The goal of this workshop is to identify and address the outstanding questions on the ambient associative N2 reduction reaction mechanism with a focus on coupling N2 reduction chemistry to sources of renewable electrons. This Workshop will focus on the mechanisms of coupling catalytic activation of dinitrogen (N2) to ammonia (NH3) and other reduced nitrogen products to renewable sources of electrons. NH3 is one of the most highly produced industrial chemicals and is used extensively in the agriculture industry, either directly or as the precursor for other N-based fertilizers. NH3 is also being evaluated as a potential alternative fuel and energy carrier in a future renewable energy economy. A major challenge in producing NH3 and other reduced nitrogen products lies in activating the highly stable N2 triple bond. Activation can be achieved via two reaction mechanisms: dissociative or associative. The Haber-Bosch process, which is the dominant industrial NH3 production process, proceeds by the dissociative mechanism, using thermochemical activation of the N2 triple bond and N-hydrogenation by H2 to form NH3. This is a very energy intensive and CO2 producing process, estimated to account for 1-2% of annual global energy use. Alternatively, the associative mechanism activates N2 by weakening of the triple bond and subsequent reduction involving hydride intermediates. Hydride formation requires a series of electron/proton steps that are synchronized with N2 activation for reduction to two molecules of NH3. The associative mechanism is how nature reduces N2 to ammonia by nitrogenase enzymes without the need for thermal activation. One essential challenge to understanding this mechanism is to understand how nitrogenase couples hydride reactive chemistry to the activation and reduction of N2 while minimizing sacrificial formation of H2 gas. Further, the mechanisms of non-biological catalysts are not sufficiently understood to instill controlled reactivity and selectivity. This Workshop will discuss mechanistic insight for N2 reduction, advancing more efficient and less environmentally impactful production technologies for ammonia and other reduced nitrogen products.
Workshop attendees will have a research focus on the mechanistic aspects of the generation of NH3 and other reduced nitrogen products in biological, biomimetic, molecular, and material catalysis that utilize the associative mechanism. The workshop will compare experimental and theoretical reaction pathways in both the gas and solution phase, with particular emphasis on electrochemistry, photoelectrochemistry, and photochemistry processes. Assembling attendees across this diverse range of backgrounds will provide a productive, interactive session where lessons learned and best practices can be transmitted across the research disciplines.