Nitrate Reduction by NiFe-LDH/CeO₂: Understanding the Synergistic Effect between Dual-Metal Sites and Dual Adsorption

Abstract

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 pseudofirst-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.

Bimetallic PdCo and PdNi Nanoparticles Supported on Covalent Organic Frameworks as Catalysts for the Hydrogenation of 4-Nitrophenol

“…From the Ni 2p XPS spectrum of PdNi/COFs-1 (Figure E), it reveals that Ni mainly exists in two forms, Ni(OH) 2 and NiOOH, with B.E. of 855.9 and 857.6 eV, respectively . The featured peak of Pd(0) in the multimetallic catalysts is with a shift to low B.E.…”

Polyoxometalate-Intercalated Tremella-Like CoNi-LDH Nanocomposites for Electrocatalytic Nitrite–Ammonia Conversion

“…Meanwhile, the introduction of P 8 W 48 Lewis acid sites further promotes the adsorption of NO 2 – . The CoNi-LDH phase possesses an extremely low energy barrier in the protonation reaction (the rate-determining step), while the P 8 W 48 species can serve as an electron-transfer carrier to further accelerate the reaction kinetics, , which together promote the six-electron reduction process of absorbed NO 2 – . Meanwhile, the insertion of the P 8 W 48 polyanion into the interlayer of CoNi-LDH endows this composite with a large contact area between P 8 W 48 and CoNi-LDH, which can maximize the performance improvement of the P 8 W 48 /CoNi-LDH composite.…”