Reduction Of NO Research Articles

Investigating the efficacy of dapsone in treating sepsis induced by cecal ligation and puncture surgery in male mice.

Sepsis is a life-threatening condition caused by the body's response to an infection. Dapsone is a sulfone with antibiotic properties, and experimental evidence suggests it has significant anti-inflammatory and anti-oxidative stress effects. The objective of this study was to investigate the efficacy of dapsone in mice after CLP (cecal ligation and puncture) surgery, which is a model for inducing sepsis. The study divided animals into five groups: CLP, sham, and three groups receiving different doses of dapsone (0.5, 1, 2mg/kg). Sepsis was induced through CLP surgery, followed by dapsone administration. In each group, half of the mice were used to evaluate levels of various markers and pathological changes at 24h post-CLP, while the other half was used to record the mortality rates within 96h. The results showed that single-dose administration of dapsone at (0.5, 1, 2mg/kg) after CLP surgery improved survival compared to the CLP group. Dapsone was also associated with a significant reduction in pro-inflammatory cytokines TNF-α, IL-1β, IL-6, NO, and MPO, as well as lactate and creatinine serum levels. However, dapsone did not have a significant effect on urea serum levels. In conclusion, the data suggest that dapsone treatment leads to increased survival in septic mice after CLP, and due to its ability to reduce TNF-α, IL-1β, IL-6, MPO,and lactate levels, it has anti-inflammatory effects in sepsis. The sepsis treatment with dapsone in mice protects against inflammation and oxidative stress.

Two-Dimensional Bi2Se3 Nanosheets Synthesis for Efficient Electrocatalytic Production of Ammonia from Nitrate

Ammonia (NH3), a critical component for various industries, is produced through the Haber-Bosch process, which, despite its importance, is a significant source of carbon emissions and operates on a centralized model, emphasizing the need for innovative solutions to decarbonize and decentralize its production. Electrochemical nitrate (NO3–) reduction to NH3 presents a promising alternative to the Haber-Bosch process for NH3 synthesis, with the added advantage of transforming waste into a valuable resource while mitigating water pollution concerns. However, achieving a well-defined active center and catalytic selectivity in the electrochemically driven reaction remains a significant challenge. In this study, we successfully fabricated a highly selective and active 2D Bi2Se3 catalyst, which demonstrated better performance in reducing NO3– to NH3 with a Faradaic efficiency (FE) of approximately 80% (−0.3V (RHE)) and a significant yield rate of 45mgh−1mgcat−1 (0.46 mmolh−1cm−2). Furthermore, the fabricated material exhibited exceptional stability and durability, maintaining a high NO3– reduction of 80% FE even after 10 consecutive cycles of extended use and continuous operation, demonstrating its remarkable resilience and reliability. Our findings show that the prepared catalyst selectively promotes the electrochemical reduction of NO3– to NH3 while suppressing the competing hydrogen evolution reaction (HER). The charge density profile indicates a pronounced charge localization around the Se atoms, implying that the Se active sites in the 2D Bi2Se3 catalyst act as the active center for the NO3– reduction mechanism, playing a crucial role in facilitating the reaction kinetics.

Damage Evolution and NOx Photocatalytic Degradation Performance of Nano-TiO2 Concrete Under Freeze–Thaw Cycles

The internal pore structure of nano-TiO2 concrete deteriorates gradually during freeze–thaw (F–T) cycles. The deterioration process can reveal the F–T damage mechanism and the deterioration law of photocatalytic performance. The evolution law of the pore structure of nano-TiO2 concrete during F–T damage was investigated. Moreover, this paper defined the microscopic F–T damage factor based on porosity and fractal dimension. The results showed that a 2% dosage of nano–TiO2 concrete had better frost resistance and lower porosity in this experiment. Its porosity only increased by 13.3% after 200 F–T cycles, which was much smaller than that of ordinary concrete. Furthermore, the presence of nano-TiO2 enhanced the volume fractal dimension of concrete pores larger than 100 nm, increasing the complexity of the pore structure and contributing to improved frost resistance. F–T damage led to a decrease in the photocatalytic performance of nano–TiO2 concrete. Still, it helped the nitrate on the surface of the concrete to dissolve and disappear more quickly under rainwater washout. Finally, a thermodynamic theory-based concrete F–T damage correction model was constructed, and the model was used to predict F–T damage values for some scholars. The results showed that the correlation between the model values and the experimental values was more than 0.95, which could accurately reflect the degree of F–T damage of concrete. In addition, a prediction model of photocatalytic NO reduction by nano-TiO2 concrete based on microscopic damage factor was established. It provides a theoretical basis for the application of nano-TiO2 concrete in the field of gas pollutant treatment.

