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Ammonia-oxidizing archaea (AOA) are among the most ubiquitous and abundant archaea on Earth, widely distributed in marine, terrestrial, and geothermal ecosystems. However, the genomic diversity, biogeography, and evolutionary process of AOA populations in subsurface environments are vastly understudied compared to those in marine and soil systems. Here, we report a novel AOA order Candidatus (Ca.) Nitrosomirales which forms a sister lineage to the thermophilic Ca. Nitrosocaldales. Metagenomic and 16S rRNA gene-read mapping demonstrates the abundant presence of Nitrosomirales AOA in various groundwater environments and their widespread distribution across a range of geothermal, terrestrial, and marine habitats. Terrestrial Nitrosomirales AOA show the genetic capacity of using formate as a source of reductant and using nitrate as an alternative electron acceptor. Nitrosomirales AOA appear to have acquired key metabolic genes and operons from other mesophilic populations via horizontal gene transfer, including genes encoding urease, nitrite reductase, and V-type ATPase. The additional metabolic versatility conferred by acquired functions may have facilitated their radiation into a variety of subsurface, marine, and soil environments. We also provide evidence that each of the four AOA orders spans both marine and terrestrial habitats, which suggests a more complex evolutionary history for major AOA lineages than previously proposed. Together, these findings establish a robust phylogenomic framework of AOA and provide new insights into the ecology and adaptation of this globally abundant functional guild.

Electrochemical reduction of nitrate (NO3RR) holds great promise for environmentally friendly ammonia production. Tandem catalysis is a promising strategy for boosting the NO3RR and inhibiting side effects, but it is still challenged by lacking well‐designed catalysts to drive this catalytic process. Herein, the study develops the CuCo branched nanowires (CuCo NW) catalyst, which efficiently converts NO3− to NH3 on Co (111) and Cu (111) crystal facets through a tandem catalysis mechanism. The in situ grown CuCo NW on Cu foam demonstrates a remarkable Faraday efficiency of 90.3% at 1.0 A cm−2 and maintains stable operation for 200 h at 100 and 200 mA cm−2 in a flow reactor. Density functional theory calculations suggest that the initial absorption and subsequent deoxygenation of *NO3 on Co (111) leading to the formation of *NO2, followed by its transfer to Cu (111) and further conversion to *NH3, establish an optimal pathway by managing rate‐determining steps on individual surfaces for NO3RR. To showcase the practical application of the catalyst, the study further develops a scaling‐up prototype reactor for continuous ammonia production, realizing the gram‐level yield rate of 1474.09 mg h−1 and Faraday efficiency of 91.26% at practical‐level 20.0 A. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a promising pathway for ammonia synthesis. The interfacial electronic interactions (IEIs) can regulate the physicochemical capabilities of catalysts in electrochemical applications, while the impact of IEIs on electrocatalytic NRA remains largely unexplored in current literature. In this study, the high‐efficiency electrode Ag‐modified Co3O4 (Ag1.5Co/CC) is prepared for NRA in neutral media, exhibiting an impressive nitrate conversion rate of 96.86 %, ammonia Faradaic efficiency of 96.11 %, and ammonia selectivity of ~100 %. Notably, the intrinsic activity of Ag1.5Co/CC is ~81 times that of Ag nanoparticles (Ag/CC). Multiple characterizations and theoretical computations confirm the presence of IEIs between Ag and Co3O4, which stabilize the CoO6 octahedrons within Co3O4 and significantly promote the adsorption of reactants (NO3−) as well as intermediates (NO2− and NO), while suppressing the Heyrovsky step, thereby improving nitrate electroreduction efficiency. Furthermore, our findings reveal a synergistic effect between different active sites that enables tandem catalysis for NRA: NO3− reduction to NO2− predominantly occurs at Ag sites while NO2− tends to hydrogenate to ammonia at Co sites. This study offers valuable insights for the development of high‐performance NRA electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a promising pathway for ammonia synthesis. The interfacial electronic interactions (IEIs) can regulate the physicochemical capabilities of catalysts in electrochemical applications, while the impact of IEIs on electrocatalytic NRA remains largely unexplored in current literature. In this study, the high‐efficiency electrode Ag‐modified Co3O4 (Ag1.5Co/CC) is prepared for NRA in neutral media, exhibiting an impressive nitrate conversion rate of 96.86 %, ammonia Faradaic efficiency of 96.11 %, and ammonia selectivity of ~100 %. Notably, the intrinsic activity of Ag1.5Co/CC is ~81 times that of Ag nanoparticles (Ag/CC). Multiple characterizations and theoretical computations confirm the presence of IEIs between Ag and Co3O4, which stabilize the CoO6 octahedrons within Co3O4 and significantly promote the adsorption of reactants (NO3−) as well as intermediates (NO2− and NO), while suppressing the Heyrovsky step, thereby improving nitrate electroreduction efficiency. Furthermore, our findings reveal a synergistic effect between different active sites that enables tandem catalysis for NRA: NO3− reduction to NO2− predominantly occurs at Ag sites while NO2− tends to hydrogenate to ammonia at Co sites. This study offers valuable insights for the development of high‐performance NRA electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a promising pathway for ammonia synthesis. The interfacial electronic interactions (IEIs) can regulate the physicochemical capabilities of catalysts in electrochemical applications, while the impact of IEIs on electrocatalytic NRA remains largely unexplored in current literature. In this study, the high‐efficiency electrode Ag‐modified Co3O4 (Ag1.5Co/CC) is prepared for NRA in neutral media, exhibiting an impressive nitrate conversion rate of 96.86 %, ammonia Faradaic efficiency of 96.11 %, and ammonia selectivity of ~100 %. Notably, the intrinsic activity of Ag1.5Co/CC is ~81 times that of Ag nanoparticles (Ag/CC). Multiple characterizations and theoretical computations confirm the presence of IEIs between Ag and Co3O4, which stabilize the CoO6 octahedrons within Co3O4 and significantly promote the adsorption of reactants (NO3−) as well as intermediates (NO2− and NO), while suppressing the Heyrovsky step, thereby improving nitrate electroreduction efficiency. Furthermore, our findings reveal a synergistic effect between different active sites that enables tandem catalysis for NRA: NO3− reduction to NO2− predominantly occurs at Ag sites while NO2− tends to hydrogenate to ammonia at Co sites. This study offers valuable insights for the development of high‐performance NRA electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate (NO3−) reduction to ammonia (NRA) offers a promising pathway for ammonia synthesis. The interfacial electronic interactions (IEIs) can regulate the physicochemical capabilities of catalysts in electrochemical applications, while the impact of IEIs on electrocatalytic NRA remains largely unexplored in current literature. In this study, the high‐efficiency electrode Ag‐modified Co3O4 (Ag1.5Co/CC) is prepared for NRA in neutral media, exhibiting an impressive nitrate conversion rate of 96.86 %, ammonia Faradaic efficiency of 96.11 %, and ammonia selectivity of ~100 %. Notably, the intrinsic activity of Ag1.5Co/CC is ~81 times that of Ag nanoparticles (Ag/CC). Multiple characterizations and theoretical computations confirm the presence of IEIs between Ag and Co3O4, which stabilize the CoO6 octahedrons within Co3O4 and significantly promote the adsorption of reactants (NO3−) as well as intermediates (NO2− and NO), while suppressing the Heyrovsky step, thereby improving nitrate electroreduction efficiency. Furthermore, our findings reveal a synergistic effect between different active sites that enables tandem catalysis for NRA: NO3− reduction to NO2− predominantly occurs at Ag sites while NO2− tends to hydrogenate to ammonia at Co sites. This study offers valuable insights for the development of high‐performance NRA electrocatalysts. [ABSTRACT FROM AUTHOR]

