Solar-Driven Ammonia Synthesis From Nitrate Reduction Paired With CO₂ Capture for Sustainable Agriculture via a...

The transition to sustainable agriculture requires technologies that simultaneously enhance crop yields and reduce environmental impacts. Solar-driven nitrate valorization, when coupled with CO₂ capture from industrial flue gas, presents a promising dual strategy for producing high-value fertilizers while mitigating carbon emissions. However, its practical implementation is hindered by two interrelated challenges: (i) the intermittent nature of solar irradiation and (ii) the competitive hydrogen evolution reaction (HER), which severely compromises Faradaic efficiency (FE) of desired nitrogenous products. Here, we address these challenges by designing a heterogeneous CuPd electrocatalyst featuring an amorphous/crystalline heterojunction. This catalyst suppresses HER across a broad potential window (-0.4 to -1.4 V), maintaining >80% FE(ammonia) for >100 h. The catalytic robustness enables stable solar-powered electrolysis even under low irradiation (0.4 sun), achieving >70% FE(ammonia) and 6% solar-to-fuel conversion efficiency, while catholyte simultaneously captures CO₂ at a rate of 6-20 mg h^-1. Techno-economic analysis demonstrates cost competitiveness against biological counterparts. When applied to plant cultivation, this artificial photosynthesis system boosts solar-to-biomass conversion efficiency by 3.5-fold compared to natural photosynthesis. By unifying solar energy harvesting, waste nitrate reduction, and carbon sequestration, our work provides a scalable blueprint for a closed-loop agrochemical ecosystem and advanced catalyst design for intermittent renewable-powered electrosynthesis.