Developing Robust Ceria-Supported Catalysts for Catalytic NO Reduction and CO/Hydrocarbon Oxidation

Developing Robust Ceria-Supported Catalysts for Catalytic NO Reduction and CO/Hydrocarbon Oxidation

Regulation of Coordination Environment Over Cu Sites: Triggering the Efficient Selective Catalytic Reduction of NOx Using NH3 as Reductant

Regulation of Coordination Environment Over Cu Sites: Triggering the Efficient Selective Catalytic Reduction of NO_x Using NH₃ as Reductant

Isolating Cu-Zn active-sites in Ordered Intermetallics to Enhance Nitrite-to-Ammonia Electroreduction

Electrocatalytic nitrite reduction to the valuable ammonia is a green and sustainable alternative to the conventional Haber-Bosch method for ammonia synthesis, while the activity and selectivity for ammonia production remains poor at low nitrite concentrations. Herein, we report a nanoporous intermetallic single-atom alloy CuZn (np/ISAA-CuZn) catalyst with completely isolated Cu-Zn active-sites, which achieves neutral nitrite reduction reaction with a remarkable NH3 Faradaic efficiency over 95% and the highest energy efficiency of ≈ 59.1% in wide potential range from −0.2 to −0.8 V vs. RHE. The np/ISAA-CuZn electrocatalyst was able to operate stably at 500 mA cm−2 for 220 h under membrane electrode assembly conditions with a stabilized NH3 Faraday efficiency of ~80% and high NO2‒ removal rate of ~100%. A series of in situ experimental studies combined with density functional theory calculations reveal that strong electronic interactions of isolated Cu-Zn active-sites altered the protonation adsorption species, effectively alleviating the protonation barrier of *NO2 and thus greatly facilitating the selective reduction of NO2− into NH3.

Reduction of Nitrite in an Iron(II)-Nitrito Compound by Thiols and Selenol Produces Dinitrosyl Iron Complexes via an {FeNO}7 Intermediate.

Reaction of an Fe(II) complex, [Fe(6-COO--tpa)]1+ (1), with PhE- and NO2- produced [Fe(6-COO--tpa)(EPh)] (E = S, 2a; Se, 3) and [Fe(6-COO--tpa)(κ2-O,O'-NO2)] (4), respectively (6-COOH-tpa is bis(2-pyridylmethyl)(6-carboxyl-2-pyridylmethyl)amine). Treatment of 4 with 2 equiv of PhEH (E = S, Se) produced NO in ∼40% yields, respectively, along with 1 and the DNICs, [Fe(EPh)2(NO)2]1- (E = S, Se). Treatment of 4 with excess PhEH produced NO in similar yields, while 4 was converted to the same DNICs and 2a/3 (instead of 1). The DNICs have been proposed to be generated via the reaction of PhE- with an in situ generated, unstable {FeNO}7 intermediate, [Fe(6-COO--tpa)(NO)]1+ (6), which has also been synthesized separately. Compound 6 reacts with PhS- to generate [Fe(SPh)2(NO)2]1-, thus supporting the proposed reaction pathway. Finally, while the treatment of two unique compounds, featuring inbuilt proton sources, [Fe(6-COO--tpa)(S-C6H4-p-COOH)] (7) and [Fe(6-COO--tpa)(S-C6H4-o-OH)] (8), with 0.5 and 1 equiv of NO2- could produce NO only in 8-26% yields, treatment of 4 with HS-C6H4-p-COOH and HS-C6H4-o-OH produced NO in much higher yields (65-77%). The combined results delineated the importance of coordination of NO2- for the proton-assisted reduction of NO2- to generate NO.