Ammonia is an important raw material for agricultural production, playing a key role in global food production. However, conventional ammonia synthesis resulted in extensive greenhouse gas emissions and huge energy consumption. Recently, researchers have proposed electrocatalytic reverse artificial nitrogen cycle (eRANC) routes to circumvent these issues, which can be driven by electrocatalysis and sustainable electricity. Here, a theoretical and computational perspective on the challenges and opportunities with the comparison with experimental results: electrochemical reduction of nitrate (eNO3RR) and nitrite (eNO2RR), electrochemical reduction of nitric oxide (eNORR) combined with oxidative nitrogen fixation are presented. By comparison, the N2→NO→NH3 route is proposed as the most promising in case the NO solubility can be solved well in reactor design. Its high efficiency of ammonia production is demonstrated. Instead, the eNO3RR can be another choice because it is non‐toxic and the solid‐liquid interface is usually efficient for electrochemical reactions, while its low selectivity at low overpotentials is an issue. These fundamentals highlight the potential and key factors of eRANC as an efficient and sustainable route for ammonia production. [ABSTRACT FROM AUTHOR]

[Display omitted] Conversion of NO 3 − to NH 3 proceeds stepwise in natural system under two different enzymes involving intermediate NO 2 −. Artificial electro-driven NO 3 − reduction also faces the obstacle of low faradaic efficiency due to insufficient utilization of this intermediate. Herein, we demonstrate a bimetallic COF-based electrocatalyst for the cascade catalysis of NO 3 −-to-NO 2 −-to-NH 3 for the first time. TpBpy-Cu 2 Co 4 exhibits a significantly improved performance, with an enhancement factor of 1.4–2 compared to monometallic TpBpy-M. The NH 3 yield rate achieves 25.6 mg h−1 mg cat. −1 at −0.55 V vs RHE over TpBpy-Cu 2 Co 4 , together with excellent faradaic efficiency (93.4 %). This achievement demonstrates cascade catalysis between Co and Cu units, and their distinct roles are investigated through electrochemical experiments and theory calculations. In electrocatalytic process, Cu site facilities *NO 3 -to-*NO 3 H step, while the Co site significantly decreases the energy barrier of *NHOH-to-*NH. The present work provides a valuable inspiration in designing efficient catalysts for cascade reaction. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO3−RR) is an important route for sustainable NH3 synthesis and environmental remediation. Metal–organic frameworks (MOFs) are one family of promising NO3−RR electrocatalysts, however, there is plenty of room to improve in their performance, calling for new design principles. Herein, a MOF‐on‐MOF heterostructured electrocatalyst with interfacial dual active sites and build‐in electric field is fabricated for efficient NO3−RR to NH3 production. By growing Co‐HHTP (HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene) nanorods on Ni‐BDC (BDC=1,4‐benzenedicarboxylate) nanosheets, experimental and theoretical investigations demonstrate the formation of Ni−O−Co bonds at the interface of MOF‐on‐MOF heterostructure, leading to dual active sites tailed for NO3−RR. The Ni sites facilitate the adsorption and activation of NO3−, while the Co sites boost the H2O decomposition to supply active hydrogen (Hads) for N‐containing intermediates hydrogenation on adjacent Ni sites, cooperatively reducing the energy barriers of NO3−RR process. Together with the accelerated electron transfer enabled by built‐in electric field, remarkable NO3−RR performance is achieved with an NH3 yield rate of 11.46 mg h−1 cm−2 and a Faradaic efficiency of 98.4 %, outperforming most reported MOF‐based electrocatalysts. This work provides new insights into the design of high‐performance NO3−RR electrocatalysts. [ABSTRACT FROM AUTHOR]

Drawing inspiration from the nitrate reductase enzymes, which catalyze nitrate to nitrite in nature, here a bio‐inspired, reduced molybdenum oxide (MoOx) shell is introduced that is grown on top of a dendritic nickel foam core (NiNF). The resulting MoOx/NiNF material is prepared via a facile, two‐step electrodeposition strategy using commercially available, low‐cost precursors. This catalytic material displays a remarkable faradaic efficiency (FE) of 99% at −0.5 V versus RHE and a high ammonia (NH3) yield rate of up to 4.29 mmol h−1 cm−2 at −1.0 V versus RHE in neutral media. Most importantly, MoOx/NiNF exhibits exceptional stability for the nitrate reduction reaction (NO3RR), maintaining operation for over 3100 h at a high current density of −650 mA cm−2, with a yield rate of 2.6 mmol h−1 cm−2 and a stable average NH3 FE of ≈83%. Through combined XPS and in situ Raman spectroscopy it is shown that the pronounced affinity of MoOx/NiNF for nitrate is associated with a substantial presence of oxygen vacancies within the material. [ABSTRACT FROM AUTHOR]

Ammonia is emerging as a liquefied and renewable‐energy carrier of global interest in the future. The electrochemical reduction of nitrate is widely acknowledged as an alternative to the traditional Haber–Bosch process for ammonia production. However, it is observed that certain catalysts can undergo spontaneous oxidation–reduction reactions with nitrate to some extent, leading to the calculated ammonia Faradaic efficiency exceeding 100%. However, there is a lack of accurate experimental validation as well as effective solutions. To address these problems, it is verified that the spontaneous reaction between the catalyst and nitrate impacts on the calculation of electrocatalytic nitrate reduction performance. Meanwhile, an updated and optimized experimental strategy is proposed to address the interference caused by the spontaneous reaction. This work will significantly contribute to more accurate and reliable electrocatalytic nitrate reduction research. [ABSTRACT FROM AUTHOR]

Increasing plastic pollution is a serious environmental problem as widespread production and inadequate disposal of plastic materials lead to adverse impacts on ecosystems. The structural and functional characteristics of the anaerobic microbial community contacting with extruded polystyrene (XPS) waste were investigated under methanogenic (MG) and nitrate-(NR) and sulfate-reducing (SR) conditions. The presence of XPS in the microbial community was shown to have no negative effect on the processes of biogas formation and, on the contrary, resulted in an increase in the yield of methane and volatile fatty acids and a change in their ratio. Microparticles of different sizes were found in the culture liquid of the variants with XPS: 2.4 × 106/mL (NR), 1.2 × 106/mL (SR), and 0.4 × 106/mL (MG), while no microparticles were found in the control variants. Scanning electron microscopy revealed that in all experimental variants the surface of the polymer became looser, more textured, with formation of irregularities, cracks, and holes. Increased diversity in the microbial community associated with an increase in the number of microbial morphotypes, correlated with the results of high-throughput sequencing of the 16S rRNA gene. When XPS was introduced into an anaerobic community incubated in different donor-acceptor conditions, the number of microbial groups in it increased, as well as the proportion of hydrolytic and acidogenic bacteria (Sedimentibacter, Lentimicrobium), acetogenic syntrophs (Syntrophomonas, Desulfovibrio, Geobacter), and methanogenic archaea (Methanosarcina, Methanobacterium). Our study showed that the XPS waste was not inert for the microbial community, the contact with it resulting in significant changes in its structure and functioning. Changes in the sample surface, emergence of microparticles, and differences in the composition of the intermediate and terminal metabolic products may indicate slow partial degradation of the plastic via fragmentation. However, since the experiments were carried out using household XPS containing various fillers apart from the main polymer, it is probable that, along with polystyrene, additional substances included in its composition (plasticizers, dyes, etc.) are also subject to degradation. The ability of microorganisms to degrade the polymer itself requires further research. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction to ammonia (NRA) is a promising approach for alleviating energy crisis and water pollution. Current NRA catalysts are challenged to simultaneously improve the rate of the adsorption and desorption processes to further increase the total activity due to the Brønsted−Evans−Polanyi (BEP) relationships. Herein, a two‐step Joule heating method is utilized for the preparation of Ni0.25Cu0.5Sn0.25 nanometallic glass containing synergistic catalytic sites to simultaneously enhance the adsorption and desorption processes. Kelvin probe force microscopy reveals a pronounced oscillatory behavior in the surface potential of Ni0.25Cu0.5Sn0.25 nanometallic glass, which is an important feature of the synergistic catalytic site, and an empirical formula is proposed to quantitatively characterize its oscillatory characteristic. In situ electrochemical Raman spectroscopy indicates the promotion of nickel and tin atoms for nitrate adsorption and ammonia desorption processes, respectively. DFT calculations demonstrated that Ni0.25Cu0.5Sn0.25 presents a wide range of adsorption energy distributions to favor the multisite synergistic catalysis. The present work provides new ideas for the design and understanding of highly active NRA catalysts. [ABSTRACT FROM AUTHOR]

