Challenges and Opportunities for Renewable Ammonia Production via Plasmon‐Assisted Photocatalysis

Despite its severe operating conditions, associated energy consumption, and environmental concerns, the manufacture of nitrogen‐rich fertilizers still relies heavily on producing ammonia in centralized chemical plants via the Haber–Bosch process. A distributed and more sustainable scheme considers the on‐site production of carbon‐neutral fertilizers at ambient conditions in photocatalytic reactors powered by sunlight. Among the different strategies proposed to boost the nitrogen reduction ability of conventional catalysts, the incorporation of plasmonic nanomaterials is gaining widespread interest owing to their unique optical tunability and their potential to improve the efficiency and selectivity of many chemical transformations. This Perspective examines the state‐of‐the‐art for the nitrogen reduction reaction via plasmon‐driven photocatalysis and discusses design principles for advancing it. The different physical mechanisms underlying the operation of plasmonic materials in a catalytic setting, and the dimensions along which the catalysts can be tuned to harness them are detailed. Paths to overcome current frontiers in the field, including design strategies of plasmonic photocatalysts, the development of complementary characterization techniques, the standardization of the reaction conditions and ammonia quantification methods, and the possibilities offered by theoretical methods to drive material discovery, identifying fundamental bottlenecks, and proposing directions for the advancement of this emerging field are outlined. Plasmon‐based photocatalytic nitrogen reduction has been recently proposed as a potential alternative to the Haber–Bosch process for the sustainable manufacture of ammonia. This perspective lays down a number of experimental and theoretical practices to assist the design of plasmonic photocatalysts towards this goal, paying special attention to current pitfalls and limitations that hinder further developments in the field.