Since the proposal of achieving dual carbon goals,countries worldwide have been actively seeking next-generation energy technologies.Ammonia energy,particularly green ammonia,has recently become a focal point of globa...Since the proposal of achieving dual carbon goals,countries worldwide have been actively seeking next-generation energy technologies.Ammonia energy,particularly green ammonia,has recently become a focal point of global attention.The global green ammonia market is expected to grow from USD 17 million in 2021 to USD 5.415 billion by 2030,with a growth rate of 90.2%during this period.As a fossil energy company primarily focused on oil and natural gas,CNPC faces significant pressure to transition to low-carbon operations and achieve dual carbon goals.Keeping track of the current status and technological advancements in ammonia energy development can support CNPC in more effectively implementing its new energy strategy.展开更多
The oxophilicity of metal oxides is usually utilized to improve the ammonia oxidation reaction(AOR)activity of Pt-based catalysts.But the effect of strong interaction between Pt and metal oxides on AOR is not studied....The oxophilicity of metal oxides is usually utilized to improve the ammonia oxidation reaction(AOR)activity of Pt-based catalysts.But the effect of strong interaction between Pt and metal oxides on AOR is not studied.Herein,experimental and density functional theory calculation results indicate that a strong interaction is built between Pt and reducible CeOx by high-temperature reduction,which induces the electronic interaction due to the difference of work fu nction,then optimizing the competitive adsorption behavior of*OH and*NH_(3)based on hard-soft acid-base principle.Accordingly,the optimal sample achieves an AOR peak current density of 329 mA mg_(Pt)^(-1),which is 2.4 times that of Pt.Meanwhile,it also shows satisfied hydrogen evolution reaction activity with an overpotential of only 24.3 mV at-10 mA cm^(-2)due to the optimization of*H adsorption energy on Pt by CeO_(x).Therefore,this work proposes an AOR activity enhancement mechanism of metal oxides in terms of the strong interaction,and sheds light on developing effective bifunctional catalysts for ammonia electrolysis.展开更多
As an emergent energy carrier,ammonia benefits from a well-established industrial infrastructure for its transportation and production,positioning it as a promising candidate toward a carbon-free energy landscape.With...As an emergent energy carrier,ammonia benefits from a well-established industrial infrastructure for its transportation and production,positioning it as a promising candidate toward a carbon-free energy landscape.Within this context,the electrocatalytic ammonia oxidation reaction(AOR)is pivotal.Platinum(Pt),recognized as the most efficient AOR catalyst,has undergone extensive development over the years,yielding notable advancements across various domains,ranging from elucidating the reaction mechanism to exploring innovative materials.This review begins by elucidating the mechanism of ammonia oxidation,summarizing the evolution of the mechanism and the diverse intermediates identified through various detection methods.Subsequently,it outlines the research progress surrounding different Pt-based catalysts,followed by a discussion on standard protocols for electrochemical ammonia oxidation testing,which facilitates meaningful comparisons across studies and catalyzes the development of more efficient and potent catalysts.Moreover,the review addresses current challenges in ammonia oxidation and outlines potential future directions,providing a comprehensive outlook on the field.展开更多
The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by deposit...The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.展开更多
This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data fr...This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and 2020.The spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural activities.NH_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to 2020.The highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to 2020.Agricultural emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban zones.Regions within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)VCDs.The rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem model.The concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)VCDs.This emphasizes the crucial role of environmental policies targeting the reduction of these acidic gases.Effective emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.展开更多
Electrocatalytic nitrate reduction reaction (NO_(3)-RR) to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution issues.We report a CuO nanoparticles in...Electrocatalytic nitrate reduction reaction (NO_(3)-RR) to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution issues.We report a CuO nanoparticles incorporated on nitrogen-doped porous carbon (CuO@NC) catalyst for NO_(3)-RR.Part of Cu(Ⅱ) is reduced to Cu(Ⅰ) during the NO_(3)-RR process to construct Cu(Ⅰ)-Cu(Ⅱ) pairs,confirmed by in situ X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.Density functional theory (DFT) calculations indicated that the formation of Cu(Ⅰ) could provide a reaction path with smaller energy barrier for NO_(3)-RR,while Cu(Ⅱ) effectively suppressed the competition of hydrogen evolution reaction (HER).As a result,CuO@NC catalyst achieved a Faradaic efficiency of 84.2% at -0.49 V versus reversible hydrogen electrode (RHE),and a NH_(3)yield rate of 17.2 mg h^(-1)mg^(-1)cat.at -0.79 V vs.RHE,higher than the HaberBosch process (<3.4 g h^(-1)g^(-1)cat.).This work may open a new avenue for effective NO_(3)-RR by modulating oxidation states.展开更多
Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as...Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as the strongly enhanced synergistic interactions between Pt and Co atoms,the obtained Pt-on-Co/C400 catalysts exhib-ited excellent catalytic activity toward the hydrolysis of ammonia borane with an extremely high turnover frequency(TOF)value of 3022 min^(-1)at 303 K.Durability test indicated that the obtained Pt-on-Co/C400 catalysts possessed high catalytic stability,and there were no changes in the catalyst structures and catalytic activities after 10 cycles.展开更多
Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen producti...Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts.In this work,it is found that the prepared Raney Ni W-r treated with high concentration of NaOH(6.25 mol/L)at 110℃exhibited excellent catalytic performance for AB hydrolysis at room temperature.The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials,even higher than that of the 20%Pt/C catalyst.Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency(TOF)value is as high as 51.42 min-1.Owing to its high density and magnetic properties,the catalyst is very easy for magnetic separation.Furthermore,possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed.As a well-established industrial catalyst,Raney Ni has been prepared on a large scale at low cost.This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.展开更多
In recent years,photocatalytic N_(2) reduction for ammonia synthesis at room temperature and atmospheric pressure has gradually become a research hotspot,exhibiting extremely high development potential.However,the low...In recent years,photocatalytic N_(2) reduction for ammonia synthesis at room temperature and atmospheric pressure has gradually become a research hotspot,exhibiting extremely high development potential.However,the low photogenerated charge separation efficiency and the lack of effective active sites seriously constrain the reaction efficiencies of semiconductor photocatalysts for N_(2) reduction of ammonia synthesis.Therefore,the rational design of catalytic materials is the key to enhance the photocatalytic N_(2) reduction reaction of ammonia synthesis.Transition metal Ru as the active center not only accelerates the adsorption and activation of N_(2) molecules,but also has good selectivity for N_(2) reduction.Moreover,the interaction between the metal and the support can effectively regulate the electronic structure of the active site,accelerate the photogenerated electron transfer,and significantly enhance the photocatalytic activity.Based on this,this review systematically investigates the Ru co-semiconductors to realize efficient photocatalytic N_(2) reduction for ammonia synthesis,and introduces its basic principles.Specifically,the Ru co-semiconductor photocatalytic material systems are introduced,such as TiO2-based,g-C3N4-based,and metal oxide materials,including the design of catalysts,crystal structures,and other characteristics.In addition,the modification strategies of photocatalytic N_(2) reduction ammonia synthesis materials are also presented,including loading/doping,defect engineering,construction of heterojunctions,and crystal surface modulation.Furthermore,the progress and shortcomings of the application of Ru co-semiconductors in these processes are summarized and comprehensively discussed,and the future outlook of Ru co-semiconductors in photocatalytic N_(2) reduction ammonia synthesis applications is proposed.展开更多
This work investigates the potential of low-pressure,medium-speed dual-fuel engines for cleaner maritime transportation.The thermodynamic performance of these engines is explored using three alternative fuels:liquefie...This work investigates the potential of low-pressure,medium-speed dual-fuel engines for cleaner maritime transportation.The thermodynamic performance of these engines is explored using three alternative fuels:liquefied natural gas(LNG),methanol,and ammonia.A parametric analysis examines the effect of adjustments to key engine parameters(compression ratio,boost pressure,and air-fuel ratio)on performance.Results show an initial improvement in performance with an increase in compression ratio,which reaches a peak and then declines.Similarly,increases in boost pressure and air-fuel ratio lead to linear performance gains.However,insufficient cooling reduces the amount of fuel burned,which hinders performance.Exergy analysis reveals significant exergy destruction within the engine,which ranges from 69.96%(methanol)to 78.48%(LNG).Notably,the combustion process is the leading cause of exergy loss.Among the fuels tested,methanol exhibits the lowest combustion-related exergy destruction(56.41%),followed by ammonia(62.12%)and LNG(73.77%).These findings suggest that methanol is a promising near-term alternative to LNG for marine fuel applications.展开更多
To meet the demand for air-breathing power for wide-range vehicles at Mach 0–10,two thermal cycles with ammonia as the fuel and coolant were analyzed,namely the precooled rocket-turbine cycle(PC-RT)and the precooled ...To meet the demand for air-breathing power for wide-range vehicles at Mach 0–10,two thermal cycles with ammonia as the fuel and coolant were analyzed,namely the precooled rocket-turbine cycle(PC-RT)and the precooled gas-turbine cycle.Firstly,the operating modes of the precooled cycle engines were divided into turbine mode,precooling mode,and ramjet mode.Secondly,a fluid-structure coupling heat transfer program was used to evaluate the cooling effects of different fuels on the incoming high-temperature air.The result shows that the equivalent heat sink of ammonia is higher than that of other fuels and can meet the cooling requirement of at least Mach 4 in the precooling mode.Thirdly,the performance of the PC-RT in the turbine and precooling modes was compared at Mach 2.5.The result shows that air precooling alleviates the restriction of the pumping pressure on the minimum requiredβand improves the specific thrust within a reasonable range ofβ.Fourthly,the performance of the precooled cycle engines was compared when using different fuels.The result shows that the specific thrust of ammonia is greater than that of other fuels,and the performance advantages of ammonia are the most obvious in the precooling mode due to its highest equivalent heat sink.To sum up,the precooled cycle engines with ammonia as the fuel and coolant presented in this study have the advantages of no carbon emissions,low cost,high specific thrust,and no clogging of the cooling channels by cracking products.They are suitable for applications such as the first-stage power of the two-stage vehicle,and high Mach numbers air-breathing flight.展开更多
The electrochemical nitrogen reduction reaction(eNRR)presents a sustainable alternative to the energy-intensive Haber-Bosch process for ammonia(NH_(3))production.This review examines the fundamental principles of eNRR...The electrochemical nitrogen reduction reaction(eNRR)presents a sustainable alternative to the energy-intensive Haber-Bosch process for ammonia(NH_(3))production.This review examines the fundamental principles of eNRR,emphasizing the critical roles of proton-exchange membranes and electrolytes in facilitating efficient nitrogen(N_(2))reduction.Special attention is given to single-atom catalysts(SACs),highlighting their unique structural and electronic properties that contribute to enhanced catalytic performance.The discussions encompass SACs based on precious metals,non-precious metals,and non-metallic materials,delving into their synthesis methods,coordination environments,and activity in the eNRR.This review also elucidates current challenges in the field and proposes future research directions aimed at optimizing SACs design to enhance eNRR efficiency.展开更多
