Intentional corrosion-induced reconstruction of defective NiFe layered double hydroxide boosts electrocatalytic nitrate reduction to ammonia

The electroreduction of nitrate to ammonia is particularly important in mitigating environmental pollution and obtaining value-added products. Although non-toxic and inexpensive iron-based materials are expected to be a promising catalyst for electrochemical nitrate reduction, ensuring their sustained high activity and inhibiting spontaneous corrosion requires the implementation of complex design. Here we report an economical self-corrosion approach that utilizes Ni2+ ions in wastewater to control the formation of NiFe layered double hydroxide active phase on iron surface, resulting in high nitrate conversion (97.2%) and ammonia selectivity (90.3%). Coupling nitrate reduction with acid absorption, the conversion from NO3− to (NH4)2SO4(s) for applications such as acting as fertilizer are achieved. This distinctive ‘waste-to-treasure’ perspective not only challenges the conventional belief that corrosion diminishes active phase but also notably improves catalytic efficiency while harnessing valuable resources from wastewater, offering a practical method for converting nitrate to useful ammonia products. Fe-based electrodes emerge as an effective and economical option to treat nitrate-laden wastewater. Whereas Fe cathode corrosion is commonly considered as an adverse factor for the electroreduction of nitrate to ammonia, intentional corrosion-induced surficial reconstruction has the potential to enhance catalytic performance.