A reduced combustion mechanism of ammonia/diesel optimized with multi-objective genetic algorithm

For the deep understanding on combustion of ammonia/diesel,this study develops a reduced mechanism of ammonia/diesel with 227 species and 937 reactions.The sub-mechanism on ammonia/interactions of N-based and C-based species(N—C)/NOx is optimized using the Non-dominated Sorting Genetic Algorithm II(NSGA-II)with 200 generations.The optimized mechanism(named as 937b)is validated against combustion characteristics of ammonia/methane(which is used to examine the accuracy of N—C interactions)and ammonia/diesel blends.The ignition delay times(IDTs),the laminar flame speeds and most of key intermediate species during the combustion of ammonia/methane blends can be accurately simulated by 937b under a wide range of conditions.As for ammonia/diesel blends with various diesel energy fractions,reasonable predictions on the IDTs under pressures from 1.0 MPa to5.0 MPa as well as the laminar flame speeds are also achieved by 937b.In particular,with regard to the IDT simulations of ammonia/diesel blends,937b makes progress in both aspects of overall accuracy and computational efficiency,compared to a detailed ammonia/diesel mechanism.Further kinetic analysis reveals that the reaction pathway of ammonia during the combustion of ammonia/diesel blend mainly differs in the tendencies of oxygen additions to NH_2 and NH with different equivalence ratios.

Solar hydrogen production from electrochemical ammonia splitting powered by a single perovskite solar cell

For carbon-free electrochemical fuel formation,the electrochemical cell must be powered by renewable energy.Obtaining solar-powered H_(2) fuel from water typically requires multiple photovoltaic cells and/or junctions to drive the water splitting reaction.Because of the lower thermodynamic requirements to oxidize ammonia compared to water,solar cells with smaller open circuit voltages can provide the required potential for ammonia splitting.In this work,a single perovskite solar cell with an open-circuit potential of 1.08 V is coupled to a 2-electrode electrochemical cell employing hybrid electroanodes functionalized with Ru-based molecular catalysts.The device is active for more than 30 min,producing N_(2) and H_(2) in a 1:2.9 ratio with 89%faradaic efficiency with no external applied bias.This work illustrates that hydrogen production from ammonia can be driven by conventional semiconductors.

Integration of morphology and electronic structure modulation on cobalt phosphide nanosheets to boost photocatalytic hydrogen evolution from ammonia borane hydrolysis

The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy.Ammonia borane(AB)has regarded as a competitive candidate for chemical hydrogen storage.However,developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge.Herein,cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure,and function as hydrogen evolution photocatalysts.Impressively,the Co_(2)P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min^(-1),outperforming most of the noble-metal-free catalysts reported to date.This remarkable performance is attributed to its desired nanosheets structure,featuring with high specific surface area,abundant exposed active sites,and short charge diffusion paths.Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond.

Exploring nitrogen reduction reaction mechanisms in electrocatalytic ammonia synthesis:A comprehensive review

The electrochemical nitrogen reduction reaction(eNRR)holds significant promise as a sustainable alternative to the conventional large-scale Haber Bosch process,offering a carbon footprint-free approach for ammonia synthesis.While the process is thermodynamically feasible at ambient temperature and pressure,challenges such as the competing hydrogen evolution reaction,low nitrogen solubility in electrolytes,and the activation of inert dinitrogen(N_(2))gas adversely affect the performance of ammonia production.These hurdles result in low Faradaic efficiency and low ammonia production rate,which pose obstacles to the commercialisation of the process.Researchers have been actively designing and proposing various electrocatalysts to address these issues,but challenges still need to be resolved.A key strategy in electrocatalyst design lies in understanding the underlying mechanisms that govern the success or failure of the electrocatalyst in driving the electrochemical reaction.Through mechanistic studies,we gain valuable insights into the factors affecting the reaction,enabling us to propose optimised designs to overcome the barriers.This review aims to provide a comprehensive understanding of the various mechanisms involved in eNRR on the electrocatalyst surface.It delves into the various mechanisms such as dissociative,associative,Mars-van Krevelen,lithium-mediated nitrogen reduction and surface hydrogenation mechanisms of nitrogen reduction.By unravelling the intricacies of eNRR mechanisms and exploring promising avenues,we can pave the way for more efficient and commercially viable ammonia synthesis through this sustainable electrochemical process by designing an efficient electrocatalyst.

