Rational design of iron single-atom catalysts for electrochemical nitrate reduction to produce ammonia

Abstract

Ammonia (NH3) is the second-most produced chemical with broad applications and vital for the chemical industry. However, the current Haber–Bosch synthesis is problematic with high energy consumption and carbon footprints. Electrochemical nitrate reduction (NO3RR) to produce NH3 is a green, low-carbon and efficient alternative route to simultaneously benefit wastewater treatment, mild NH3 production and global warming mitigation. Compared to noble metal catalysts or the nanosized counterparts, iron single-atom catalysts (Fe SACs) boast unique advantages to promote the NO3RR because of the exceptional selectivity, inexpensiveness, high efficiency and good durability. Due to the rapid development of the emerging field, a timely Perspective with an emphasis on the recent advances in Fe SACs-catalyzed NO3RR is currently lacking. The Perspective aims to give an account of the up-to-date progresses on Fe SACs-promoted NO3RR for NH3 production. The catalyst design, characterizations, mechanism studies, etc. will be illustrated, and lastly the challenges and outlook will be discussed to provide insights for future studies.

Charge Redistribution in High-Entropy Perovskite Oxide Porous Nanotubes Boosts Nitrate Electroreduction to Ammonia

“…Interestingly, the obtained FE NHd 3 and yield rate NHd 3 on LSNCMFC PNTs are clearly greater than those of the electrocatalysts. To confirm that the obtained NH 3 was produced from the electrocatalytic reduction of NO 3 − , the electrolyte with an equimolar concentration of isotope 15 NO 3 − was used and tested at the potential of −0.9 V RHE and formation of NH 3 was confirmed Furthermore, Kelvin probe force microscopy (KPFM) was conducted to investigate the surface potential of LN PNTs and LSNCMFC PNTs. The potential distributions at the LN PNT and LSNCMFC PNT surface are shown in Figure 5a with their corresponding topography images.…”

“…As a versatile compound, ammonia (NH 3 ) has a vital impact in fields such as fertilizers, chemicals, or fuels. , Over the past century, the Haber–Bosch process has been the main industrial synthesis process for the preparation of NH 3 , which not only generated huge amounts of carbon dioxide emissions but also requires a large infrastructure and energy consumption. , Compared with the NN bond of N 2 , the energy required to dissociate the NO bond of nitrate (NO 3 – ) is much lower. − As of the present, due to the extensive use of various N-containing products, the content of NO 3 – in the wastewater discharged is increasing. , Therefore, recently, converting NO 3 – into NH 3 through renewable power is a promising alternative to the Haber–Bosch process, which solves the energy problem while reducing the environmental impact of NO 3 – in wastewater. − Since the electrochemical NO 3 – reduction reaction (NO 3 RR) is a complex multielectron transfer process involving the valence state from +5 to −3, accompanied by a severe hydrogen evolution reaction (HER), the electroreduction of NO 3 – to NH 3 has low yield, selectivity limiting the development of the NO 3 RR. Hence, there is an urgent need to develop efficient and highly selective electrocatalysts for the NO 3 RR.…”

“…nuclear magnetic resonance ( 1 H NMR) spectroscopy. The 1 H NMR spectrum of the electrolyte with K 15 NO 3 as the reactant showed a typical15 NH 4 + double peak (Figure4d), indicating that the NH 3 (NH 4 + ) produced is exclusively from the added NO 3 − . Cycling stability experiments were carried out in multiple turns to evaluate the catalytic stability of the LSNCMFC PNTs.…”

Enhancing Efficiency of Nitrate Reduction to Ammonia by Fe and Co Nanoparticles Based Bimetallic Electrocatalyst

“…Pure iron has low stability in aqueous media due to corrosion. Nanocomposites and bimetallic catalysts, as well as reasonable design of iron single-atom catalysts (Fe SAC) [26] can be a solution to this problem. For Fe SAC, the maximum FE was ~75% at -0.66 V with the highest NH3 production rate of 0.46 mmol/h/cm 2 at -0.85 V. The rate of ammonia production on Fe SAC is not high enough, so the rational choice of a carbon substrate, increase of the Fe SAC content on the substrate, introduction of components preventing aggregation of Fe SAC particles are important.…”