Direct parallel electrosynthesis of high-value chemicals from atmospheric components on symmetry-breaking indium sites

To tackle significant environmental and energy challenges from increased greenhouse gas emissions in the atmosphere, we propose a method that synergistically combines cost-efficient integrated systems with parallel catalysis to produce high-value chemicals from CO2, NO, and other gases. We employed asymmetrically stretched InO5S with symmetry-breaking indium sites as a highly efficient trifunctional catalysts for NO reduction, CO2 reduction, and O2 reduction. Mechanistic studies reveal that the symmetry-breaking at indium sites substantially improves d-band center interactions and adsorption of intermediates, thereby enhancing trifunctional catalytic activity. Employed in a flow electrolysis system, the catalyst achieves continuous and flexible production of NH3, HCOO-, and H2O2, maintaining over 90% Faradaic efficiency at industrial scales. Notably, the parallel electrolysis device reported in this study effectively produces high-value products like NH4COOH directly from greenhouse gases in pure water, offering an economically efficient solution for small molecule synthesis and unique insights for the sustainable conversion of inexhaustible gases into valuable products. Therefore, this work possesses considerable potential for future practical applications in sustainable industrial processes.

Recent Advances in NO Reduction with NH3 and CO Over Cu-Ce Bimetallic and Derived Catalysts

Sintering flue gas contains significant amounts of harmful gases, such as carbon monoxide and nitrogen oxides (NOx), which pose severe threats to the ecological environment and human health. Selective catalytic reduction (SCR) technology is widely employed for the removal of nitrogen oxides, with copper-cerium-based bimetallic catalysts and their derivatives demonstrating excellent catalytic efficiency in SCR reactions, primarily due to the significant synergistic effect between copper and cerium. This paper summarizes the main factors affecting the catalytic performance of Cu-Ce-based bimetallic catalysts and their derivatives in the selective catalytic reduction of ammonia and carbon monoxide. Key considerations include various preparation methods, doping of active components, and the effects of loading catalysts on different supports. This paper also analyzes the influence of surface oxygen vacancies, redox capacity, acidity, and specific surface area on catalytic performance. Additionally, the anti-poisoning performance and reaction mechanisms of the catalysts are discussed. Finally, the paper proposes strategies for designing high-activity and high-stability catalysts, considering the development prospects and challenges of Cu-Ce-based bimetallic catalysts and their derivatives, with the aim of providing theoretical guidance for optimizing Cu-Ce-based catalysts and promoting their industrial applications.

Factors Determining the Selectivity of NO Reduction Catalyzed by Copper-Vanadium Oxide Cluster Anions Cu2VO3-5.

Catalytic NO reduction by CO is imperative to satisfy the increasingly rigorous emission regulations. Identifying the structural characteristic of crucial intermediate that governs the selectivity of NO reduction is pivotal to having a fundamental understanding on real-life catalysis. Herein, benefiting from the state-of-the-art mass spectrometry, we demonstrated experimentally that the Cu2VO3-5 - clusters can mediate the catalysis of NO reduction by CO, and two competitive channels to generate N2O and N2 can co-exist. Quantum-chemical calculations were performed to rationalize this selectivity. The formation of the ONNO unit on the Cu2 dimer was demonstrated to be a precursor from which two pathways of NO reduction start to emerge. In the pathway of N2O generation, only the Cu2 dimer was oxidized and the VO3 moiety functions as a "support", while both moieties have to contribute to anchor oxygen atoms from the ONNO unit and then N2 can be generated. This finding displays a clear picture to elucidate how and why the involvement of VO3 "support" can regulate the selectivity of NO reduction.

