Nitrate Reduction by NiFe-LDH/CeO 2 : Understanding the Synergistic Effect between Dual-Metal Sites and Dual Adsorption.

Electrocatalytic nitrate reduction reaction (EC-NITRR) shows a significant advantage for green reuse of the nitrate (NO 3 - ) pollutant. However, the slow diffusion reaction limits the reaction rate in practical EC-NITRR, causing an unsatisfactory ammonia (NH 3 ) yield. In this work, a multifunctional NiFe-LDH/CeO 2 with the dual adsorption effect (physisorption and chemisorption) and dual-metal sites (Ce 3+ and Fe 2+ ) was fabricated by the electrodeposition method. NiFe-LDH/CeO 2 performed an expected ability of enrichment for NO 3 - through the pseudo-first-order and pseudo-second-order kinetic models, and the polymetallic structure provided abundant sites for effective reaction of NO 3 - . At-0.6 V vs RHE, the ammonia (NH 3 ) yield of NiFe-LDH/CeO 2 reached 335.3 μg h -1 cm -2 and the selectivity of NH 3 was 24.2 times that of NO 2 - . The nitrogen source of NH 3 was confirmed by 15 NO 3 - isotopic labeling. Therefore, this work achieved the recycling of the NO 3 - pollutant by synergy of enrichment and catalysis, providing an alternative approach for the recovery of NO 3 - from wastewater.