Comprehensive understanding of the thriving electrocatalytic nitrate/nitrite reduction to ammonia under ambient conditions

Ammonia(NH_(3))is a multifunctional compound that is an important feedstock for the agricultural and pharmaceutical industries and attractive energy storage medium.At present,NH_(3)synthesis is highly dependent on the conventional Haber–Bosch process that operates under harsh conditions,which consumes large quantities of fossil fuels and releases a large amount of carbon dioxide.As an alternative,electrosynthesis is a prospective method for producing NH_(3)under normal temperature and pressure conditions.Although electrocatalytic nitrogen reduction to ammonia has attracted considerable attentions,the low solubility of N_(2)and high N≡N cracking energy render the achievements of high NH_(3) yield rate and Faradaic efficiency difficult.Nitrate and nitrite(NO_(x)^(-))are common N-containing pollutants.Due to their high solubilities and low dissociation energy of N=O,NO_(x)^(-)−are ideal raw materials for NH_(3) production.Therefore,electrocatalytic NO_(x)^(-)−reduction to NH_(3)(eNO_(x)RR)is a prospective strategy to simultaneously realise environmental protection and NH_(3) synthesis.This review offers a comprehensive understanding of the thriving eNO_(x)RR under ambient conditions.At first,the popular theory and mechanism of eNO_(x)RR and a summary of the measurement system and evaluation criteria are introduced.Thereafter,various strategies for developing NO_(x)−reduction catalysts are systematically presented and discussed.Finally,the challenges and possible prospects of electrocatalytic NO_(x)^(-1) reduction are outlined to facilitate energy-saving and environmentally friendly large-scale synthesis of NH_(3) in the future.

100 W-class green hydrogen production from ammonia at a dual-layer electrode containing a Pt-Ir catalyst for an alkaline electrolytic process

Ammonia allows storage and transport of hydrogen over long distances and is an attractive potential hydrogen carrier.Electrochemical decomposition has recently been used for the conversion of ammonia to hydrogen and is regarded as a future technology for production of CO_(2)-free pure hydrogen.Herein,a heterostructural Pt-Ir dual-layer electrode is developed and shown to achieve successful long-term operation in an ammonia electrolyzer with an anion exchange membrane(AEM).This electrolyzer consisted of eight membra ne electrode assemblies(MEAs)with a total geometric area of 200 cm~2 on the anode side,which resulted in a hydrogen production rate of 25 L h~(-1).We observed the degradation in MEA performance attributed to changes in the anode catalyst layer during hydrogen production via ammonia electrolysis.Furthermore,we demonstrated the relationship between the ammonia oxidation reaction(AOR)and the oxygen evolution reaction(OER).

Enhancing Green Ammonia Electrosynthesis Through Tuning Sn Vacancies in Sn‑Based MXene/ MAX Hybrids

