(543g) Enhanced Electrochemical Ammonia Production Via Peptide-Bound Metal

Authors: 
Loney, C., Case Western Reserve University
Renner, J. N., Case Western Reserve University
Greenlee, L. F., University of Arkansas
Janik, M. J., Pennsylvania State University
Suttmiller, D., University of Arkansas
Approximately half of the people on the planet are alive because of synthetically produced ammonia. However, due to the fossil fuels used in the current ammonia synthesis process, its production contributes a significant amount to the world’s greenhouse gas emissions. Haber-Bosch synthesis, which is the most widely used method of producing synthetic ammonia today, requires high temperatures (400-500 °C) and pressures (150-200 atm). This process is also energy intensive, consuming approximately 2% of worldwide energy. By taking an electrochemically-based approach to ammonia synthesis, those harsh conditions and emissions can be eliminated. However, current catalysts are not selective for the desired reaction.

We hypothesize that 3D surface modifications can be utilized to overcome these selective limitations and create catalysts which mimic the selectivity of the nitrogenase enzyme: an enzyme that catalyzes the reduction of nitrogen to ammonia at mild temperatures and pressures. Therefore, in this study, we show that a peptide sequence, when bound to iron(iii) oxide metal nanoparticles, facilitates electrochemical ammonia with relatively high efficiency. These recent results were obtained in an alkaline, solid-state electrochemical cell, yielding an electrochemical ammonia production rate and faradaic efficiency that is >10x higher than the catalyst without bound peptide. These results are corroborated in an alkaline liquid-based cell.

This discussion covers the characterization of the peptide and its interactions with iron(iii) oxide. The goal of this study is to elucidate the peptide’s effects on material properties and how they might lead to increased ammonia production. Techniques and instrumentations used to investigate our system involve a quartz crystal microbalance with dissipation (QCM-D) with humidity and electrochemistry modules, x-ray photoelectron spectroscopy (XPS), BET gas adsorption, circular dichroism (CD), and various electrochemical techniques. The insights revealed in this work will eventually be used to direct material optimization for efficient electrochemical ammonia production.