Blocking the development of edible mushrooms will affect the production cycle and yield of fruiting bodies.Phenylalanine ammonia lyase(PAL,EC 4.3.1.24.)is an enzyme that catalyzes the deamination of phenylalanine to f...Blocking the development of edible mushrooms will affect the production cycle and yield of fruiting bodies.Phenylalanine ammonia lyase(PAL,EC 4.3.1.24.)is an enzyme that catalyzes the deamination of phenylalanine to form trans-cinnamic acid.Previous studies have shown that a decrease in pal1 gene transcription delays fruiting body development in Pleurotus ostreatus.Herein,we used wild type(WT)and RNA interference(RNAi)strains to study the molecular regulation of pal1 by RNA sequencing and Agrobacterium-mediated genetic transformation.Our results showed that interference with the pal1 gene resulted in reductions in the total PAL enzyme activity and the total phenol content,as well as an increase in the intracellular H_(2)O_(2)content.RNA-Seq data demonstrated that the significantly enriched KEGG terms were mainly related to the peroxisome pathway,MAPK signaling pathway-yeast and three other pathways,and the catalase(CAT)gene cat1 is also involved in multiple pathways that were enriched above.Exogenous H_(2)O_(2)significantly enhanced the transcription of the cat1 gene and elevated total CAT enzymatic activity.Moreover,the levels of cat1 gene transcription and the total CAT enzymatic activity in the RNAi-pal1 strains gradually become closer to those in the WT strain through the removal of H_(2)O_(2),which indicated that pal1 regulated the expression of cat1 by affecting the intracellular H_(2)O_(2)content.Finally,the overexpression of the cat1 gene in P.ostreatus caused growth retardation,especially during the process of primordia formation.In conclusion,this study demonstrated that PAL1 affects cat1 gene expression through the signaling molecule H_(2)O_(2)and regulates the development of P.ostreatus.The findings of this study enhance our understanding of the molecular developmental mechanism of edible mushrooms.展开更多
The electrochemical conversion of toxic nitrite(NO_(2)-)is a promising approach for the simultaneous removal of nitrogen contaminants and synthesis of ammonia(NH_(3)).In this study,we present the Er-doping-induced ele...The electrochemical conversion of toxic nitrite(NO_(2)-)is a promising approach for the simultaneous removal of nitrogen contaminants and synthesis of ammonia(NH_(3)).In this study,we present the Er-doping-induced electronic modulation of CoP integrated with nitrogen-doped carbon(CN)nanosheets supported on a titanium mesh(Er-CoP@NC/TM)for the electrocatalytic NO_(2)-reduction reaction(eNO_(2)-RR)for NH_(3)synthesis.The catalyst demonstrates a high Faraday efficiency of 97.08±2.22%and a high yield of 2087.60±17.10μmol h^(-1)cm^(-2)for NH_(3)production.Characterization and theoretical calculations revealed that Er-doping facilitated the electronic modulation of CoP in Er-CoP@NC/TM,which regulated the adsorption behaviors of intermediates and was the rate-limiting step for the eNO_(2)-RR,thereby enhancing the electrocatalytic performance.Quenching experiments and electron paramagnetic resonance tests suggest that both direct electrocatalytic reduction by active hydrogen and electron transfer are critical for the eNO_(2)-RR for NH_(3)synthesis.Furthermore,Er-CoP@NC/TM exhibited high performance across a wide range of NO_(2)-concentrations(0.05-0.1 mol L^(-1))and pH values(4-13).In addition,the catalyst demonstrated strong resistance to anions and a long cycle life in simulated wastewater environments.This study offers a powerful approach for the remediation of NO_(2)-wastewater and recovery of valuable inorganic compounds.展开更多
Red mud(RM)is a solid waste generated in the aluminum industry after the extraction of alumina oxide;its multiple elements and higher pH value likely pose a severe threat to the environment after treatment.However,RM&...Red mud(RM)is a solid waste generated in the aluminum industry after the extraction of alumina oxide;its multiple elements and higher pH value likely pose a severe threat to the environment after treatment.However,RM's higher concentrations of metal components,particularly Fe_(2)O_(3)and rare earth elements(REEs),render RM promising for catalytic application.Hence,this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction(NARR).RM calcined at 500℃(RM-500)exhibited excellent catalytic performance.Faradaic efficiency of ammonia(FENH_(3))in an electrolyte solution containing 1 mol·L^(-1)NO_(3)-achieved a maximum value of 92.3%at-0.8 V(vs.RHE).Additionally,24-h cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR.The RM-500 demonstrated a high FE of NH_(3)-to-NO_(3)-of 89.7%at 1.85 V(vs.RHE),showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.展开更多
In this work,an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction(e NO_(3)RR)for synthesis of ammonia(NH_(3))under ambient conditions.The substrate of MnOO...In this work,an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction(e NO_(3)RR)for synthesis of ammonia(NH_(3))under ambient conditions.The substrate of MnOOH plays an important role on the size and electronic structure of Cu nanoparticles,where Cu has the ultrafine size of 2.2 nm and positive shift of its valence states,which in turn causes the increased number of Cu active sites and enhanced intrinsic activity of every active site.As a result,this catalyst realizes an excellent catalytic performance on eNO_(3)RR with the maximal NH_(3)Faraday efficiency(FE)(96.8%)and the highest yield rate(55.51 mg h^(-1)cm^(-2))at a large NH_(3)partial current density of700 m A/cm^(2),which could help to promote the industrialization of NH_(3)production under ambient conditions.展开更多
The efficient and cost-effective implementation of ammonia borane(AB)hydrolysis dehydrogenation for hydrogen storage is crucial.This study investigated the role of solid acid Amberlyst-15(A-15)for hydrogen evolution f...The efficient and cost-effective implementation of ammonia borane(AB)hydrolysis dehydrogenation for hydrogen storage is crucial.This study investigated the role of solid acid Amberlyst-15(A-15)for hydrogen evolution from AB hydrolysis.Notably,AB hydrogen evolution rate can reach 194.15 ml·min^(-1)at 30℃,with a low apparent activation energy of 8.20 kJ·mol^(-1).After five cycles of reuse,the reaction involving A-15 could keep a conversion rate of about 93%.The AB hydrolysis follows quasi first-order kinetics with respect to the AB concentration and quasi zero-order kinetics with respect to the A-15 mass.According to the characterization results of XRD,ATR-FTIR,and in-situ MS,the boric acid was the dominant hydrolyzate,while water as a hydrogen donor in this reaction.Furthermore,based on the reasoning that hydrogen bonds between A-15 and AB(aq)promotes the diffusion of AB,release of H2 and the cleavage of O-H bond of H2O,a possible mechanism was proposed.展开更多
