Understanding and tuning the electrohydrogenation mechanisms for ambient nitrogen fixation

This project is funded through an NSF CAREER Award (CHE #1943732, July 1, 2020- June 30, 2025).

As the industrial production of chemicals relies on the consumption of fossil fuels it is critical to develop technologies for their sustainable production. Ammonia is a key ingredient in agricultural fertilizers. Ammonia manufacture consumes 3-5% of the world’s natural gas output and generates 1-2% of global carbon dioxide emissions. An alternative approach is to make ammonia from nitrogen and water using electricity generated from renewable sources such as solar or wind. To date, however, this process suffers from low yields and slow reactions. In this project, Dr. Xiaofeng Feng of the University of Central Florida is developing fundamental understanding of the reaction chemistry and improving the electrocatalysts needed to improve yields and reaction rates. The science and the methods developed in this project will help advance the development of ammonia electrosynthesis technologies that will benefit global sustainability while maintaining or improving current levels of food production. Dr. Feng and his team are increasing the awareness and knowledge of renewable energy technologies for students at the university and K-12 levels through interdisciplinary education and outreach activities. Dr. Feng is developing interdisciplinary education modules and outreach activities with a focus on universities and high schools with high minority enrollment.

With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Xiaofeng Feng of the University of Central Florida is investigating the fundamental mechanisms for the electrochemical reduction of nitrogen to ammonia. The research group is also developing efficient electrocatalysts for the process. To date, the nitrogen reduction reaction (NRR) suffers from low reaction rates and selectivity due to the competing hydrogen evolution reaction (HER) in aqueous electrolyte. This project is elucidating the competition between the NRR and the HER as well as the impact of competition on the electrokinetics of NRR. Strategies are developed to control the electrode-electrolyte interface so that the competition from the HER can be mitigated to improve the NRR activity and selectivity. Also under investigation are the pathways for the hydrogenation of nitrogen molecules adsorbed on electrocatalysts, which are used to further guide the development of metal-based catalysts for NRR. Both ex situ and operando characterizations are performed to confirm the atomic structure and chemical state of the developed catalysts, establishing structure-activity relationships. The understandings and catalysts developed in this project can improve the production rates and selectivity of ammonia electrosynthesis, which will advance the development of renewable energy technologies for a sustainable future.