Photoexcitation Altered Reaction Pathway Greatly Facilitate Ammonia Synthesis Over Isolated Ru Sites

Abstract Ammonia, poised as a carbon‐neutral energy carrier, holds immense promise in reshaping the future energy landscape. Despite the enduring importance of the Haber–Bosch process in ammonia production, its substantial carbon emissions and energy demands necessitate more sustainable pathways. Here, an advanced ammonia synthesis route, enhanced by photoexcitation is demonstrated, which fundamentally modifies the activation pathways of N 2 molecules. This alteration significantly lowers the reaction activation energy, resulting in remarkably improved reaction efficiency. The impact of light excitation culminates in an unprecedented ammonia synthesis rate of 18 mmol g −1 h −1 , surpassing the traditional thermal catalytic process by 2.57‐fold. More importantly, light assistance reduces the thermal energy input by ≈16%, making it comparable to thermal catalysis while substantially improving energy utilization. This work introduces a greener strategy for ammonia synthesis, pushing the century‐old fossil‐fueled Haber–Bosch process to a new frontier.