The deployment of non-precious metal catalysts for the production of COx-free hydrogen via the ammonia decomposition reaction(ADR)presents a promising yet great challenge.In the present study,two crystal structures of...The deployment of non-precious metal catalysts for the production of COx-free hydrogen via the ammonia decomposition reaction(ADR)presents a promising yet great challenge.In the present study,two crystal structures of α-MoC and β-Mo_(2)C catalysts with different Mo/C ratios were synthesized,and their ammonia decomposition performance as well as structural evolution in ADR was investigated.The β-Mo_(2)C catalyst,characterized by a higher Mo/C ratio,demonstrated a remarkable turnover frequency of 1.3 s^(-1),which is over tenfold higher than that ofα-MoC(0.1 s^(-1)).An increase in the Mo/C ratio of molybdenum carbide revealed a direct correlation between the surface Mo/C ratio and the hydrogen yield.The transient response surface reaction indicated that the combination of N*and N*derived from NH_(3) dissociation represents the rate-determining step in the ADR,andβ-Mo2C exhibited exceptional proficiency in facilitating this pivotal step.Concurrently,the accumulation of N*species on the carbide surface could induce the phase transition of molybdenum carbide to nitride,which follows a topological transformation.It is discovered that such phase evolution was affected by the Mo-C surface and reaction temperature simultaneously.When the kinetics of combination of N*was accelerated by rising temperatures and its accumulation on the carbide surface was mitigated,β-Mo_(2)C maintained its carbide phase,preventing nitridation during the ADR at 810℃.Our results contribute to an in-depth understanding of the molybdenum carbides’catalytic properties in ADR and highlight the nature of the carbide-nitride phase transition in the reaction.展开更多
Electrochemical reduction of nitrate(NO_(3^(-)))serves as an eco-friendly friendly alternative to the conventional Haber-Bosch ammonia(NH_(3))synthesis process.The Cu electrocatalyst is widely recognized for its stron...Electrochemical reduction of nitrate(NO_(3^(-)))serves as an eco-friendly friendly alternative to the conventional Haber-Bosch ammonia(NH_(3))synthesis process.The Cu electrocatalyst is widely recognized for its strong adsorption capacity towards nitrate,but its limited H adsorption and slow hydrogenation of oxynitride intermediates hinder the efficiency of converting NO_(3^(-))into NH_(3).Herein,a series of nanocomposite catalysts composed of CuO nanostructure with low NiO content that grow in-situ on carbon paper(Cu O/Ni O_(x)-CP)were synthesized via hydrothermal method and calcination for enhanced nitrate electroreduction utilizing the strong nitrate adsorption capacity of copper and excellent water dissociation ability of NiO to supply hydrogen free radicals(·H).In-situ Raman spectroscopy reveals dynamic reconstruction of Cu/NiO_(x)during the electrochemical nitrate reduction process from Cu O/NiO_(x).Due to the synergistic effect of Cu and NiO,a high Faradaic efficiency(FE,~97.9%)and yield rate(YR,391.5μmol h^(-1)cm^(-2))of ammonia are achieved on CuO/NiO_(2.3%)-CP.Electron paramagnetic resonance(EPR)proves that the presence of Ni O enhances the generation of·H,which can be rapidly consumed during nitrate reduction process.Density functional theory(DFT)calculations indicate that the activation energy of Ni O(0.57 eV)is much lower than Cu(0.84 e V)for water splitting to generate·H,thus facilitating*NO hydrogenations.This drives us to create more effective catalysts for nitrate reduction under neutral conditions by promoting H2O dissociation.展开更多
Ammonia is the cornerstone of modern agriculture,providing a critical nitrogen source for global food production and serving as a key raw material for numerous industrial chemicals.Electrocatalytic nitrate reduction,a...Ammonia is the cornerstone of modern agriculture,providing a critical nitrogen source for global food production and serving as a key raw material for numerous industrial chemicals.Electrocatalytic nitrate reduction,as an environmentally friendly method for synthesizing ammonia,not only mitigates the reliance on current ammonia synthesis processes fed by traditional fossil fuels but also effectively reduces nitrate pollution resulting from agricultural and industrial activities.This review explores the fundamental principles of electrocata lytic nitrate reduction,focusing on the key steps of electron transfer and ammonia formation.Additionally,it summarizes the critical factors influencing the performance and selectivity of the reaction,including the properties of the electrolyte,operating voltage,electrode materials,and design of the electrolytic cell.Further discussion of recent advances in electrocatalysts,including pure metal catalysts,metal oxide catalysts,non-metallic catalysts,and composite catalysts,highlights their significant roles in enhancing both the efficiency and selectivity of electrocata lytic nitrate to ammonia(NRA)reactions.Critical challenges for the industrial NRA trials and further outlooks are outlined to propel this strategy toward real-world applications.Overall,the review provides an in-depth overview and comprehensive understanding of electrocata lytic NRA technology,thereby promoting further advancements and innovations in this domain.展开更多
基金Integrating method of absorption and reaeration for CO_(2) capture(2023ZZ0101).
文摘Since the proposal of achieving dual carbon goals,countries worldwide have been actively seeking next-generation energy technologies.Ammonia energy,particularly green ammonia,has recently become a focal point of global attention.The global green ammonia market is expected to grow from USD 17 million in 2021 to USD 5.415 billion by 2030,with a growth rate of 90.2%during this period.As a fossil energy company primarily focused on oil and natural gas,CNPC faces significant pressure to transition to low-carbon operations and achieve dual carbon goals.Keeping track of the current status and technological advancements in ammonia energy development can support CNPC in more effectively implementing its new energy strategy.
