New Nonheme Iron Complexes for NOx Activation and Electrocatalysis

Dr. David P. Goldberg and Dr. V. Sara Thoi of Johns Hopkins University will investigate new iron-based chemical systems that could help address environmental pollution while advancing cleaner ways to make useful chemicals. The project will focus on nitrogen oxide compounds (NOx), pollutants that can build up in water because of fertilizer runoff and wastewater and may harm ecosystems and human health. Inspired by how nature uses iron-containing enzymes to transform these compounds, the team will develop new iron-based molecules that could convert NOx into ammonia, an important fertilizer ingredient and a promising carbon-free energy carrier. The work will support NSF priorities in Advanced Manufacturing by developing safer, more efficient chemical processes using earth-abundant materials under mild conditions, reducing energy use and waste compared to traditional industrial methods. It will also contribute to Biotechnology by increasing understanding of biologically important nitrogen transformations and iron-containing systems that living organisms use to process nitrogen compounds. Graduate and undergraduate students participating in the project will receive interdisciplinary training in chemical synthesis, catalysis, electrochemistry, and spectroscopy through collaborations with multiple U.S. research institutions. Outreach activities will focus on engaging Baltimore City high school students in hands-on chemistry experiences designed to increase interest and participation in STEM fields. The research will develop a new family of nonheme iron complexes designed to bind and activate nitrogen oxide species, including nitric oxide and nitrite. These compounds will be studied as synthetic analogs of biologically important iron-containing enzymes and as catalysts for the selective electrochemical conversion of nitrite to ammonia in water. The project will examine how the structure and electronic properties of the iron complexes influence nitrogen–oxygen bond cleavage, proton and electron transfer, and catalytic performance. Advanced spectroscopic, electrochemical, and spectro-electrochemical methods will be employed to identify short-lived reaction intermediates, including iron-bound nitroxyl species proposed to play key roles in nitrogen oxide reduction. Mechanistic insights gained from these studies would guide the rational design of efficient, earth-abundant catalysts for environmental nitrogen remediation and sustainable ammonia production. 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.