Considering the substantial role of ammonia, developing highly efficient electrocatalysts for nitrate‐to‐ammonia conversion has attracted increasing interest. Herein, we proposed a feasible strategy of p–d orbital hybridization via doping p‐block metals in an Ag host, which drastically promotes the performance of nitrate adsorption and disassociation. Typically, a Sn‐doped Ag catalyst (SnAg) delivers a maximum Faradaic efficiency (FE) of 95.5±1.85 % for NH3 at −0.4 V vs. RHE and reaches the highest NH3 yield rate to 482.3±14.1 mg h−1 mgcat.−1. In a flow cell, the SnAg catalyst achieves a FE of 90.2 % at an ampere‐level current density of 1.1 A cm−2 with an NH3 yield of 78.6 mg h−1 cm−2, during which NH3 can be further extracted to prepare struvite as high‐quality fertilizer. A mechanistic study reveals that a strong p–d orbital hybridization effect in SnAg is beneficial for nitrite deoxygenation, a rate‐determining step for NH3 synthesis, which as a general principle, can be further extended to Bi‐ and In‐doped Ag catalysts. Moreover, when integrated into a Zn‐nitrate battery, such a SnAg cathode contributes to a superior energy density of 639 Wh L−1, high power density of 18.1 mW cm−2, and continuous NH3 production. [ABSTRACT FROM AUTHOR]

In this experiment, C3N5 was synthesized by pyrolysis of 3-amino-1,2,4 triazole material, and then 1% Co-C3N5, 3% Co-C3N5, 5% Co-C3N5, 7% Co-C3N5, and 9% Co-C3N5 were synthesized by varying the mass ratio of cobalt chloride to C3N5 by stirring and ultrasonic shaking. SEM, XPS, and XRD tests were performed on the synthesized materials. The experimental results showed that Co atoms were successfully doped into C3N5. The electrocatalytic reduction experiments were performed to evaluate their NH3 yields and electrochemical properties. The results showed that the ammonia yield obtained by the electrolysis of the 9% Co-C3N5 catalyst as the working electrode in a mixed electrolytic solution of 0.1 mol/L KNO3 and 0.1 mol/L KOH for 1 h at a potential of −1.0 V vs. RHE was 0.633 ± 0.02 mmol∙h−1∙mgcat−1, and the Faraday efficiency was 65.98 ± 2.14%; under the same experimental conditions, the ammonia production rate and Faraday efficiency of the C3N5 catalyst were 0.049 mmol∙h−1∙mgcat−1 and 16.41%, respectively, and the ammonia production rate of the C3N5 catalyst was nearly 13-fold worse than the 9% Co-C3N5, which suggests that Co can improve the Faraday efficiency and ammonia yield of the electrocatalytic reduction of NO3−. This is due to the strong synergistic effect between the cobalt and C3N5 components, with C3N5 providing abundant and homogeneous sites for nitrogen coordination and the Co-N species present in the material being highly efficient active sites. The slight change in current density after five trials of 9% Co-C3N5 and the decrease in ammonia yield by about 12% in five repetitions of the experiment indicate that 9% Co-C3N5 can be recycled and work stably in electrocatalytic reactions and has good application prospects. [ABSTRACT FROM AUTHOR]

The electrochemical co‐reduction of CO2 and NO3− to urea is an alternative to traditional urea synthesis. However, the significant difference in the energy barriers and reaction rates for CO2 and NO3− reduction restricts the efficiency of the CN coupling. Herein, we report a strategy to coordinate the CN coupling intermediates by unilaterally increasing the efficiency of CO2 reduction to match that of facile NO3− reduction. We demonstrate this strategy using an electrochemical reaction system consisting of a Cu2O‐loaded ordered gas‐diffusion electrode, which offers a high urea yield rate of 1373.5 μg h−1 mgcat.−1 at a low applied potential of −0.6 V versus RHE. This work not only provides a feasible strategy to coordinate the reductive coupling of CO2 and NO3−, but also brings new insight into the reaction mechanism of urea electrosynthesis. [ABSTRACT FROM AUTHOR]

For photoelectrocatalytic cells, a limitation exists in finding appropriate photoelectrode configurations that couple efficient extraction of high‐energy electrons from absorbed photons and selective catalysis. Here we report an organic p‐n junction approach to fabricate molecular photoelectrodes for conversion of solar energy and nitrate into valuable ammonia product. Solar irradiation of the photoelectrode generates charge‐separated states with electrons and holes spatially separated at the n‐type and p‐type components, as revealed by surface photovoltage mapping, at a quantum yield of 90 %. The high‐flux photogenerated electrons are rapidly transferred to the catalyst for solar ammonia production from nitrate reduction at an external quantum efficiency (EQE) and an internal quantum efficiency (IQE) of 57 % and 86 %, respectively. Time‐resolved spectroscopic studies reveal that the large IQE originates from the combined high efficiencies for photoelectron generation, catalyst activation and dark catalysis. In a flow‐cell setup coupled with a silicon solar cell, the photoelectrode without bias generates photocurrent of 57 mA cm−2 and ammonia at an EQE of 52 %. [ABSTRACT FROM AUTHOR]

The electrocatalytic nitrate reduction reaction (NO3−RR) presents a promising pathway for achieving both ammonia (NH3) electrosynthesis and water pollutant removal simultaneously. Among various electrocatalysts explored, 2D materials have emerged as promising candidates due to their ability to regulate electronic states and active sites through doping. However, the impact of doping effects in 2D materials on the mechanism of NO3−RR remains relatively unexplored. Here, Ni‐doped MoS2 (Ni‐MoS2) nanosheets are investigated as a model system, demonstrating enhanced NO3−RR performance compared to undoped counterparts. By controlling the doping concentration, the Ni‐MoS2 nanosheets achieve a remarkable faradic efficiency (FE) of 92.3% for NH3 at −0.3 VRHE with excellent stability. The mechanistic studies reveal that the elevation of the NO3−RR performances originates from the generation of more active hydrogen and the acceleration of the reaction from nitrite (NO2−) to NH3 facilitated by Ni doping. Combining the experimental observations and theoretical calculations it is revealed that the appropriate Ni doping level in MoS2 can enhance *NO3 adsorption strength, thereby facilitating subsequent electrocatalytic steps. Together with the demonstration of Zn−NO3− and Zn−NO2− battery devices, the work provides new insights into the design and regulation of the active sites in 2D material catalysts for efficient NO3−RR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Newly synthesized Cu 3 N catalyst was employed for electrocatalytic nitrate reduction and ammonia production. • The strategy of balancing *H 2 O and *NO 3 intermediates adsorption for enhanced NO 3 RR was highlighted. • In-situ and ex-situ analysis verify the potential driven reconstruction and rehabilitation of Cu 3 N. Nitrate in surface and underground water caused systematic risk to the ecological environment. The electrochemically reduction of nitrate into ammonia (NO 3 RR), offering a sustainable route for nitrate containing wastewater treatment and ammonia fertilizer conversion. Exploration of catalyst with improved catalytic activity with lower energy barriers is still challenging. Here, we report a copper nitride (Cu 3 N) catalyst with moderate *NO x and *H 2 O intermediates adsorptions showed enhanced NO 3 RR performance. Density functional theory calculations reveals that the unique electronic structure of Cu 3 N provides efficient active sites for NO 3 RR, thus enabled balanced adsorption of *NO 3 and *H 2 O (ΔE descriptor), sufficient active hydrogen, and moderate intermediate (*NO 3 → HNO 3 , *NH 2 →*NH 3) adsorption energy. Notably, the in-situ analysis technology revealed potential-driven reconstruction and rehabilitation of Cu 3 N, forming possible nitrogen vacancy, thus implied for better mechanism understanding. The NO 3 RR activity of Cu 3 N surpasses that of most recent catalysts and demonstrates superior stability and implies the application for NH 4 + fertilizer recovery, which maintaining an NH 3 Faradaic efficiency of 93.1 % and high yield rate of 2.9 mg cm2h−1 at −0.6 V versus RHE. These findings broaden the application scenarios of Cu 3 N catalyst for ammonia synthesis and provide strategy on improving NO 3 RR performance. [ABSTRACT FROM AUTHOR]