基金supported by the National Natural Science Foundation of China(22162004,22479031)the Guangxi Science and Technology Program(2023AB38061)+1 种基金the Innovation Project of Guangxi Graduate Education(YCBZ2024053)the Highperformance Computing Platform of Guangxi University。
文摘The oxophilicity of metal oxides is usually utilized to improve the ammonia oxidation reaction(AOR)activity of Pt-based catalysts.But the effect of strong interaction between Pt and metal oxides on AOR is not studied.Herein,experimental and density functional theory calculation results indicate that a strong interaction is built between Pt and reducible CeOx by high-temperature reduction,which induces the electronic interaction due to the difference of work fu nction,then optimizing the competitive adsorption behavior of*OH and*NH_(3)based on hard-soft acid-base principle.Accordingly,the optimal sample achieves an AOR peak current density of 329 mA mg_(Pt)^(-1),which is 2.4 times that of Pt.Meanwhile,it also shows satisfied hydrogen evolution reaction activity with an overpotential of only 24.3 mV at-10 mA cm^(-2)due to the optimization of*H adsorption energy on Pt by CeO_(x).Therefore,this work proposes an AOR activity enhancement mechanism of metal oxides in terms of the strong interaction,and sheds light on developing effective bifunctional catalysts for ammonia electrolysis.
基金the National Key Research and Development Program of China(No.2022YFB4102000)the National Natural Science Foundation of China(Nos.22102018 and 52171201)+5 种基金the Huzhou Science and Technology Bureau(No.2022GZ45)the China Postdoctoral Science Foundation-Funded Project(No.2022M710601)the Huzhou Science and Technology Bureau(No.2023GZ02)the Natural Science Foundation of Sichuan Province(No.24NSFSC5779)the National Natural Science Foundation of China(Nos.22322201 and 22278067)the Natural Science Foundation of Sichuan Province(No.2023NSFSC0094)。
文摘As an emergent energy carrier,ammonia benefits from a well-established industrial infrastructure for its transportation and production,positioning it as a promising candidate toward a carbon-free energy landscape.Within this context,the electrocatalytic ammonia oxidation reaction(AOR)is pivotal.Platinum(Pt),recognized as the most efficient AOR catalyst,has undergone extensive development over the years,yielding notable advancements across various domains,ranging from elucidating the reaction mechanism to exploring innovative materials.This review begins by elucidating the mechanism of ammonia oxidation,summarizing the evolution of the mechanism and the diverse intermediates identified through various detection methods.Subsequently,it outlines the research progress surrounding different Pt-based catalysts,followed by a discussion on standard protocols for electrochemical ammonia oxidation testing,which facilitates meaningful comparisons across studies and catalyzes the development of more efficient and potent catalysts.Moreover,the review addresses current challenges in ammonia oxidation and outlines potential future directions,providing a comprehensive outlook on the field.
基金supported by the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Development Special Fund of Xiamen(No.23YYST064QCB36)the Natural Science Foundation of Fujian Province(No.2021J011210).
文摘The removal of ammonia nitrogen(NH_(4)^(+)-N)and bacteria from aquaculture wastewater holds paramount ecological and production significance.In this study,Pt/RuO_(2)/g-C_(3)N_(4)photocatalysts were prepared by depositing Pt and RuO_(2)particles onto g-C_(3)N_(4).The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and UV–vis diffuse reflectance spectrometer(UV–vis DRS).The photocatalysts were then applied to the removal of both NH_(4)^(+)-N and bacteria from simulated mariculture wastewater.The results clarified that the removals of both NH_(4)^(+)-N and bacteria were in the sequence of g-C_(3)N_(4)<RuO_(2)/g-C_(3)N_(4)<Pt/g-C_(3)N_(4)<Pt/RuO_(2)/g-C_(3)N_(4).This magnificent photocatalytic ability of Pt/RuO_(2)/g-C_(3)N_(4)can be interpreted by the transfer of holes from g-C_(3)N_(4)to RuO_(2)to facilitate the in situ generation of HClO from Cl^(−)in wastewater,while Pt extracts photogenerated electrons for H_(2)formation to enhance the reaction.The removal of NH_(4)^(+)-N and disinfection effect were more pronounced in simulated seawater than in purewater.The removal efficiency ofNH_(4)^(+)-N increases with an increase in pH of wastewater,while the bactericidal effect was more significant under a lower pH in a pH range of 6–9.In actual seawater aquaculture wastewater,Pt/RuO_(2)/g-C_(3)N_(4)still exhibits effective removal efficiency of NH_(4)^(+)-N and bactericidal performance under sunlight.This study provides an alternative avenue for removement of NH_(4)^(+)-N and bacteria from saline waters under sunlight.
基金supported by the Joint Funds of the National Natural Science Foundation of China(No.U21A2027)the New Cornerstone Science Foundation through the XPLORER PRIZE(2023-1033).
文摘This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to 2020.Utilizing data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and 2020.The spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural activities.NH_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to 2020.The highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to 2020.Agricultural emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban zones.Regions within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)VCDs.The rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem model.The concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)VCDs.This emphasizes the crucial role of environmental policies targeting the reduction of these acidic gases.Effective emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.
基金National Natural Science Foundation of China (52371228, 52402045)fund of Key Laboratory of Advanced Materials of Ministry of Education(Advmat-2414)。
文摘Electrocatalytic nitrate reduction reaction (NO_(3)-RR) to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution issues.We report a CuO nanoparticles incorporated on nitrogen-doped porous carbon (CuO@NC) catalyst for NO_(3)-RR.Part of Cu(Ⅱ) is reduced to Cu(Ⅰ) during the NO_(3)-RR process to construct Cu(Ⅰ)-Cu(Ⅱ) pairs,confirmed by in situ X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.Density functional theory (DFT) calculations indicated that the formation of Cu(Ⅰ) could provide a reaction path with smaller energy barrier for NO_(3)-RR,while Cu(Ⅱ) effectively suppressed the competition of hydrogen evolution reaction (HER).As a result,CuO@NC catalyst achieved a Faradaic efficiency of 84.2% at -0.49 V versus reversible hydrogen electrode (RHE),and a NH_(3)yield rate of 17.2 mg h^(-1)mg^(-1)cat.at -0.79 V vs.RHE,higher than the HaberBosch process (<3.4 g h^(-1)g^(-1)cat.).This work may open a new avenue for effective NO_(3)-RR by modulating oxidation states.
