CAS: Investigation of Earth-Abundant Metal Phosphides with Polyphosphide Anions as Catalysts in Hydrogen Evolution Reactions

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Energy and fuel consumption grow as society prospers. However, our reliance on fossil fuels is not sustainable and negatively impacts the environment. Hydrogen (H2) is a high energy fuel that releases energy upon its reaction with oxygen (O2) to produce water (H2O). Traditionally, hydrogen is produced from fossil fuels. Some materials can convert stable compounds, like water, into hydrogen using electricity or sunlight. These materials are known as catalysts (they make it easier to perform a chemical reaction without themselves being changed). Identifying strategies to increase catalyst efficiency to produce hydrogen can favorably impact US energy independence strategies. Currently, the most active catalysts for the production of hydrogen from water use expensive and rare metals like platinum. In this project, Dr. Gillan of the University of Iowa is developing new chemical syntheses to produce catalysts from metals such as nickel that are less expensive and more easily found in the environment. Dr. Gillan and his research students are examining new ways to split water into hydrogen using these catalysts aided by electricity or light energy input. Their experiments are improving understanding of how these catalysts function, which impacts future directions in effective catalyst design. Dr. Gillan is creating learning activities for undergraduate and K-12 students focused on industrially important materials and alternate energy processes, designing energy research opportunities for women and students from under-represented groups, and improving university laboratory safety culture at the University of Iowa. Dr. Gillan's project is jointly funded by the Chemical Catalysis Program (Division of Chemistry) and by the Established Program to Stimulate Competitive Research (EPSCoR). With funding from the Chemical Catalysis Program of the Division of Chemistry and by the Established Program to Stimulate Competitive Research (EPSCoR), Dr. Edward Gillan of the University of Iowa is developing a fundamental understanding of how surface reactions and redox chemistry of transition-metal phosphides with polyphosphide anions impact their catalytic activity in the important hydrogen evolution reaction (HER). A facile, solvent-free, thermochemically-driven synthetic strategy by the Gillan group allows access to earth-abundant phosphorus-rich metal phosphides with MP2 and MP3 compositions containing Fe, Co, and Ni metals. These crystalline metal phosphides are used directly or grown on supported structures for examination as HER catalysts in both electrochemical and photochemical environments. Experimentally observed differences in catalytic activity are correlated with key chemical, physical, and structural properties of the metal phosphides. The binding of reaction intermediates to the phosphide surface is investigated by solid-state nuclear magnetic resonance (NMR) and infrared spectroscopy (IR). The experimental impact of P-P bonding in structural polyphosphide anions is interpreted in the context of materials and bonding predictions from density functional theory (DFT). In support of the broader impacts of this project, Dr. Gillan is creating learning activities for undergraduate and K-12 students focused on industrially important materials and alternate energy processes, designing energy research opportunities for women and students from under-represented groups, and improving university laboratory safety culture at the University of Iowa.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.