Renewable energy driven N_(2) electroreduction with air as nitrogen source holds great promise for realizing scalable green ammonia production.However,relevant out-lab research is still in its infancy.Herein,a novel Sn-based MXene/MAX hybrid with abundant Sn vacancies,Sn@Ti_(2)CTX/Ti_(2)SnC–V,was synthesized by controlled etching Sn@Ti_(2)SnC MAX phase and demonstrated as an efficient electrocatalyst for electrocatalytic N2 reduction.Due to the synergistic effect of MXene/MAX heterostructure,the existence of Sn vacancies and the highly dispersed Sn active sites,the obtained Sn@Ti2CTX/Ti_(2)SnC–V exhibits an optimal NH_(3) yield of 28.4μg h^(−1) mg_(cat)^(−1) with an excellent FE of 15.57% at−0.4 V versus reversible hydrogen electrode in 0.1 M Na_(2)SO_(4),as well as an ultra-long durability.Noticeably,this catalyst represents a satisfactory NH3 yield rate of 10.53μg h^(−1) mg^(−1) in the home-made simulation device,where commercial electrochemical photovoltaic cell was employed as power source,air and ultrapure water as feed stock.The as-proposed strategy represents great potential toward ammonia production in terms of financial cost according to the systematic technical economic analysis.This work is of significance for large-scale green ammonia production.

The First Global Map of Atmospheric Ammonia(NH_(3)) as Observed by the HIRAS/FY-3D Satellite

Atmospheric ammonia(NH_(3)) is a chemically active trace gas that plays an important role in the atmospheric environment and climate change. Satellite remote sensing is a powerful technique to monitor NH_(3) concentration based on the absorption lines of NH_(3) in the thermal infrared region. In this study, we establish a retrieval algorithm to derive the NH_(3)column from the Hyperspectral Infrared Atmospheric Sounder(HIRAS) onboard the Chinese Feng Yun(FY)-3D satellite and present the first atmospheric NH_(3) column global map observed by the HIRAS instrument. The HIRAS observations can well capture NH_(3) hotspots around the world, e.g., India, West Africa, and East China, where large NH_(3) emissions exist. The HIRAS NH_(3) columns are also compared to the space-based Infrared Atmospheric Sounding Interferometer(IASI)measurements, and we find that the two instruments observe a consistent NH_(3) global distribution, with correlation coefficient(R) values of 0.28–0.73. Finally, some remaining issues about the HIRAS NH_(3) retrieval are discussed.

TiO2-PES Fibrous Composite Material for Ammonia Removal Using UV-A Photocatalyst

This study focused on the development and characterization of TiO2-PES composite fibers with varying TiO2 loading amounts using a phase inversion process. The resulting composite fibers exhibited a sponge-like structure with embedded TiO2 nanoparticles within a polymer matrix. Their photocatalytic performance for ammonia removal from aqueous solutions under UV-A light exposure was thoroughly investigated. The findings revealed that PeTi8 composite fibers displayed superior adsorption capacity compared to other samples. Moreover, the study explored the impact of pH, light intensity, and catalyst dosage on the photocatalytic degradation of ammonia. Adsorption equilibrium isotherms closely followed the Langmuir model, with the results indicating a correlation between qm values of 2.49 mg/g and the porous structure of the adsorbents. The research underscored the efficacy of TiO2 composite fibers in the photocatalytic removal of aqueous under UV-A light. Notably, increasing the distance between the photocatalyst and the light source resulted in de-creased hydroxyl radical concentration, influencing photocatalytic efficiency. These findings contribute to our understanding of TiO2 composite fibers as promising photocatalysts for ammonia removal in water treatment applications.

Recent development of catalytic strategies for sustainable ammonia production

Presently,ammonia is an ideal candidate for future clean energy.The Haber-Bosch process has been an essential ammonia production process,and it is one of the most important technological advancements since its invention,sustaining the explosive growth of military munitions industry and fertilizers in the first half of the 20th century.However,the process is facing great challenges:the growing need for ammonia and the demands of environmental protection.High energy consumption and high CO_(2) emissions greatly limit the application of the Haber-Bosch method,and increasing research efforts are devoted to"green"ammonia synthesis.Thermocatalytic,electrocatalytic,and photocatalytic ammonia production under mild conditions and the derived chemical looping and plasma ammonia production methods,have been widely developed.Electrocatalytic and photocatalytic methods,which use low fossil fuels,are naturally being considered as future directions for the development of ammonia production.Although their catalytic efficiency of ammonia generation is not yet sufficient to satisfy the actual demands,considerable progress has been made in terms of regulating structure and morphology of catalyst and improving preparation efficiency.The chemical looping approach of ammonia production differs from the thermocatalytic,electrocatalytic,and photocatalytic methods,and is the method of reusing raw materials.The plasma treatment approach alters the overall ammonia production approach and builds up a new avenue of development in combination with thermal,photocatalytic,and electrocatalytic methods as well.This review discusses several recent effective catalysts for different ammonia production methods and explores mechanisms as well as efficiency of these catalysts for catalytic N2fixation of ammonia.