Amorphous materials are distinguished by their exceptional attributes, notably their expansive surface area and the profusion of active sites they present. Consequently, the amorphization process stands as an efficacious strategy to augment the catalytic efficacy of electrocatalysts. This is achieved through the meticulous construction of the surface architecture and the precise modulation of the electronic configuration of these materials. Therefore, this review aims to offer a thorough examination of the latest progress in the application of amorphous materials for the enhancement of electrocatalytic processes, with a particular emphasis on the nitrate (NO3−) reduction reaction (NITRR) and the carbon dioxide reduction reaction (CO2RR). Initially, we delve into the structural benefits inherent to amorphous materials, outlining the diverse synthesis techniques and characterization methodologies utilized in their development. Following this, we illustrate the utilization of various amorphous materials in NITRR and CO2RR, accentuating how the amorphous framework influences electrocatalytic activities. Concludingly, we encapsulate the merits and the obstacles encountered in the application of amorphous electrocatalysts for NITRR and CO2RR, whilst also forecasting the future direction for the creation of innovative amorphous electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO3RR) is a process that requires the participation of eight electrons and nine protons. The regulation of active hydrogen (H*) supply and a deep understanding of related processes are necessary for improving the ammonia yield rate and Faradaic efficiency (FE). Herein, we synthesized a series of atomically precise copper‐halide clusters Cu2X2(BINAP)2 (X=Cl, Br, I), among which the Cu2Cl2(BINAP)2 cluster shows the optimal ammonia FE of 94.0 % and an ammonia yield rate of 373 μmol h−1 cm−2. In situ experiments and theoretical calculations reveal that halogen atoms, especially Cl in Cu2Cl2(BIANP)2, can significantly affect the distance of alkali metal‐ionized water on the catalyst surface, which can promote the water dissociation to enhance the localized H* enrichment for the continues hydrogenation of nitrate to ammonia. This work explains the role of H* in the hydrogenation process of NO3RR and the importance of localized H* enrichment strategy for improving the FEs. [ABSTRACT FROM AUTHOR]

Ammonia plays a vital role in present agriculture and industry, and is also regarded as a next-generation clean energy carrier. The development of electrocatalysis raises an opportunity to make ammonia synthesis compatible with intermittent and variable renewable energy sources such as solar and wind energy. However, the direct ammonia electrosynthesis from N2 reduction is still challenging due to the much easier hydrogen evolution competition reaction. In this perspective, we propose a novel strategy for ammonia electrosynthesis from air and water based on the coupling of anodic nitrogen oxidation and cathodic nitrate reduction. Possible methods for breaking the bottlenecks of anodic nitrogen oxidation and cathodic nitrate reduction are discussed separately. After that, key issues that need to be considered in the coupled system are proposed for the application of this strategy. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrocatalytic nitrate reduction reaction presents a promising avenue for environmentally friendly ammonia (NH 3) synthesis and wastewater treatment. An essential aspect to consider is the meticulous design of electrocatalysts. This study explores the utilization of a Ni-Co alloy nanosheet-decorated three-dimensional titanium dioxide (3D-TiO 2) nanobelts electrodeposited on titanium meshes (Ni x Co y @TiO 2 /TM) for efficient electrocatalytic NH 3 production. The optimized Ni 1 Co 3 @TiO 2 /TM electrode achieves a significant NH 3 yield of 676.3 ± 27.1 umol h−1 cm−2 with an impressive Faradaic efficiency (FE) of 95.1 % ± 2.1 % in a 0.1 M KOH solution containing 0.1 M NO 3 − at −0.4 V versus the reversible hydrogen electrode. Additionally, the electrode demonstrates exceptional electrochemical activity for NH 3 synthesis in simulated wastewater, delivering an outstanding NH 3 yield of 751.6 ± 44.3 umol h−1 cm−2 with a FE of 96.8 % ± 0.4 % at the same potential of −0.4 V. Moreover, the electrode exhibits minimal variation in current density, NH 3 yields and FEs throughout the 24-h stability test and the 20-cycle test, demonstrating its excellent stability and durability. This study offers a straightforward electrodeposited approach for the development of 3D-nanostructured alloys as catalysts for NH 3 electrosynthesis from nitrates at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical nitrate reduction to ammonia is a promising alternative strategy for producing valuable ammonia. This prospective route, however, is subject to a slow electrocatalytic rate, which resulted from the weak adsorption and activation of intermediate species, and the low density electron cloud of active centers. To address this issue, we developed a novel approach by doping boron into metal hydroxyl oxides to adjust the electronic structure of active centers, and consequently, led a significant improvement in the Faraday efficiency upto approaching 100 %, as well as an impressive ammonia yield upto approximately 23 mg/h mgcat−1 at −0.6 V vs. reversible hydrogen electrode (RHE). Experimental data in mechanism demonstrate that the doped boron play a crucial role in modulating the local electronic environment surrounding the active sites Co. In situ Raman and FTIR spectra provide evidences that boron facilitates the formation of deoxidation and hydrogenation intermediates. Additionally, density functional theory (DFT) calculations support the notion that boron doping enhances the adsorption capability of intermediates, reduces the reaction barrier, and facilitates the desorption of NH 3. [ABSTRACT FROM AUTHOR]

[Display omitted] Atomically dispersed iron–nitrogen-carbon (Fe–N 4 –C) catalysts show great promises for the electrocatalytic nitrate (NO 3 −) reduction to ammonia (NH 3). Nevertheless, the microenvironmental engineering of the single Fe active sites for further optimizing the catalytic performance remains a challenge. Herein, we proposed to regulate the coordination environment of single Fe active sites to boost its intrinsic electrocatalytic activity for NO 3 − –to–NH 3 conversion by the incorporation of new heteroatoms, including B, C, O, Si, P, and S. Our results revealed that most of the candidates possess low formation energies, showing great potential for experimental synthesis. Moreover, incorporating heteroatoms effectively modulates the charge redistribution and the d–band center of single Fe active sites, enabling the regulation of the binding strength of nitrogenous intermediates. As a result, the N and C coordinated Fe active site (Fe–N 3 C) exhibits superior catalytic performance for NO 3 − electroreduction with a relatively low limiting potential (–0.13 V) due to its optimal adsorption strength with nitrogenous intermediates induced by its moderate charge and d–band center. Importantly, our experimental measures confirmed such theoretical prediction: a maximum NH 3 yield rate of 21.07 mg h−1 mg cat. −1 and 95.74 % Faradaic efficiency were achieved for NO 3 − electroreduction on Fe–N 3 C catalyst. These findings not only suggest a highly efficient catalyst for nitrate reduction but also provide insight into how to design and prepare electrocatalysts with enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

