Bioinspired Dual-Site Photocathode with Atomic Molybdenum and Alkynyl Networks for Scalable Solar Ammonia Synthesis

The Haber-Bosch process, while pivotal for global ammonia production, remains energy-intensive and environmentally unsustainable. Here, we report a nitrogenase-inspired photocathode (Mo₁/HsGDY@Cu₂O) that synergistically integrates light-harvesting Cu₂O nanowires, hydrogen-radical-generating alkynyl-rich graphdiyne (HsGDY), and atomically dispersed molybdenum sites for solar-driven nitrogen fixation. Mimicking the Fe/MoFe-cofactor collaboration in nitrogenase, the photocathode enables efficient N₂ adsorption at Mo₁ sites and hydrogen radical transfer from adjacent alkynyl groups, significantly lowering the energy barrier for N₂ hydrogenation. Under 10-sun illumination, the system achieves a record ammonia yield of 78.9 μg cm^-2 h^-1 with a Faradaic efficiency of 38.9% while maintaining 86% activity over 240 h. The ammonia solution directly enhances Epipremnum aureum root growth by 2.3-fold, demonstrating immediate agricultural utility. Combined with bias-free operation and scalable solar concentration, this work provides a practical blueprint for decarbonizing fertilizer production. Operando spectroscopy and DFT calculations further reveal that the dual-site synergy─Mo₁ for N₂ activation and alkynyl groups for H^• supply─drives the catalytic mechanism, offering a universal strategy for enzyme-inspired energy conversion systems.