Nanoengineering Metal–Organic Frameworks and Derivatives for Electrosynthesis of Ammonia

Electrocatalytic synthesis under mild conditions has become increasingly important as one of the practical alternatives for industrial applications,especially for the green ammonia(NH_(3))industry.A properly engineered electrocatalyst plays a vital role in the realization of superior catalytic performance.Among various types of promising nanomaterials,metal–organic frameworks(MOFs)are competitive candidates for developing efficient electrocatalytic NH_(3) synthesis from simple nitrogen-containing molecules or ions,such as N_(2) and NO_(3)^(−).In this review,recent advances in the development of electrocatalysts derived from MOFs for the electrosynthesis of NH_(3) are collected,categorized,and discussed,including their application in the N_(2) reduction reaction(NRR)and the NO_(3)^(−)reduction reaction(NO3RR).Firstly,the fundamental principles are illustrated,such as plausible mechanisms of NH_(3) generation from N_(2) and NO_(3)^(−),the apparatus of corresponding electrocatalysis,parameters for evaluation of reaction efficiency,and detection methods of yielding NH_(3).Then,the electrocatalysts for NRR processes are discussed in detail,including pristine MOFs,MOF-hybrids,MOF-derived N-doped porous carbons,single atomic catalysts from pyrolysis of MOFs,and other MOF-related materials.Subsequently,MOF-related NO3RR processes are also listed and discussed.Finally,the existing challenges and prospects for the rational design and fabrication of electrocatalysts from MOFs for electrochemical NH_(3) synthesis are presented,such as the evolution of investigation methods with artificial intelligence,innovation in synthetic methods of MOF-related catalysts,advancement of characterization techniques,and extended electrocatalytic reactions.

Sustainable Ammonia Synthesis from Nitrogen and Water by One-Step Plasma Catalysis

Sustainable ammonia synthesis at ambient conditions that relies on renewable sources of energy and feedstocks is globally sought to replace the Haber-Bosch process.Here,using nitrogen and water as raw materials,a nonthermal plasma catalysis approach is demonstrated as an effective powerto-chemicals conversion strategy for ammonia production.By sustaining a highly reactive environment,successful plasma-catalytic production of NH_(3) was achieved from the dissociation of N_(2) and H_(2)O under mild conditions.Plasma-induced vibrational excitation is found to decrease the N_(2) and H_(2)O dissociation barriers,with the presence of matched catalysts in the nonthermal plasma discharge reactor contributing significantly to molecular dissociation on the catalyst surface.Density functional theory calculations for the activation energy barrier for the dissociation suggest that ruthenium catalysts supported on magnesium oxide exhibit superior performance over other catalysts in NH_(3) production by lowering the activation energy for the dissociative adsorption of N_(2) down to 1.07 eV.The highest production rate,2.67 mmol gcat.^(-1) h^(-1),was obtained using ruthenium catalyst supported on magnesium oxide.This work highlights the potential of nonthermal plasma catalysis for the activation of renewable sources to serve as a new platform for sustainable ammonia production.