文摘Ultrafine,highly dispersed Pt clusters were immobilized onto the Co nanoparticle surfaces by one-step pyrolysis of the precursor Pt(Ⅱ)-encapsulating Co-MOF-74.Owing to the small size effects of Pt clusters as well as the strongly enhanced synergistic interactions between Pt and Co atoms,the obtained Pt-on-Co/C400 catalysts exhib-ited excellent catalytic activity toward the hydrolysis of ammonia borane with an extremely high turnover frequency(TOF)value of 3022 min^(-1)at 303 K.Durability test indicated that the obtained Pt-on-Co/C400 catalysts possessed high catalytic stability,and there were no changes in the catalyst structures and catalytic activities after 10 cycles.
基金supported by the National Natural Science Foundation of China(21908135)Natural Science Foundation of Shanxi Datong University(2022K23)+1 种基金Graduate Research Innovation and Practice Innovation Projects of Shanxi Datong University(23CX31)Postgraduate Educational Reform and Research Program of Shanxi Datong University(23JG07)。
文摘Ammonia borane(AB)has received much attention as an environmentally friendly,non-toxic,room temperature stable hydrogen storage material with high hydrogen content of 19.6%.However,its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts.In this work,it is found that the prepared Raney Ni W-r treated with high concentration of NaOH(6.25 mol/L)at 110℃exhibited excellent catalytic performance for AB hydrolysis at room temperature.The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials,even higher than that of the 20%Pt/C catalyst.Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency(TOF)value is as high as 51.42 min-1.Owing to its high density and magnetic properties,the catalyst is very easy for magnetic separation.Furthermore,possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed.As a well-established industrial catalyst,Raney Ni has been prepared on a large scale at low cost.This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.
基金supported by Taishan Scholars Foundation of Shandong province(tsqn 201909058)。
文摘In recent years,photocatalytic N_(2) reduction for ammonia synthesis at room temperature and atmospheric pressure has gradually become a research hotspot,exhibiting extremely high development potential.However,the low photogenerated charge separation efficiency and the lack of effective active sites seriously constrain the reaction efficiencies of semiconductor photocatalysts for N_(2) reduction of ammonia synthesis.Therefore,the rational design of catalytic materials is the key to enhance the photocatalytic N_(2) reduction reaction of ammonia synthesis.Transition metal Ru as the active center not only accelerates the adsorption and activation of N_(2) molecules,but also has good selectivity for N_(2) reduction.Moreover,the interaction between the metal and the support can effectively regulate the electronic structure of the active site,accelerate the photogenerated electron transfer,and significantly enhance the photocatalytic activity.Based on this,this review systematically investigates the Ru co-semiconductors to realize efficient photocatalytic N_(2) reduction for ammonia synthesis,and introduces its basic principles.Specifically,the Ru co-semiconductor photocatalytic material systems are introduced,such as TiO2-based,g-C3N4-based,and metal oxide materials,including the design of catalysts,crystal structures,and other characteristics.In addition,the modification strategies of photocatalytic N_(2) reduction ammonia synthesis materials are also presented,including loading/doping,defect engineering,construction of heterojunctions,and crystal surface modulation.Furthermore,the progress and shortcomings of the application of Ru co-semiconductors in these processes are summarized and comprehensively discussed,and the future outlook of Ru co-semiconductors in photocatalytic N_(2) reduction ammonia synthesis applications is proposed.
文摘This work investigates the potential of low-pressure,medium-speed dual-fuel engines for cleaner maritime transportation.The thermodynamic performance of these engines is explored using three alternative fuels:liquefied natural gas(LNG),methanol,and ammonia.A parametric analysis examines the effect of adjustments to key engine parameters(compression ratio,boost pressure,and air-fuel ratio)on performance.Results show an initial improvement in performance with an increase in compression ratio,which reaches a peak and then declines.Similarly,increases in boost pressure and air-fuel ratio lead to linear performance gains.However,insufficient cooling reduces the amount of fuel burned,which hinders performance.Exergy analysis reveals significant exergy destruction within the engine,which ranges from 69.96%(methanol)to 78.48%(LNG).Notably,the combustion process is the leading cause of exergy loss.Among the fuels tested,methanol exhibits the lowest combustion-related exergy destruction(56.41%),followed by ammonia(62.12%)and LNG(73.77%).These findings suggest that methanol is a promising near-term alternative to LNG for marine fuel applications.
基金This work was supported by the High-level Innovative Research Institute from the Department of Science and Technology of Guangdong Province(Grant No.2020B0909010003)the Ministry of Education of China(Grant No.8091B02052401).
