Solar‐Driven Conversion of Nitrogen and Water to Solid Fertilizer in an Outdoor 1 m2 Panel Reactor

Harnessing solar energy to convert molecular N2 into nitrogen-rich chemicals (e.g., ammonia) provides a potential pathway for the manufacture of "solar fertilizers". However, the solar-to-ammonia (STA) efficiency of most solar fertilizer systems developed to date is less than 0.1%. Herein, an outstanding STA efficiency of ≈0.3% using a metallic molybdenum trioxide (metallic MoO3-x) photocatalyst under simulated-solar irradiation is reported, with localized surface plasmon resonance phenomena in the metallic MoO3-x photocatalyst enhancing both light utilization and N2 activation. The potential scalability of the photocatalytic technology is demonstrated in a 1 m2 panel reactor system, with a high STA efficiency and good stability demonstrated over 6 days of outdoor testing, yielding a solid (NH4)2SO4 product for easy collection. The as-designed square-meter outdoor reaction system facilitates the integration of solar fertilizer technology with existing agricultural infrastructure.