Electrochemical strategy based on iron oxide promotes in-situ nitrate reduction to ammonium for nitrogen uptake by...

Developing practical and cost-effective technologies to improve nitrate utilization efficiency is critical for reducing nitrogen load in paddy fields. Given the ammonium preference of rice, the reduction of nitrate to ammonium promotes nitrogen uptake, thereby enhancing crop yield. However, practical applications often suffer from low selectivity when treating nitrate in complex agricultural drainage water. Building on the "treatment-as-fertilization" principle established with single-atom catalysts, this study presents a scalable strategy for nitrate-to-ammonium conversion using earth-abundant α-FeOOH. Through interfacial engineering with the surfactant cetyltrimethylammonium bromide (CTAB), the electrocatalytic pathway was effectively modulated to achieve a 92.1% ammonium selectivity in real agricultural drainage. When integrated into a solar-powered plant-electrochemical system (Plant-ECS), this "pollutant-to-fertilizer" loop resulted in a 47.5% increase in nitrogen uptake and a 21.7% biomass enhancement, as confirmed by ¹ ⁵N isotope tracing. These findings demonstrate a scalable approach to sustainable nutrient management, proving that high-selectivity nitrate valorization is achievable with cost-effective materials, thus offering a feasible ecological engineering blueprint. SYNOPSIS: An ecological engineering approach that closes the agricultural nitrogen loop by upcycling nitrate pollution into a bioavailable fertilizer.