文摘To meet the demand for air-breathing power for wide-range vehicles at Mach 0–10,two thermal cycles with ammonia as the fuel and coolant were analyzed,namely the precooled rocket-turbine cycle(PC-RT)and the precooled gas-turbine cycle.Firstly,the operating modes of the precooled cycle engines were divided into turbine mode,precooling mode,and ramjet mode.Secondly,a fluid-structure coupling heat transfer program was used to evaluate the cooling effects of different fuels on the incoming high-temperature air.The result shows that the equivalent heat sink of ammonia is higher than that of other fuels and can meet the cooling requirement of at least Mach 4 in the precooling mode.Thirdly,the performance of the PC-RT in the turbine and precooling modes was compared at Mach 2.5.The result shows that air precooling alleviates the restriction of the pumping pressure on the minimum requiredβand improves the specific thrust within a reasonable range ofβ.Fourthly,the performance of the precooled cycle engines was compared when using different fuels.The result shows that the specific thrust of ammonia is greater than that of other fuels,and the performance advantages of ammonia are the most obvious in the precooling mode due to its highest equivalent heat sink.To sum up,the precooled cycle engines with ammonia as the fuel and coolant presented in this study have the advantages of no carbon emissions,low cost,high specific thrust,and no clogging of the cooling channels by cracking products.They are suitable for applications such as the first-stage power of the two-stage vehicle,and high Mach numbers air-breathing flight.
基金supported by the PhD Research Project of Yan'an University(No.YAU202411439)Shaanxi Province College Students Innovation and Entrepreneurship Training Program(No.S202410719170)Princess Nourah bint Abdulrahman University Researchers Supporting Project(No.PNURSP2025R398)。
文摘The electrochemical nitrogen reduction reaction(eNRR)presents a sustainable alternative to the energy-intensive Haber-Bosch process for ammonia(NH_(3))production.This review examines the fundamental principles of eNRR,emphasizing the critical roles of proton-exchange membranes and electrolytes in facilitating efficient nitrogen(N_(2))reduction.Special attention is given to single-atom catalysts(SACs),highlighting their unique structural and electronic properties that contribute to enhanced catalytic performance.The discussions encompass SACs based on precious metals,non-precious metals,and non-metallic materials,delving into their synthesis methods,coordination environments,and activity in the eNRR.This review also elucidates current challenges in the field and proposes future research directions aimed at optimizing SACs design to enhance eNRR efficiency.
基金supported by the National Key R&D Program of China(2022YFD1200600)the National Natural Science Foundation of China(32002110)the earmarked fund for China Agriculture Research System(CARS-20)。
文摘Blocking the development of edible mushrooms will affect the production cycle and yield of fruiting bodies.Phenylalanine ammonia lyase(PAL,EC 4.3.1.24.)is an enzyme that catalyzes the deamination of phenylalanine to form trans-cinnamic acid.Previous studies have shown that a decrease in pal1 gene transcription delays fruiting body development in Pleurotus ostreatus.Herein,we used wild type(WT)and RNA interference(RNAi)strains to study the molecular regulation of pal1 by RNA sequencing and Agrobacterium-mediated genetic transformation.Our results showed that interference with the pal1 gene resulted in reductions in the total PAL enzyme activity and the total phenol content,as well as an increase in the intracellular H_(2)O_(2)content.RNA-Seq data demonstrated that the significantly enriched KEGG terms were mainly related to the peroxisome pathway,MAPK signaling pathway-yeast and three other pathways,and the catalase(CAT)gene cat1 is also involved in multiple pathways that were enriched above.Exogenous H_(2)O_(2)significantly enhanced the transcription of the cat1 gene and elevated total CAT enzymatic activity.Moreover,the levels of cat1 gene transcription and the total CAT enzymatic activity in the RNAi-pal1 strains gradually become closer to those in the WT strain through the removal of H_(2)O_(2),which indicated that pal1 regulated the expression of cat1 by affecting the intracellular H_(2)O_(2)content.Finally,the overexpression of the cat1 gene in P.ostreatus caused growth retardation,especially during the process of primordia formation.In conclusion,this study demonstrated that PAL1 affects cat1 gene expression through the signaling molecule H_(2)O_(2)and regulates the development of P.ostreatus.The findings of this study enhance our understanding of the molecular developmental mechanism of edible mushrooms.
文摘The electrochemical conversion of toxic nitrite(NO_(2)-)is a promising approach for the simultaneous removal of nitrogen contaminants and synthesis of ammonia(NH_(3)).In this study,we present the Er-doping-induced electronic modulation of CoP integrated with nitrogen-doped carbon(CN)nanosheets supported on a titanium mesh(Er-CoP@NC/TM)for the electrocatalytic NO_(2)-reduction reaction(eNO_(2)-RR)for NH_(3)synthesis.The catalyst demonstrates a high Faraday efficiency of 97.08±2.22%and a high yield of 2087.60±17.10μmol h^(-1)cm^(-2)for NH_(3)production.Characterization and theoretical calculations revealed that Er-doping facilitated the electronic modulation of CoP in Er-CoP@NC/TM,which regulated the adsorption behaviors of intermediates and was the rate-limiting step for the eNO_(2)-RR,thereby enhancing the electrocatalytic performance.Quenching experiments and electron paramagnetic resonance tests suggest that both direct electrocatalytic reduction by active hydrogen and electron transfer are critical for the eNO_(2)-RR for NH_(3)synthesis.Furthermore,Er-CoP@NC/TM exhibited high performance across a wide range of NO_(2)-concentrations(0.05-0.1 mol L^(-1))and pH values(4-13).In addition,the catalyst demonstrated strong resistance to anions and a long cycle life in simulated wastewater environments.This study offers a powerful approach for the remediation of NO_(2)-wastewater and recovery of valuable inorganic compounds.
基金supported by grants from the National Natural Science Foundation of China (22178339)2023 Innovation-driven Development Special Foundation of Guangxi(AA23023021)the Hundred Talents Program (A) of the Chinese Academy of Sciences
文摘Red mud(RM)is a solid waste generated in the aluminum industry after the extraction of alumina oxide;its multiple elements and higher pH value likely pose a severe threat to the environment after treatment.However,RM's higher concentrations of metal components,particularly Fe_(2)O_(3)and rare earth elements(REEs),render RM promising for catalytic application.Hence,this work showed an efficient high-speed RM to catalyze electrocatalytic nitrate-to-ammonia reduction reaction(NARR).RM calcined at 500℃(RM-500)exhibited excellent catalytic performance.Faradaic efficiency of ammonia(FENH_(3))in an electrolyte solution containing 1 mol·L^(-1)NO_(3)-achieved a maximum value of 92.3%at-0.8 V(vs.RHE).Additionally,24-h cycle testing and post-reaction PXRD and SEM indicated that the RM-500 electrocatalyst is stable during NARR.The RM-500 demonstrated a high FE of NH_(3)-to-NO_(3)-of 89.7%at 1.85 V(vs.RHE),showing great potential in the ammonia fuel cells technology and achieving the nitrogen cycle.
