diverse and globally competative STEM workforce.1 Over her years at UNL, the P.I.'s research group has averaged 40% female, and has comprised black, Hispanic, Asian-American and other ethnic groups. Training is extensively tailored to the student's research goals and career aspirations. As part of the outreach component to this project, the P.I. and her group were involved in activities designed to increase public awareness. As a group effort, we participated in Nano-days, organized by UNL's Nebraska Center for Materials and Nanostructures (NCMN). Nano-days is an all-day event, held on a Saturday in a popular local shopping mall, and brings the concept of nanotechnology to the general public. The event includes demonstrations and posters, and hands-on projects for children. The P.I. also encourages high school students to pursue undergraduate chemistry degrees by participation in Chemistry Day. Chemistry Day is a UNL Chemistry Department-sponsored event for high school students and their teachers. This event brings about 100 students to the department to tour labs, enjoy demonstrations and participate in chemistry quiz bowls and projects, with an aim of increasing the number of chemistry majors at UNL. Nebraska is primarily an agricultural state, and many high-schoolers do not consider chemistry as a career simply because they do not know anyone who is a chemist. Chemistry Day and Nano-days are two ways that the P.I. hopes to change this and make an impact on young, potential scientists to consider chemistry as a field of study. There is broader impact across many fields of science and technology for the results of this project. Advances in materials chemistry have benefitted society greatly, and a number of improvements has come as a direct result of the discovery of new and improved materials for technological applications. The binary oxides investigated here have applications to oxidation catalysis. Oxidation catalysis is used extensively in the energy sector in natural gas power generators, in solid-state fuel cells, and in petrochemical cracking. There are also applications in pollution abatement, in photochemical (solar) chemistry and in medicinal chemistry for imaging and drug delivery. 1NSF Document number NSF11047, "Empowereing the Nation through Discovery and Innovation: NSF Strategic Plan for Fiscal Years (FY) 2011-2016, National Science Foundation, Arlington VA 22230, April 2011.