The CoP 3 and Cu 3 P sites with synergistic effects were arranged at the interface of the integrated self-supporting electrode, which realizes the conversion of nitrate to high value-added ammonia by nearly 100% under working conditions, and realizes multi-actual scenario application in the integrated device to promote the distributed production of ammonia and the storage and conversion of green energy. [Display omitted] • Functionally differentiated CoP 3 and Cu 3 P sites were constructed on self-supporting copper foam. • The ammonia yield rate is at the leading level and the Faradaic efficiency is close to 100% • Capture of solar energy to drive continuous ammonia synthesis. • Realize self-driven synthesis of ammonia and output electricity at the same time. • Efficient ammonia synthesis is realized in complex water environment. The promising electrocatalytic nitrate reduction reaction (eNitRR) for distributed ammonia synthesis requires the fine design of functionally compartmentalised and synergistically complementary integrated catalysts to meet the needs of low-cost and efficient ammonia synthesis. Herein, the partitionable CoP 3 and Cu 3 P modules were built on the copper foam substrate, and the functional differentiation promoted the catalytic performance of the surface accordion-like CoP 3 /Cu 3 P@CF for eNitRR in complex water environment. Where the ammonia yield rate is as high as 23988.2 μg h−1 cm−2, and the Faradaic efficiency is close to 100 %. With CoP 3 /Cu 3 P@CF as the core, the assembled high-performance Zn-nitrate flow battery can realize the dual function of ammonia production and power supply, and can also realize the continuous production of ammonia with high selectivity driven by solar energy. The ammonia recovery reaches 753.9 mg L-1, which shows the superiority of CoP 3 /Cu 3 P@CF in multiple application scenarios and provides important experience for the vigorous development of eNitRR. Density functional theory calculation reveal that CoP 3 and Cu 3 P sites play a relay synergistic role in eNitRR catalyzed by CoP 3 /Cu 3 P@CF. CoP 3 first promotes the activation of NO 3 – to *NO 3 H, and then continuously provides proton hydrogen for the eNitRR on the surface of Cu 3 P, which relays the synergistic catalytic effect to promote the efficient conversion of NO 3 – to NH 3. This study not only develops a catalyst that can promote the efficient reduction of NO 3 – to ammonia through an easy-to-obtain innovative strategy, but also provides an alternative strategy for the development of eNitRR that is suitable for multiple scenarios and meets the production conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-CoO/CuO with notable electrocatalytic capabilities is easily prepared. • More than 98% of nitrate was removed by Fe-CoO/CuO@CF electrode. • Nitrate was nearly entirely (99.7%) converted into nitrogen gas. • Fe-CoO/CuO@CF electrode exhibits remarkable reusability. The electrocatalytic reduction of nitrate ions (NO 3 −) to nitrogen gas (N 2) has emerged as an effective approach for mitigating nitrate pollution in water bodies. However, the development of efficient and highly selective cathode materials remains challenging. Conventional copper-based catalysts often exhibit low selectivity because they strongly adsorb oxygen. In this study, a straightforward solvothermal and pyrolysis method was used to grow iron-doped cobalt–copper oxide heterogeneous structures on copper foam surfaces (Fe–CoO/CuO@CF). Then, the effects of the applied potential, initial NO 3 − concentration, Cl− concentration, electrolyte pH, and different catalysts on the catalyst performance were investigated. Compared with recently reported congeners, Fe–CoO/CuO@CF is less expensive and exhibits outstanding activity for NO 3 − reduction. Meanwhile, under a cathode potential of − 1.31 V vs. Ag/AgCl, Fe–CoO/CuO@CF degrades 98.6 % of NO 3 − in 200 min. In addition, when employing a method inspired by NH 4 + removal by breakpoint chlorination, N 2 selectivity over Fe–CoO/CuO@CF was raised from 10 % without Cl− to 99.7 % when supplemented with Cl−. The catalyst demonstrated excellent cyclic stability, maintaining a high electrocatalytic activity for the conversion of NO 3 − to N 2 gas over eleven cycles. Moreover, Fe–CoO/CuO@CF enabled 63.7 % removal of NO 3 − from wastewater (50 mg/L NO 3 −–N) prepared from natural water, with 100 % conversion to N 2. Computational studies showed that iron doping decreased the free energy change of the intermediate of NO 3 − reduction reaction. This study provides an effective strategy for the electrochemical reduction of nitrate to nitrogen gas and offers good prospects for addressing nitrate pollution. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction reaction (NO3−RR) presents an environmentally friendly approach for efficient NO3− pollutant removal and ammonia (NH3) production, compared to the conventional Haber–Bosch approach. While core/shell engineering has demonstrated its potential in enhancing NO3−RR performance, significant synthetic challenges and limited shell layer modification capabilities impede the exploration of high‐performance NO3−RR core/shell catalysts. Herein, CuCoO/Co(OH)2 core/shell structure via in situ electrochemical activation is synthesized. The catalyst delivers a maximum NH3 Faradaic efficiency (FE) of 94.7% at −0.5 VRHE with excellent durability and selectivity for NH3 over a wide range of potentials in NO3−RR, surpassing the electrocatalytic performance of both undoped shell and core components. The outstanding performance Cu─CoO/Co(OH)2 is ascribed to the enhanced charge transfer, stabilization of key reaction intermediates, and regulation of hydrogen adsorption over Cu‐doped core/shell structure. Furthermore, the assembled Zn−NO3− battery device attains a peak current density exceeding 32 mA cm−2 and an NH3 yield of up to 145.4 µmol h−1 cm−2. The work offers a novel core/shell engineering strategy in electrocatalytic NO3−RR and sheds light on the doping effects on the electrochemical NH3 synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] Electricity-driven nitrate (NO 3 −) to ammonia (NH 3) conversion presents a unique opportunity to simultaneously eliminate nitrate from sewage while capturing ammonia. However, the Faradaic efficiency and ammonia yield in this eight-electron process remain unsatisfactory, underscoring the critical need for more effective electrocatalysts. In this study, a RuCo alloy nanosheets electrodeposited on pinewood-derived three-dimensional porous carbon (RuCo@TDC) is introduced as a highly-efficient electrocatalyst for the nitrate reduction reaction. The RuCo@TDC catalyst exhibits superior electrocatalytic performance, achieving the highest NH 3 yield of 2.02 ± 0.11 mmol h−1 cm−2 at −0.6 V versus the reversible hydrogen electrode (vs. RHE) and the highest Faradaic efficiency of 95.7 ± 0.8 % at −0.2 V vs. RHE in an electrolyte mixture of 0.1 M KOH and 0.1 M KNO 3. Furthermore, the Zn-NO 3 − battery using RuCo@TDC as the cathode provides a maximum power density of 2.46 mW cm−2 and a satisfactory NH 3 yield of 1110 μg h−1 cm−2. [ABSTRACT FROM AUTHOR]

The electrochemical NOx reduction reactions, involving nitrate and nitrite reduction reactions (NO3−RR and NO2−RR), have emerged as promising approaches for both NO3− and NO2− removal, and ammonium (NH3) synthesis under ambient conditions. However, the incorporation and stabilization of sulfur dopants in the catalysts for efficient NOx reduction are rarely explored, leading to an unclear effect of sulfur on the NOx reduction mechanism. Herein, sulfur‐doped Cu2O (S‐Cu2O) nanoneedle arrays via in situ electrochemical treatment are synthesized. The S‐Cu2O catalyst possesses excellent durability and selectivity for NH3 over a wide range of potentials in NO3−RR, attaining a maximum NH3 Faradaic efficiency of 94% at −0.6 VRHE and a maximum NH3 yield as high as 1.06 mmol h−1 cm−2. In NO3−RR, the sulfur dopant can accelerate the step from NO2− to NH3, contributing superior performance in NO2−RR and assembled Zn−NO2− battery device. Density functional theory (DFT) calculations reveal that the presence of sulfur can enhance the initial step of *NO3 adsorption, lower the reaction barriers for the formation of *NHO intermediate, and activate the H2O dissociation process. The work sheds light on the role of sulfur in enhancing electrocatalytic performance and provides a unique perspective for understanding the NOx reduction mechanism. [ABSTRACT FROM AUTHOR]

