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

Abstract

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.