High-productivity electrosynthesis of ammonia from dinitrogen

The so-called lithium redox-mediated nitrogen reduction reaction presents the only known process enabling genuine electrochemical conversion of N2 to ammonia. Notwithstanding the rapidly increasing investigative efforts, the commonly reported performances of the Li-mediated N2 electroreduction, viz. yield rate, current-to-ammonia (faradaic) efficiency and durability in operation, still pertain to the domain of academic research rather than practical development. Our most recent work focused on redesigning the key components of the electrolytic N2 reduction cell enabled breakthroughs in all the key metrics of the process. Specifically, we have introduced a stable proton shuttle based on the phosphonium cation that delivers protons to…


Alternatives to Ammonia Synthesis: An Electrochemical Haber-Bosch Process

Several alternatives to the existing process for ammonia synthesis, the Haber-Bosch Process, have been proposed in the past two decades, including the electrochemical synthesis in aqueous, molten salt or solid electrolyte cells. The present work reviews results of recent efforts (last 3 years) for the electrochemical synthesis of ammonia. An Electrochemical Haber-Bosch Process is also demonstrated. The proposed BaZrO3 – based protonic ceramic membrane reactor combines hydrogen production via the reactions of methane steam reforming and water-gas shift at the anode (Ni-composite) with ammonia synthesis from N 2 and protons (H + ) at the cathode (VN-Fe). Hydrogen extraction from…


Electrification of Ammonia Synthesis

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…


Whither Aqueous Electro-reduction of Nitrogen to Ammonia?

Electrochemical reduction of N 2 (NRR) is widely recognised as an alternative to the traditional Haber-Bosch production process for ammonia. The high-energy efficiency, low-cost variant of this process involves an aqueous electrolyte and there is now a substantial literature on this topic. However, though the challenges of NRR experiments have become better understood, the reported rates in these aqueous solution studies are often too low to be convincing that reduction of the highly unreactive N 2 molecule has actually been achieved. Unfortunately, there are many possible impurity sources that can interfere with robust measurements. In this presentation we will discuss…


Monash team publishes Ammonia Economy Roadmap

Earlier this month, Doug MacFarlane and his team of researchers at Monash University published A Roadmap to the Ammonia Economy in the journal Joule. The paper charts an evolution of ammonia synthesis “through multiple generations of technology development and scale-up.” It provides a clear assessment of “the increasingly diverse range of applications of ammonia as a fuel that is emerging,” and concludes with perspectives on the “broader scale sustainability of an ammonia economy,” with emphasis on the Nitrogen Cycle. The Roadmap is brilliant in its simple distillation of complex and competing technology developments across decades. It assesses the sustainability and scalability of three generations of ammonia synthesis technologies. Put simply, Gen1 is blue ammonia, Gen2 is green ammonia, and Gen3 is electrochemical ammonia. It also outlines the amount of research and development required before each could be broadly adopted (“commercial readiness”). The paper thus provides vital clarity on the role that each generation of technology could play in the energy transition, and the timing at which it could make its impact.


Mechanistic Insights into Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride Nanoparticles

Renewable production of ammonia, a building block for most fertilizers, via the electrochemical nitrogen reduction reaction (ENRR) is desirable; however, a selective electrocatalyst is lacking. Here we show that vanadium nitride (VN) nanoparticles are active, selective, and stable ENRR catalysts. ENRR with 15N2 as the feed produces both 14NH3 and 15NH3, which indicates that the reaction follows a Mars–van Krevelen mechanism. Ex situ and operando characterizations indicate that VN0.7O0.45 is the active phase for ENRR and the conversion of VN0.7O0.45 to the VN phase leads to catalyst deactivation. Quantitative isotopic labeling results identify the amounts of two different types of…