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Near-term prospects for decarbonized ammonia synthesis rely on conventional thermochemical Haber Bosch coupled to either electrochemical hydrogen production or methods of mitigating carbon emissions, such as carbon capture and storage. Thermochemical Haber Bosch requires high temperatures to achieve significant rates of ammonia synthesis and high pressures in order to achieve reasonable conversions of nitrogen and hydrogen to ammonia. Next-generation electrically-driven routes raise the prospect of using voltage in the place of temperature and pressure – an ambient pressure and room temperature route through which renewable electricity can be used to convert nitrogen and hydrogen to ammonia.
Electrically-driven routes for nitrogen fixation remain relatively immature and there are significant technical challenges to be overcome in order to achieve high rates and energy efficiencies. Our lab has developed a semi-batch lithium-mediated approach to ammonia synthesis, achieving the highest rates of nitrogen fixation at ambient conditions. Specifically, we have developed a gas diffusion electrode technology which allows for significantly improved rates of nitrogen fixation with suppression of competing hydrogen evolution. We will discuss these technical advances in the context of remaining challenges for future methods of electrically-driven ammonia synthesis.