Selective catalytic reduction of NO with NH3 over HZSM-5/CeO2 hybrid catalysts: Relationship between acid structure and reaction mechanism

CeO2 is active in the NH3 selective catalytic reduction of NO (NH3-SCR) reaction due to its excellent redox properties. However, the low surface acidity of CeO2 limits its NH3-SCR activity. In this study, highly active HZSM-5-modified HZSM-5/CeO2 (Z/Ce) mixed oxide catalysts were prepared by a simple physical milling method. The HZSM-5 modification stimulated many thermally stable Brønsted-acid structures and high oxygen mobility on the surface of the Z/Ce catalysts, promoting the acid cycling pathways driven by redox macrocycles, and accelerating NO removal. The NO conversion of 25Z/Ce at 200–400 °C is about 34.8 %-62.3 % higher than that of CeO2. A series of physicochemical and in situ interfacial reactions were analyzed to explore the medium- and high-temperature reaction mechanism on the CeO2 surface. The Eley-Rideal reaction mechanism on the Lewis-acid structure with NO(g) as the reactant is deduced. When HZSM-5 modified CeO2, more NO was activated to NO2(g) on the surface of the Z/Ce catalyst at medium and high temperatures (300 °C). This significantly enhanced the Eley-Rideal reaction mechanism with NO2(g) as the main reactant on the Brønsted-acid structure as well as the occurrence of the “Fast-SCR” reaction. This work provides a simple method to improve the performance of CeO2 in the NH3-SCR reaction and elucidates the reaction mechanism.

Effect of modified Fe2O3/activated carbon catalysts for low-temperature CO selective catalytic reduction of NOx in underground diesel vehicle exhaust

The elimination of CO and NOx has practical significance for the control of exhaust pollutants from underground diesel vehicles. Catalytic reduction of NO by CO (CO-SCR) using activated carbon (AC) catalysts is considered a cost-effective and environmentally friendly denitrification method. In this study, Fe2O3/AC-based catalysts were prepared using an impregnation method and modified with different metals to investigate their impact on catalyst performance. The results demonstrated that the catalyst exhibited the highest denitrification efficiency when loaded with 10 % Fe. The Mn-doped 10Fe/AC catalyst exhibited the best catalytic performance, with the highest NO conversion of 97.5 % and CO removal rate of 83.3 % at 240 °C. The effects of loading Mn, Ce, and La on the physical and chemical properties of the catalysts were analyzed using various characterization tools, and the reaction mechanism of the catalysts was investigated by in situ DRIFTS technique. The findings revealed that the strong synergistic interaction occurring between Mn and Fe led to an increase in the surface-adsorbed oxygen (Oα) and Fe3+, which produced more oxygen vacancies on the catalyst, thus improving the redox properties. The in-situ DRIFT results indicated that the addition of Mn enhanced the adsorption capacity of active NO and CO. For the CO-SCR reaction on Fe-Mn/AC catalyst, the E-R mechanism was followed at low temperature and the L-H mechanism was followed at high temperature.

The Effect of Intramolecular Proton Transfer on the Mechanism of NO Reduction to N2O by a Copper Complex: A DFT Study.

DFT calculations were performed to explore the mechanism underlying the reduction of NO to N2O by a CuI complex. A nitrosyl complex reacts with another NO molecule and the CuI complex, leading to the formation of a dicopper-hyponitrite complex (Cu2N2O2). The first steps follow a common pathway until the formation of the intermediate [CuII-N2O2]+, after which the reaction pathway diverges into three Cu2N2O2 species: κ2-N,N', κ2-O,O', and κ3-N,O,O'. These species yield different products along their respective reaction pathways. In the case of the κ2-N,N' and κ3-N,O,O' species, the subsequent steps involve a methanol-mediated proton transfer and N-O bond cleavage, resulting in the generation of N2O and [CuII-OH]+. Conversely, for the κ2-O,O' species, two proton transfers occur without N-O bond cleavage, leading to the formation of H2N2O2 and [CuII]2+. H2N2O2 spontaneously converts into N2O and H2O. These computational results elucidate how the coordination mode of hyponitrite influences reactivity and provide insights into NO reduction via proton transfer. Notably, switching of the N2O2 coordination mode to metal ions from N to O was not required, offering insights for more efficient NO reduction strategies in the future.

