Apr 12, 2024: Jonas Peters (CalTech)

Reductive PCET Mediators for Electro- and Photoelectrocatalysis Nitrogen reduction to ammonia is a requisite transformation for life and there is growing interest in developing sustainable technologies for ammonia synthesis using renewably sourced energy. Such approaches can lead to distributed on-demand fertilizer production and may enable ammonia to be used as a zero-carbon alternative fuel. Our group has had an ongoing interest in the study of well-defined synthetic catalysts that mediate nitrogen reduction (N2R) to ammonia (and hydrazine). We are especially interested in the operative mechanisms by which such catalysis occurs. Most recently, we have been pursuing the idea that proton-coupled electron transfer (PCET) pathways for N2R can be more thermally efficient than step-wise ET/PT pathways and have tested this hypothesis via the development of electrochemical PCET (ePCET) mediators that enable electrocatalytic N2R (and other reductive transformations with unsaturated substrates) to be driven at potentials sufficiently anodic that the competing hydrogen evolution reaction (HER) is mitigated. Relatedly, we are pursuing novel catalysts and conditions for photodriven N2R, and systems that enable (photo)electrochemical N2R. Here, visible light rather than temperature, pressure, or electrochemical potential, provides the primary driving force needed for catalytic ammonia generation. These same strategies offer attractive opportunities for reductions of unsaturated organic substrates.