(438a) Calcium Mediated Electrochemical Synthesis of Ammonia

The synthesis of green ammonia stands as a pivotal advancement towards fostering a sustainable and secure future, with applications ranging from agricultural fertilization to energy storage. To harness ammonia sustainably, innovative processes are imperative to mitigate the substantial carbon footprint and energy consumption inherent in conventional methods like the Haber-Bosch process. Electrochemical synthesis of ammonia emerges as a promising avenue, leveraging renewable resources for electricity consumption. Li mediated NH3 synthesis is a promising approach to make NH3 at ambient conditions and it has been widely investigated. This work explores the electrochemical calcium-mediated synthesis of ammonia (Ca-MAS) as an alternative approach. The process initiates with the electrodeposition of calcium metal on a Ni foam substrate, followed by nitridation, culminating in ammonia formation. While lithium-mediated synthesis has been extensively investigated, its reactivity poses safety concerns. Calcium, with a lower equilibrium potential for deposition and abundant availability compared to lithium, offers promising performance and economic viability. A comprehensive study examines various electrolyte compositions, including base electrolytes such as tetrahydrofuran (THF), propylene carbonate, acetonitrile, dimethoxy ethane, diethylene glycol dimethyl ether, and dimethyl sulfoxide (DMSO), considering factors such as volatility, conductivity, and stability. The effects of these compositions on performance metrics such as faradaic efficiency (FE) and current densities are analyzed. This work aims to achieve comparable yields and current efficiencies to lithium-mediated synthesis, thereby reducing associated costs and enhancing the environmental sustainability of ammonia production.