Significant reduction of ammonia emissions while increasing crop yields using the 4R nutrient stewardship in an intensive cropping system

Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Herein,we report the NH_3 emissions,crop yield and changes in soil fertility in a long-term trial with various fertilization regimes,to explore whether NH_3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs),and its interaction with the organic amendments (i.e.,manure and straw) in a wheat–maize rotation.Implementing the 4Rs significantly reduced NH_3 emissions to 6 kg N ha~(–1) yr~(–1) and the emission factor to 1.72%,without compromising grain yield (12.37 Mg ha~(–1) yr~(–1))and soil fertility (soil organic carbon of 7.58 g kg~(–1)) compared to the conventional chemical N management.When using the 4R plus manure,NH_3 emissions (7 kg N ha~(–1) yr~(–1)) and the emission factor (1.74%) were as low as 4Rs,and grain yield and soil organic carbon increased to 14.79 Mg ha~(–1) yr~(–1) and 10.09 g kg~(–1),respectively.Partial manure substitution not only significantly reduced NH_3 emissions but also increased crop yields and improved soil fertility,compared to conventional chemical N management.Straw return exerted a minor effect on NH_3 emissions.These results highlight that 4R plus manure,which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.

Researchers Propose Electrodriven Chemical Looping Ammonia Synthesis Mediated by Lithium Imide

Ammo n i a(N H 3)i s a promising energy vector for the storage and utilization of renewable energies.Artificially synthesizing NH3 from its elements(Haber-Bosch process)requires harsh reaction conditions(400-500°C,10-30 MPa)because N2 is inert and nonpolar with a strong N≡N bond.The synthesis of NH3 under mild conditions is still challenging.

Bimetallic NiCo boride nanoparticles confined in a MXene network enable efficient ambient ammonia electrosynthesis

Ambient electrocatalytic nitrogen fixation is an emerging technology for green ammonia synthesis,but the absence of optimized,stable and performant catalysts can render its practical application challenging.Herein,bimetallic NiCo boride nanoparticles confined in MXene are shown to accomplish highperformance nitrogen reduction electrolysis.Ta king advantage of the synergistic effect in specific compositions with unique electronic d and p orbits and typical architecture of rich nanosized particles embedded in the interconnected conductive network,the synthesized MXene@NiCoB composite demonstrates extensive improvements in nitrogen molecule chemisorption,active area exposure and charge transport.As a result,optimal NH3 yield rate of 38.7μg h^(-1) mgcat^(-1).and Faradaic efficiency of 6.92%are acquired in0.1 M Na_(2)SO_(4) electrolyte.Moreover,the great catalytic performance can be almost entirely maintained in the cases of repeatedly-cycled and long-term electrolysis.Theoretical investigations reveal that the nitrogen reduction reaction on MXene@NiCoB catalyst proceeds according to the distal pathway,with a distinctly-reduced energy barrier relative to the Co2B counterpart.This work may inspire a new route towards the rational catalyst design for the nitrogen reduction reaction.

Epilepsy dynamics of an astrocyte-neuron model with ammonia intoxication

Experimental records in the cerebral cortex indicate that ammonia injection can lead to seizures. Considering that astrocytes play a vital role in mediating the uptake and absorption of ammonium ions in the extracellular space of the cortical circuit, we constructed a new astrocyte neuron coupling model, which is composed of a neuron and its astrocytes connected through the extracellular space, taking into account of the influence of extracellular ammonium ions. The numerical results verified the previous experimental observation that obtained epileptic firing modes of neurons and postsynaptic GABA reversal potential depolarization triggered by ammonia injection. In addition, we also determined the concentration–response relationship between the ammonium ion concentration and the time of entering epilepsy and predicted the threshold of the ammonium ion concentration for the onset of epilepsy.