Methane-driven microbial nitrous oxide production and reduction in denitrifying anaerobic methane oxidation cultures

Methane (CH4) and nitrous oxide (N2O) are two important greenhouse gases (GHGs), and it is very important to achieve the reduction of both gases in the case of increasingly serious climate change. The study confirms the simultaneous mitigation of potent GHGs N2O and CH4 in denitrifying anaerobic methane oxidation (DAMO) enrichment, supplementing the understanding that DAMO microorganisms do not produce and reduce N2O. We observed rapid accumulation and consumption of N2O in DAMO cultures subjected to high nitrate and nitrite loadings. Moreover, when N2O served as the sole electron acceptor, a significant correlation was found between the flux of N2O reduction and CH4 oxidation. Inhibition of the particulate methane monooxygenase (pMMO) led to a notable decrease of 95% in N2O reduction and 50% in CH4 oxidation. Metagenomic analysis revealed that Candidatus Methanoperedens and Candidatus Methylomirabilis were the dominant genera, with all functional genes related to denitrification and methane oxidation identified, including NO reductase (nor) of Ca. Methylomirabilis. Transcriptomic analysis further confirmed that the transcripts of nor were one order of magnitude higher than other functional genes. These results indicate that when the substrate NO2- surpasses the dismutation capacity of NO dismutase (nod), DAMO bacteria can alternatively induce nor to reduce NO to N2O. However, considering that N2O reductase (nosZ) is still missing in Ca. Methylomirabilis, the partner Methyloversatilis may be responsible for N2O reduction. Our results provide new insights into the link between GHG emissions in DAMO systems under anaerobic conditions.

Boron-modified Ce-Zr mixed oxide catalysts for improved low-temperature NO reduction

Boron-modified Ce-Zr mixed oxide catalysts for improved low-temperature NO reduction

Seasonal Variation in Flow and Metabolic Activity Drive Nitrate and Carbon Supply and Demand in a Temperate Agricultural Stream

AbstractIn‐stream biogeochemical processing, typically associated with base flow conditions, has recently been assessed at higher discharges, aided by high frequency monitoring. However, the potential for nutrient and carbon processing is still largely unknown in streams impacted by agriculture, representing major pathways for eutrophication and diffuse pollution. In this study, we measured solute concentrations and gross primary productivity (GPP) and ecosystem respiration (ER) to infer nitrate (NO3−) and dissolved organic carbon (DOC) supply and demand across contrasting hydrological conditions. As expected, solute supply greatly surpassed in‐stream biological demand for both NO3− and DOC for intermediate to large discharges. However, during four consecutive weeks in summer, lowered NO3− supply and high metabolic activity led to a 60% and 31% reduction in stream NO3− and DOC export. We also compared metabolism‐discharge versus solute concentration‐discharge patterns during storm events to better understand biogeochemical responses to high flows. Metabolic rates showed a contrasting response to storm events: ER increased while GPP decreased following declines in NO3− concentrations. The positive correlation between GPP and NO3− concentrations suggests that GPP suppression can be partially attributed to decreased NO3− availability during storm events. This study supports the idea that agricultural streams have a limited capacity to biologically process DOC and NO3−. However, it also emphasizes that the balance between supply and demand can vary from severe saturation to limitation, depending on seasonal fluctuations in discharge and metabolic activity, highlighting the crucial role of mitigating pollution at its source during hydrologically active periods to improve water quality.

Modifying functional groups of straw-based hydrogel provide soil N2O mitigation potential by complete denitrification

Farmed soil is considered to contribute more than 60% anthropogenic N2O emission which plays critical role in global warming potential. Straw-based hydrogels with abundant functional groups are commonly used in environmental and agronomic applications primarily as adsorbents. Those functional groups could mediate electron transfer in the process of adsorbates and might also regulate N2O emission. However, it was still unclear whether and how these functional groups affect the process. To address this knowledge gap, we employed spectral analysis and a robotized incubation system to determine mechanisms of different functional groups in influencing soil N2O. The results indicated that the straw-based hydrogel was capable of significantly reducing the emission of N2O in denitrification, and the electrochemical properties of the hydrogel had promoting effect of the microbial genetic potential for N2O reduction. Specifically, carboxymethyl (R-COO) and primary amine groups (R-NH2) promoted complete denitrification through electron supply. Furthermore, R-NH2 had a significant negative correlation with N2O emissions. To further verify the role of specific structures and functional groups in denitrification, we conducted an experiment using pure lignin as a template. This experiment resulted in an increase in R-NH2 content to 13.2% and a decrease in N2O emissions by 49.1% compared with straw hydrogel. These results prove the feasibility of straw-based hydrogel as a redox system to accelerate complete denitrification, and the electron-donating functional groups were significantly related to the reduction rate of N2O. Finally, based on these mechanisms, functional group targeted grafting technology was proposed to improve its ability to mitigate N2O emission reduction.

