- Andrew J. Medford, Georgia Institute of Technology, Atlanta
Photocatalytic nitrogen fixation is a form of artificial photosynthesis capable of enabling distributed production of fixed nitrogen at near-ambient conditions from the nitrogen, water, and photons that are readily available from the environment. The process has been demonstrated over titania catalysts through both reductive and oxidative pathways, although the currently observed nitrogen fixation rates are too low to be practical for fertilizer synthesis and there is little fundamental understanding of the reaction mechanism or chemical phenomena that enable the process. Interestingly, the process occurs under environmental conditions and has been speculated to play a significant role in the global nitrogen cycle owing to the prevalence of TiO2 in naturally occurring sands and man-made pigments. Despite the wide-ranging potential impacts of this reaction, first demonstrated nearly 75 years ago, the process has received relatively little attention and has not been studied with modern techniques. This talk will briefly review the historical context and current progress toward photocatalytic nitrogen fixation, followed by a theoretical perspective into the thermodynamic driving forces and possible reaction mechanisms, with an emphasis on the potential for developing photoelectrochemical processes. The computational results will be complemented by recent experiments demonstrating the feasibility of the reaction.