Insight into the ammonia torrefaction and pyrolysis system of cellulose:Unraveling the evolution of chemical structure and nitrogen migration mechanism

This study aimed to investigate the mechanism of nitrogen doping,migration,and conversion during ammonia torrefaction and also explore the evolution law of the chemical structure of cellulose.The results showed that the ammonia torrefaction pretreatment could significantly optimize the distribution of nitrogen and oxygen elements in cellulose.The carbon skeleton first captured the active nitrogenous radicals to form-NHn-N,and pyridine-N and pyrrole-N originated from the conversion of-NHn-N.The existence of C=O played a major role in the immobilization of nitrogen.The nitrogen in bio-oil exists mainly in the form of five-and six-membered heterocycles.The correlation analysis showed that the main precursors for the formation of nitrogenous heterocyclic compounds were five-membered Oheterocyclic compounds.Finally,the product distribution characteristics in the torrefaction-pyrolysis systems were summarized,and the nitrogen doping and conversion mechanisms were proposed.This study expanded the boundaries of cellulose pretreatment and the production of high-value chemicals.

Modulating surface oxygen species via facet engineering for efficient conversion of nitrate to ammonia

Electrochemical reduction of nitrate,a common pollutant in aquatic environment,to valuable ammonia(NO3-RR) using renewably-sourced electricity has attracted widespread interests,with past efforts mainly focused on designing electrocatalysts with high activity and selectivity.The detailed correlation between catalyst properties and NO3-RR kinetics,nevertheless,is still not fully understood.In this work,we modulate the surface oxygen species of Cu_(2)O via facet engineering,and systematically study the impact of these oxygen species on the NO_(3)^(-)RR activity.Combining advanced spectroscopic techniques,densi ty fu n ctional theory calculations and molecular dynamics simulations,we find that while oxygen vacancies on Cu_(2)O(111) surface promote the adsorption of reactants and reaction intermediates,hydroxyl groups effectively inhibit the side reaction of hydrogen evolution and facilitate the hydrogenation process of NO3-RR.These two effects work in concert to render Cu_(2)O(111) facet the highest NO3-RR activity relative to those from other facets.Our study provides critical insights into the synergistic effect of exposed facets and surface oxygen species on heterogeneous catalysis,and offers a generalizable,facet engineeringbased strategy for improving the performance of a variety of electrocatalysts important for renewable energy conversion.

Overview of emerging catalytic materials for electrochemical green ammonia synthesis and process

The concept of“green-ammonia-zero-carbon emission”is an emerging research topic in the global community and many countries driving toward decarbonizing a diversity of applications dependent on fossil fuels.In light of this,electrochemical nitrogen reduction reaction(ENRR)received great attention at ambient conditions.The low efficiency(%)and ammonia(NH_(3))production rates are two major challenges in making a sustainable future.Besides,hydrogen evolution reaction is another crucial factor for realizing this NH_(3)synthesis to meet the large-scale commercial demand.Herein,the(i)importance of NH_(3)as an energy carrier for the next future,(ii)discussion with ENRR theory and the fundamental mechanism,(iii)device configuration and types of electrolytic systems for NH_(3)synthesis including key metrics,(iv)then moving into rising electrocatalysts for ENRR such as single-atom catalysts(SACs),MXenes,and metal–organic frameworks that were scientifically summarized,and(v)finally,the current technical contests and future perceptions are discussed.Hence,this review aims to give insightful direction and a fresh motivation toward ENRR and the development of advanced electrocatalysts in terms of cost,efficiency,and technologically large scale for the synthesis of green NH_(3).

Polyhedral silver clusters as single molecule ammonia sensor based on charge transfer-induced plasmon enhancement

The unique plasmon resonance characteristics of nanostructures based on metal clusters have always been the focus of various plasmon devices and different applications. In this work, the plasmon resonance phenomena of polyhedral silver clusters under the adsorption of NH_(3) , N_(2), H_(2), and CH_(4) molecules are studied by using time-dependent density functional theory. Under the adsorption of NH_(3) , the tunneling current of silver clusters changes significantly due to the charge transfer from NH_(3) to silver clusters. However, the effects of N_(2), H_(2), and CH_(4) adsorption on the tunneling current of silver clusters are negligible. Our results indicate that these silver clusters exhibit excellent selectivities and sensitivities for NH_(3) detection. These findings confirm that the silver cluster is a promising NH_(3) sensor and provide a new method for designing high-performance sensors in the future.