One-ElectronNO to N2O Pathways via Heme Models and Lewis Acid: Metal Effectsand Differences from the Enzymatic Reaction.

Some pathogens use heme-containing nitric oxide reductases (NORs) to reduce NO to N2O as their defense mechanism to detoxify NO and reduce nitrosative stress. This reduction is also significant in the global N cycle. Our previous experimental work showed that Fe and Co porphyrin NO complexes can couple with external NO to form N2O when activated by the Lewis acid BF3. A key difference from conventional two-electron enzymatic reaction is that one electron is sufficient. However, a complete understanding of the entire reaction pathways and the more favorable reactivity for Fe remains unknown. Here, we present a quantum chemical study to provide such information. Our results confirmed Fe's higher experimental reactivity, showing advantages in all steps of the reaction pathway: easier metal oxidation for NO reduction and N-O cleavage as well as a larger size to expedite the N/O coordination mode transition. The Co system, with a similar product energy as the enzyme, shows potential for further development in catalytic NO coupling. This work also offers the first evidence that this new one-electron NO reduction is both kinetically competitive and thermodynamically more favorable than the native pathway, supporting future initiatives in optimizing NO reduction agents in biology, environment, and industry.

Modulating charge transfer and constructing synergistic bimetallic active sites for CO-SCR reactions in inverse spinel

The selective catalytic reduction of NO by CO (CO-SCR) are frequently catalyzed by spinel due to its exceptional stability and redox capabilities. In this research, a ternary metal-based inverse spinel catalyst Cu0.67Mn0.33Fe2O4 was synthesized utilizing the glycerol self-templating technique. Some Fe3+ (Fe3+Td) sites are transferred to vacant octahedral sites through the occupancy of tetrahedral sites by Mn species. Mn3+ (Mn3+Td) sites synergistically interact with Cu2+ and Fe3+ ions on the octahedral sites to promote charge transfer, producing numerous oxygen-defective and highly mobile oxygen species and constructing Cu+-Ov-Fe2+ active sites on the surface. Various characterizations demonstrated that Cu+-Ov-Fe2+ has greater catalytic activity, resistance to alkali metals, and water toxicity than the Cu2+-Ov-Fe2+ active site of CuFe2O4. In situ DRIFTS further revealed the reaction mechanism of the ternary metal-based inverse spinel catalyst, and this study provides novel perspectives on the development of Cu-based catalysts for CO-SCR.

Low temperature sintering flue gas NH3-SCR denitrification mechanism of embedded 7Mn3Ce/AC catalyst

Friction of catalyst in practical application and transportation leads to the metal oxides shedding, thus diminishing the lifetime. In order to inhibit the active component fallout, a series of embedded catalysts were prepared by activated carbon (AC) fabrication from coal as based, which were designed to remove NOx from sinter flue gas. Research results demonstrated that the denitrification activity of 7Mn3Ce/AC catalyst reached 81.3 % at 180 °C, and still maintained stable NO conversion after 44 h. MnO2 and CeO2 were added in catalyst could increase the Oα proportion, leading to an improvement the mobility of oxygen. Moreover, the formation of oxygen vacancies by Oβ in cerium oxide was facilitated by a high relative ratio of Ce3+, and Mn4+ favorable redox properties promoted the reduction of NO to N2, which advantaged the denitrification process. Furthermore, abundant Lewis acid and Brønsted acid sites were instrumental in the accumulation of NH3 on the catalyst surface. The reaction pathway of 7Mn3Ce/AC catalyst followed the E-R and L-H mechanisms.