CRII: OAC: Extrapolative Exploration of High-Entropy Alloys for Optimized Nitrate Adsorption During Nitrate Reduction to Ammonia

Electrochemical reduction of nitrate to ammonia is an emerging process with significant importance in alleviating nitrate contamination in water and producing ammonia with less energy. The key to effective nitrate reduction lies in designing stable, efficient, and highly selective catalysts. Recently, high entropy alloys have been attracting growing attention for catalytic systems thanks to their remarkable stability in diverse environments, and tunable surface microstructures that allow the fine modulation of the adsorption, activation, and desorption of reaction intermediates. However, the investigation of using high entropy alloys for the electrocatalytic nitrate reduction to ammonia is still in an early stage, and this project aims to answer the question of how to identify the ideal compositional configurations of high entropy alloys for nitrate adsorption with optimal binding strength. The research activities contribute to the enrichment of campus engineering education in various disciplines, such as density functional theory calculations, machine learning, wastewater treatment, electrochemistry, and nanotechnology. This project also provides a platform for outreach activities, where students can perform hands-on experiments and develop their interests in science and engineering. This project aims to design a computational framework that integrates density functional theory calculations and machine learning algorithms to effectively explore the multidimensional space of high entropy alloys and actively identify optimal structural compositions for nitrate adsorption with desired binding strength, such that complex nitrate reduction reactions can be completed more effectively and selectively to produce ammonia sustainably. The research outcome advances the fundamental understanding of nitrate reduction to ammonia using high entropy alloys from several different aspects, such as (1) the interactions of nitrate molecules with diverse surface microstructures and (2) the relationships among structure, property, and catalytic performance, which facilitate the catalyst design for the industrial implementation of nitrate conversion to ammonia through electrochemical reduction, and alleviate the energy consumption for both the wastewater treatment and ammonia production sectors. 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.