Ammonia, as a high‐energy‐density carrier for hydrogen storage, is in great demand worldwide. Electrocatalytic nitrate reduction reaction (NO3RR) provides a green NH3 production process. However, the complex reaction pathways for NO3RR to NH3 and the difficulty in controlling intermediate products limit the reduction process. Herein, by incorporating atomic‐level bismuth (Bi) into CuCo2O4 hollow carbon nanofibers, the catalytic activity of the electrocatalyst for NO3RR is enhanced. The maximum Faradaic efficiency of Bi1‐CuCo2O4 is 95.53%, with an NH3 yield of 448.74 µmol h−1 cm−2 at −0.8 V versus RHE. Density Functional Theory calculations show that the presence of Bi lowers the reaction barrier for the hydrogenation step from *NO2 to *NO2H, while promoting mass transfer on the release of *NH3 and the reactivation of surface‐active sites. Differential charge density calculations also show that after Bi doping, the charge supplied by the catalyst to NO3− increases from 0.62 to 0.72 e‐, thus reasoned for enhanced NO3RR activity. The established nitrate‐Zn battery shows an energy density of 2.81 mW cm−2, thus implying the potential application. [ABSTRACT FROM AUTHOR]

Electrochemical nitrate reduction reaction (NO3RR) is a promising approach to achieve remediation of nitrate‐polluted wastewater and sustainable production of ammonia. However, it is still restricted by the low activity, selectivity and Faraday efficiency for ammonia synthesis. Herein, we propose an effective strategy to modulate the electrolyte microenvironment in electrical double layer (EDL) by mediating alkali metal cations in the electrolyte to enhance the NO3RR performance. Taking bulk Cu as a model catalyst, the experimental study reveals that the NO3−‐to‐NH3 performance in different electrolytes follows the trend Li+

The conversion of nitrate to ammonium, i.e., nitrate reduction, is a major consumer of reductants in plants. Previous studies have reported that the mitochondrial alternative oxidase (AOX) is upregulated under limited nitrate reduction conditions, including no/low nitrate or when ammonium is the sole nitrogen (N) source. Electron transfer from ubiquinone to AOX bypasses the proton-pumping complexes III and IV, thereby consuming reductants efficiently. Thus, upregulated AOX under limited nitrate reduction may dissipate excessive reductants and thereby attenuate oxidative stress. Nevertheless, so far there is no firm evidence for this hypothesis due to the lack of experimental systems to analyze the direct relationship between nitrate reduction and AOX. We therefore developed a novel culturing system for A. thaliana that manipulates shoot activities of nitrate reduction and AOX separately without causing N starvation, ammonium toxicity, or lack of nitrate signal. Using shoots processed with this system, we examined genome-wide gene expression and growth to better understand the relationship between AOX and nitrate reduction. The results showed that, only when nitrate reduction was limited, AOX deficiency significantly upregulated genes involved in mitochondrial oxidative stress, reductant shuttles, and non-phosphorylating bypasses of the respiratory chain, and inhibited growth. Thus, we conclude that AOX alleviates mitochondrial oxidative stress and sustains plant growth under limited nitrate reduction. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction to ammonia (eNRA) presents a promising approach for nitrate degradation and ammonia synthesis. The crucial factor in achieving efficient eNRA lies in the development of catalysts with high activity, selectivity, and stability. Herein, we utilized high–throughput first−principle computation to investigate the potential application of transition metal single atoms anchored on defective WS 2 monolayer (WS 2 @TM) as electrocatalysts for eNRA. Sulfur defects naturally provide hosting sites for anchoring TM atoms on WS 2 monolayer. Out of the 27 WS 2 @TM (3d to 5d period common TM's) catalysts considered, 16 are both thermodynamically stable and experimentally feasible. Among these 16 candidates, WS 2 @Fe and WS 2 @Co catalysts show promising potential, with limiting potentials of −0.40 and −0.27 V, respectively. Furthermore, the WS 2 @Fe and WS 2 @Co catalysts demonstrate high selectivity towards ammonia over hydrogen evolution reaction (HER) and by−products, indicating their potential as effective electrocatalysts for eNRA. This research comprehensively explores the discovery of novel eNRA catalysts and provides fundamental insights. It will also contribute to the development of efficient electrocatalysts for ammonia synthesis and encourage further experimental investigation in this field. [Display omitted] • The electrocatlytic nitrate reduction to ammonia (eNRA) performance of defective single layer WS 2 catalysts decorated with transition metal atoms are systematically studied. • Sulfur defects innately generated during the preparation of WS 2 monolayers are natural hosting sites for TM atoms. • The competition between eNRA and HER is evaluated, and product selectivity of NH 3 to N 2 O/N 2 byproducts are considered. • Of the 27 TM@WS 2 catalysts considered, the WS 2 @Fe and WS 2 @Co catalysts are found to be promising for the production of NH 3 with very low limiting potentials. [ABSTRACT FROM AUTHOR]

Denitrification and nitrate-ammonification are the responsible processes for nitrate removal in the estuaries. Temperature, nitrate and organic carbon availability are key factors controlling a rate of the nitrate reduction processes. This mixed cultures chemostat study investigates the competition ability and their nitrate reduction end-products of the bacteria isolated from an estuary at different temperatures. This study will help us to understand the seasonal nitrate reduction processes in an estuary. The experiments showed that a nitrate-ammonifier was the predominant process in the steady-state chemostat at high temperature. While a facultative denitrifier-nitrate ammonifier was the predominant process at low temperature. However, the main end products of nitrate reduction at high temperature were up to 61% N2 indicating a denitrifier still had an important role in the end products of nitrate reduction in the estuary. The data also showed that a nitrite respiring bacterium reduced nitrite to N2, that responsible for approximately 6-9% of total N2 produced in the culture. This study confirmed that nitrate ammonifiers out-compete denitrifiers at high temperature, however, denitrifiers still had an important role in end products of nitrate reduction. [ABSTRACT FROM AUTHOR]

The microbe-mediated conversion of nitrate (NO3−) to ammonium (NH4+) in the nitrogen cycle has strong implications for soil health and crop productivity. The role of prokaryotes, eukaryotes and their phylogeny, physiology, and genetic regulations are essential for understanding the ecological significance of this empirical process. Several prokaryotes (bacteria and archaea), and a few eukaryotes (fungi and algae) are reported as NO3− reducers under certain conditions. This process involves enzymatic reactions which has been catalysed by nitrate reductases, nitrite reductases, and NH4+-assimilating enzymes. Earlier reports emphasised that single-cell prokaryotic or eukaryotic organisms are responsible for this process, which portrayed a prominent gap. Therefore, this study revisits the similarities and uniqueness of mechanism behind NO3− -reduction to NH4+ in both prokaryotes and eukaryotes. Moreover, phylogenetic, physiological, and genetic regulation also shed light on the evolutionary connections between two systems which could help us to better explain the NO3−-reduction mechanisms over time. Reports also revealed that certain transcription factors like NtrC/NtrB and Nit2 have shown a major role in coordinating the expression of NO3− assimilation genes in response to NO3− availability. Overall, this review provides a comprehensive information about the complex fermentative and respiratory dissimilatory nitrate reduction to ammonium (DNRA) processes. Uncovering the complexity of this process across various organisms may further give insight into sustainable nitrogen management practices and might contribute to addressing global environmental challenges.Highlights: DNRA is one of the potent beneficial pathways to maintain nitrogen pool in the system. Nitrate reduction is governed by both prokaryotes and eukaryotes. Evolutionary linkage between these organisms is also established for NO3- reduction to ammonium. F-DNRA needs energy through substrate-level phosphorylation, whereas R-DNRA through oxidative phosphorylation. Post-translational and epigenetic modifications are the major factors influencing NO3- reduction. [ABSTRACT FROM AUTHOR]

