Pulsed electrocatalysis on iron-decorated copper foam enables efficient and selective ammonia synthesis from low-concentration nitrate

Electrocatalytic nitrate reduction to ammonia (NRA) is a promising technology for water remediation, but its application to environmentally relevant low concentrations (< 20 ppm) is severely hampered by mass transport limitations and low selectivity. This study introduces a novel strategy combining pulse electrocatalysis with a tailor-made iron-decorated copper foam (Fe@CF) electrode to overcome these challenges. When applied to 20 ppm nitrate solution, the system under optimized pulse conditions demonstrated a remarkable performance, achieving 99 % nitrate removal efficiency and 96 % ammonia selectivity within 150 min, resulting in an ammonia yield of 93 μg·h⁻¹ ·cm⁻². This represents a significant enhancement over conventional direct current (DC) electrolysis, which suffered from substantial nitrite accumulation. Characterization confirms that Fe nanoparticles, acting as tandem catalytic sites, were uniformly deposited on the porous Cu foam. The superior performance is attributed to a dual-enhancement mechanism: (1) the pulsed potential effectively alleviates mass transport limitations by facilitating reactant replenishment and product desorption, and (2) the synergistic effect between Cu and Fe sites promotes the rapid conversion of nitrite intermediates to ammonia. This work highlights that integrating advanced electrode design with pulse electrocatalysis is a potent approach for efficient and selective nitrogen recovery from dilute nitrate-contaminated water.