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