Electrochemically converting nitrate into ammonia (ECNA) is expected to achieve wastewater treatment combined with distributed ammonia generation, which is beneficial to restoring the globally disrupted nitrogen cycle. While sluggish reaction kinetics and insufficient selectivity towards ammonia generation greatly hinder the practical application of ECNA. In this study, chloride-derived bimetallic Cu–Fe catalysts with flexible Cu/Fe ratios confined by nitrogen-doped carbon (CuxFey/CN) were constructed through reactive mechanical milling combined with thermal pyrolysis, enabling stable and efficient nitrate-to-ammonia conversion. The CN coating effectively prevents further oxidation of Fe2+, promoting electron transfer from Fe2+ to Cu+ and maintaining the highly reactive center Cu+/Cu stable. The optimized Cu3Fe/CN700-15 sample exhibits good nitrate conversion efficiency of 57.0% and ammonium selectivity of 61.6% within 6 h at −0.7 V relative to the reversible hydrogen electrode (vs. RHE). This work provides a new idea for stable and sustainable bimetallic denitrification. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of nitrate (NO3RR) to ammonia offers a promising approach for mitigating the environmental impact of NO3–, while simultaneously enabling the synthesis of NH3 under ambient conditions. Recently, single-atom catalysts (SACs) have been proven to have attractive activity on NO3RR, and better catalysts with enhanced activity and stability are still in demand. Here, we report the efficient boosting of NH3 production via the NO3RR using boron-doped Fe SAC (Fe-BCN). Fe-BCN is a normal 12-hedral nanoparticle with a size of 500 nm. The NH3 Faradaic efficiency of Fe-BCN reached 97.48%, with a high ammonia production rate of 2.17 mg cm–2 h–1, in an alkaline electrolyte environment at an electrode potential of −0.3 V vs reversible hydrogen electrode. Density functional theory calculations revealed the strategy of introduced B regulating the intermediate adsorption on Fe-BCN, which enhanced the NO3RR activity. Furthermore, leveraging the high NO3RR activity of Fe-BCN, a nitrate-zinc battery with a power density of 0.90 mW cm–2 was constructed by using Fe-BCN as the cathode and zinc as the anode, respectively. This research demonstrates the broad prospects of Fe-BCN in the NO3RR and provides insights for high-performance Fe SAC electrode materials. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO 3 RR) provides a promising method for ammonia (NH 3) producing. It is urgent to develop efficient catalysts with improved NO 3 RR performance. In this paper, Cu 3 P@Co(OH) 2 /CF heterostructure catalyst is constructed by electrodeposition of cobalt hydroxide (Co(OH) 2) nanosheet on the surface of copper phosphide (Cu 3 P) nanorod, and used as a self-supporting cathode for electrocatalytic reduction of nitrate to ammonia. The NH 3 yield reaches 0.19 mmol h−1 cm−2 at a potential of −0.17 V vs. RHE, and the faraday efficiency (FE) is 86.7 %. The study manifests that the built-in electric field generated at the p-n heterojunction interface optimizes the electron migration kinetics, and promotes the adsorption of nitrate and the convention of intermediate product NO 2 − into ammonia. As a consequence, the selectivity of NH3 is improved. The Zn-nitrate battery is assembled with the designed catalyst as the cathode, to reach a peak power density of 5.16 mW cm−2. The prepared catalyst realizes three effective functions: power output, ammonia synthesis, and nitrate pollutants treatment. [Display omitted] • Cu 3 P@Co(OH) 2 /CF heterostructure material was synthesized by low temperature phosphating and electrodeposition methods. • The built-in electric field at the p-n heterojunction promotes the convention of intermediate NO 2 − into ammonia. • Cu 3 P@Co(OH) 2 /CF effectively promotes the *H pathway for NO 3 − reduction to NH 3. • Zn-nitrate battery was built with Cu 3 P@Co(OH) 2 /CF cathode to realize multi-functional applications. [ABSTRACT FROM AUTHOR]

This article demonstrates boron carbon nitrogen compound supported platinum group (Pd/BCN, Pt/BCN and Ru/BCN) for electrocatalytic reduction of nitrate to ammonia. [Display omitted] • Highly efficient electrocatalytic NO 3 – reduction was realized by doped Pd,Ru,Pt/BCN. • Pd/BCN provided higher NH 4 + production rate and Faraday efficiency. • DFT revealed the molecular mechanism of Pd/BCN in the nitrate reduction process. The effective treatment of nitrate (NO 3 −) in water as a nitrogen source and electrocatalytic NO 3 − reduction to ammonia (NH 3) (NRA) have become preferred methods for NO 3 −-to-NH 3 conversion. Achieving efficient NO 3 −-to-NH 3 conversion requires the design and development of electrode materials with high activity and efficiency for the electrocatalytic NRA reaction. Herein, based on the special properties of dodecahydro- closo -dodecaborate anions, a BCN matrix, loaded with platinum-group nanoparticles (namely, Pd/BCN, Pt/BCN, and Ru/BCN), was prepared using a simple method for the electrocatalytic NRA reaction. Results showed that Pd/BCN exerts the best catalytic effect on the NRA reaction. The NH 3 production rate reached 12.71 mg h−1 mg cat. −1 at −1.0 V vs. RHE. Faraday efficiency reached 91.79 %, which can be attributed to the more uniform distribution of the nanoparticles. Furthermore, Pd/BCN exhibited high cycling stability and resistance to ionic interference. Moreover, the density functional theory calculations indicated that small and well-distributed Pd nanoclusters in the BCN matrix have a large active surface area and promote the catalytic process. This study provides a new strategy to design catalysts for green ammonia synthesis. [ABSTRACT FROM AUTHOR]

Development of highly active and selective electrocatalysts for the reduction of nitrate (NO3–) to ammonia is critical for the production of green ammonia. Herein, we designed and synthesized NiMoO4 nanocubes as an efficient electrocatalyst for nitrate reduction using deep eutectic solvents (DESs) as synthesis media. By constructing Mo and Ni dual-active sites, Mo facilitates NO3– adsorption/association, and Ni acts as an active hydrogen (*H) donating center. The amount and destination of *H can be regulated, which can effectively enhance the activity of the NO3– reduction to NH3 reaction (NO3–RR). The optimized sample possessed excellent NO3–RR activity. An NH3–N selectivity of up to 96.94% and a Faraday efficiency of up to 96.13% can be achieved at −0.4 V in a neutral solution. The catalytic NO3–RR mechanism was also investigated by density functional theory (DFT) calculations. This dual-active site electrocatalyst provides an alternative idea for the synthesis and application of high-performance NO3–RR catalysts. [ABSTRACT FROM AUTHOR]

The abiotic transformations of quinolones and tetracyclines facilitated by redox-active minerals has been studied extensively, however limited information is available regarding the antimicrobial activity and toxicity of their resultant transformation products. In this study, we first investigated the mechanisms underlying the transformation of two commonly used antibiotics, ciprofloxacin (CIP) and tetracycline (TC), by the ubiquitous redox soil mineral, birnessite (MnO2). Subsequently, we evaluated the impact of these transformation products on both the growth and activity of the environmental denitrifier Pseudomonas veronii. Following the reaction with birnessite, four transformation products for CIP and five for TC were identified. Remarkably, the antibacterial activity of both CIP and TC was lost upon the formation of transformation products during their interaction with birnessite. This loss of antimicrobial efficacy was associated with specific chemical transformations, such as the opening of the piperazine ring for CIP and hydroxylation and demethylation for TC. Interestingly, denitrifying activity, quantified in terms of nitrate reduction rates, remained unaffected by both CIP and TC at low concentrations that did not impact bacterial growth. However, under certain conditions, specifically at low concentrations of CIP, the second step of denitrification—nitrite reduction—was hindered, leading to the accumulation of nitrite. Our findings highlight that the transformation products induced by the mineral-mediated reactions of CIP or TC lose the initial antibacterial activity observed in the parent compounds. This research contributes valuable insights into the intricate interplay between antibiotics, redox-active minerals, and microbial activity in environmental systems. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of NO3− to NH3 holds promise for economic and environmental benefits, presenting an energy-efficient alternative to the traditional Haber–Bosch method. However, challenges exist due to its sluggish kinetics, multiple intermediates, and various reaction pathways. In this study, Mn-doped-Cu catalyst was synthesized and employed for electrochemical NO3−-to-NH3 conversion. The doping of Mn into Cu resulted in exceptional performance, achieving a FE of 95.8% and an NH3 yield rate of 0.91 mol g−1 h−1 at −0.6 V in a neutral electrolyte at low NO3− concentration. Detailed experimental studies and theoretical calculations revealed that the Mn dopant enhanced the kinetic rate of NO2−-to-NH3 and induced a distinct configuration of *NO. This alteration decreased the energy barrier of *NO-to-*NOH, consequently promoting the conversion of NO3−-to-NH3. [ABSTRACT FROM AUTHOR]

Ammonia (NH3), an indispensable component of the fertiliser industry, plays an important role in human life. Owing to negative environmental impacts and the high energy input of the industrial Haber-Bosch process, uncovering alternative sustainable technologies for NH3 production is crucial. Anthropogenic activities leading to an imbalance in the nitrogen cycle have resulted in excessive nitrate (NO3−) pollution. Electrochemical conversion of NO3− pollutant into value-added NH3 is a recent trend in wastewater management. Additionally, this method provides an added leverage of circumventing the need for highly inert nitrogen gas as a precursor in electrochemical NH3 synthesis. Therefore, the electrochemical nitrate reduction reaction (eNO3− RR) with a higher production rate and faradaic efficiency could be an appealing route for wastewater treatment and sustainable NH3 production. In this review article, an effort is made to provide an overview of the mechanisms involved, recent developments made on various electrocatalysts and also on NH3 quantification methods in eNO3− RR. Finally, this review article emphasises existing challenges and future outlooks in this field of research. This review article promotes ongoing research endeavours in the efficient conversion of NO3− into NH3. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of nitrate to ammonia (ENRA) provides an efficient approach to remove nitrate pollution and achieve ammonia production simultaneously. Herein, inspired by bio-enzyme in denitrifying bacteria, a carbon-coated nickel phosphide (NiPC) nanosheet derived from metal-organic frameworks (MOFs) is proposed as an efficient catalyst for ENRA. Through electron engineering, controllable Niδ+ in nickel phosphide is achieved by regulating the degree of phosphating, which enhances its activity for the hydrogenation of nitrate. As the result, Niδ+ becomes one of dominating factors determining the efficiency of the ENRA reaction in nickel phosphide. The optimal NiPC catalyst exhibits impressive property toward ENRA: NH4+ Faraday efficiency of 96.68%, NH4+ selectivity of 99.04%, and nitrate conversion rate of 90.43% under low nitrate concentration (200 mgL−1). This work opens a new avenue for the design of next-generation catalysts through electron engineering for ENRA. [ABSTRACT FROM AUTHOR]

Developing electrocatalysts that exhibit both high activity and ammonia selectivity for nitrate reduction is a significant and demanding challenge, primarily due to the complex nature of the multiple-electron reduction process involved. An encouraging approach involves coupling highly active precious metals with transition metals to enhance catalytic performance through synergy. Here, we report a ruthenium-nickel alloy catalyst with nanosheets (Ru-Ni NSs) structure that achieves a remarkable ammonia Faradaic efficiency of approximately 95.93%, alongside a yield rate of up to 6.11 g·h−1·cm−2. Moreover, the prepared Ru-Ni NSs exhibit exceptional stability during continuous nitrate reduction in a flow reactor for 100 h, maintaining a Faradaic efficiency of approximately 90% and an ammonia yield of 37.4 mg·L−1·h−1 using 0.05 M nitrate alkaline electrolyte. Mechanistic studies reveal that the catalytic process follows a two-step pathway, in which HONO serves as a migration intermediate. The presence of a partially oxidized Ru (002) surface enhances the adsorption of nitrate and facilitates the release of the migration intermediate by adjusting the strength of the electrostatic and covalent interactions between the adsorbate and the surface, respectively. On the other hand, the Ni (111) surface promotes the utilization of the migration intermediate and requires less energy for NH3 desorption. This tandem process contributes to a high catalytic activity of Ru-Ni NSs towards nitrate reduction. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate (NO3 - ) reduction reaction (NO3 RR) to ammonia (NH3 ) represents a sustainable approach for denitrification to balance global nitrogen cycles and an alternative to traditional thermal Haber-Bosch processes. Here, we present a supramolecular strategy for promoting NH3 production in water from NO3 RR by integrating two-dimensional (2D) molecular cobalt porphyrin (CoTPP) units into a three-dimensional (3D) porous organic cage architecture. The porphyrin box CoPB-C8 enhances electrochemical active site exposure, facilitates substrate-catalyst interactions, and improves catalyst stability, leading to turnover numbers and frequencies for NH3 production exceeding 200,000 and 56 s-1 , respectively. These values represent a 15-fold increase in NO3 RR activity and 200-mV improvement in overpotential for the 3D CoPB-C8 box structure compared to its 2D CoTPP counterpart. Synthetic tuning of peripheral alkyl substituents highlights the importance of supramolecular porosity and cavity size on electrochemical NO3 RR activity. These findings establish the incorporation of 2D molecular units into 3D confined space microenvironments as an effective supramolecular design strategy for enhancing electrocatalysis.

Addressing nitrate contamination in water bodies is a critical environmental challenge, and Intimately Coupling Photocatalysis and Biodegradation (ICPB) presents a promising solution. However, there is still debate about the effectiveness of ICPB in reducing nitrate under hypotrophic conditions. Further research is needed to understand its microbial metabolic mechanism and the functional changes in bacterial structure. Here we explored microbial metabolic mechanisms and changes in bacterial structure in ICPB reactors integrating a meticulously screened TiO2/g-C3N4 photocatalyst with biofilm. We achieved a 26.3% increase in nitrate reduction using 12.2% less organic carbon compared to traditional biodegradation methods. Metagenomic analysis of the microbial communities in ICPB reactors revealed evolving metabolic pathways conducive to nitrate reduction. This research not only elucidates the photocatalytic mechanism behind nitrate reduction in hypotrophic conditions but also provides genomic insights that pave the way for alternative approaches in water remediation technologies.

Abstract Background Macrophytes may modify benthic biodiversity and biogeochemistry via radial oxygen loss from roots. This condition contrasts sediments anoxia, allows roots respiration, and facilitates aerobic microbial communities and processes in the rhizosphere. Simultaneously, the rhizosphere can stimulate anaerobic microorganisms and processes via exudates or by favoring the build-up of electron acceptors as nitrate. As eutrophication often results in organic enrichment in sediments and large internal nutrients recycling, an interesting research question is to investigate whether plants maintain the capacity to stimulate aerobic or anaerobic microbial communities and processes also under elevated organic pollution. Methods A manipulative experiment was carried out under laboratory-controlled conditions. Microcosms containing bare sediments and sediments transplanted with the macrophyte Vallisneria spiralis L. were created. The effect of the plant was investigated on sediments with moderate (8%) and elevated (21%) organic matter content, after an acclimatization period of 30 days. Chemical and physical parameters, microbial community composition and the potential rates of nitrification, denitrification and nitrate ammonification were measured at two different depths (0–1 and 1–5 cm) after the acclimatization period to evaluate the role of roots. Results Vallisneria spiralis grew and assimilated pore water nutrients at the two organic matter levels and vegetated sediments had always nutrient-depleted porewaters as compared to bare sediments. Nitrifying microbes had a lower relative abundance and diversity compared to denitrifying bacteria. However, regardless of the organic content, in vegetated sediments nitrifiers were detected in deeper horizons as compared to bare sediments, where nitrification was confined near the surface. In contrast, potential denitrification rates were not affected by the presence of roots, but probably regulated by the presence of nitrate and by root-dependent nitrification. Potential nitrate ammonification rates were always much lower (