基金supported in part by National Natural Science Foundation of China(No.51925102)National Key R&D Program of China(No.2022YFA1504101)。
文摘In this work,an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction(e NO_(3)RR)for synthesis of ammonia(NH_(3))under ambient conditions.The substrate of MnOOH plays an important role on the size and electronic structure of Cu nanoparticles,where Cu has the ultrafine size of 2.2 nm and positive shift of its valence states,which in turn causes the increased number of Cu active sites and enhanced intrinsic activity of every active site.As a result,this catalyst realizes an excellent catalytic performance on eNO_(3)RR with the maximal NH_(3)Faraday efficiency(FE)(96.8%)and the highest yield rate(55.51 mg h^(-1)cm^(-2))at a large NH_(3)partial current density of700 m A/cm^(2),which could help to promote the industrialization of NH_(3)production under ambient conditions.
基金support from the National Natural Science Foundation of China(22222808,21978200,22208330)the Postdoctoral Fellowship Programof CPSF(GZC20241204)+1 种基金the China Postdoctoral Science Foundation-Tianjin Joint Support Program(2023T022TJ)the Haihe Laboratory of Sustainable Chemical Transformations for financial support.
文摘The efficient and cost-effective implementation of ammonia borane(AB)hydrolysis dehydrogenation for hydrogen storage is crucial.This study investigated the role of solid acid Amberlyst-15(A-15)for hydrogen evolution from AB hydrolysis.Notably,AB hydrogen evolution rate can reach 194.15 ml·min^(-1)at 30℃,with a low apparent activation energy of 8.20 kJ·mol^(-1).After five cycles of reuse,the reaction involving A-15 could keep a conversion rate of about 93%.The AB hydrolysis follows quasi first-order kinetics with respect to the AB concentration and quasi zero-order kinetics with respect to the A-15 mass.According to the characterization results of XRD,ATR-FTIR,and in-situ MS,the boric acid was the dominant hydrolyzate,while water as a hydrogen donor in this reaction.Furthermore,based on the reasoning that hydrogen bonds between A-15 and AB(aq)promotes the diffusion of AB,release of H2 and the cleavage of O-H bond of H2O,a possible mechanism was proposed.
文摘The deployment of non-precious metal catalysts for the production of COx-free hydrogen via the ammonia decomposition reaction(ADR)presents a promising yet great challenge.In the present study,two crystal structures of α-MoC and β-Mo_(2)C catalysts with different Mo/C ratios were synthesized,and their ammonia decomposition performance as well as structural evolution in ADR was investigated.The β-Mo_(2)C catalyst,characterized by a higher Mo/C ratio,demonstrated a remarkable turnover frequency of 1.3 s^(-1),which is over tenfold higher than that ofα-MoC(0.1 s^(-1)).An increase in the Mo/C ratio of molybdenum carbide revealed a direct correlation between the surface Mo/C ratio and the hydrogen yield.The transient response surface reaction indicated that the combination of N*and N*derived from NH_(3) dissociation represents the rate-determining step in the ADR,andβ-Mo2C exhibited exceptional proficiency in facilitating this pivotal step.Concurrently,the accumulation of N*species on the carbide surface could induce the phase transition of molybdenum carbide to nitride,which follows a topological transformation.It is discovered that such phase evolution was affected by the Mo-C surface and reaction temperature simultaneously.When the kinetics of combination of N*was accelerated by rising temperatures and its accumulation on the carbide surface was mitigated,β-Mo_(2)C maintained its carbide phase,preventing nitridation during the ADR at 810℃.Our results contribute to an in-depth understanding of the molybdenum carbides’catalytic properties in ADR and highlight the nature of the carbide-nitride phase transition in the reaction.
基金supported by the National Natural Science Foundation of China(No.U22A20253)。
文摘Electrochemical reduction of nitrate(NO_(3^(-)))serves as an eco-friendly friendly alternative to the conventional Haber-Bosch ammonia(NH_(3))synthesis process.The Cu electrocatalyst is widely recognized for its strong adsorption capacity towards nitrate,but its limited H adsorption and slow hydrogenation of oxynitride intermediates hinder the efficiency of converting NO_(3^(-))into NH_(3).Herein,a series of nanocomposite catalysts composed of CuO nanostructure with low NiO content that grow in-situ on carbon paper(Cu O/Ni O_(x)-CP)were synthesized via hydrothermal method and calcination for enhanced nitrate electroreduction utilizing the strong nitrate adsorption capacity of copper and excellent water dissociation ability of NiO to supply hydrogen free radicals(·H).In-situ Raman spectroscopy reveals dynamic reconstruction of Cu/NiO_(x)during the electrochemical nitrate reduction process from Cu O/NiO_(x).Due to the synergistic effect of Cu and NiO,a high Faradaic efficiency(FE,~97.9%)and yield rate(YR,391.5μmol h^(-1)cm^(-2))of ammonia are achieved on CuO/NiO_(2.3%)-CP.Electron paramagnetic resonance(EPR)proves that the presence of Ni O enhances the generation of·H,which can be rapidly consumed during nitrate reduction process.Density functional theory(DFT)calculations indicate that the activation energy of Ni O(0.57 eV)is much lower than Cu(0.84 e V)for water splitting to generate·H,thus facilitating*NO hydrogenations.This drives us to create more effective catalysts for nitrate reduction under neutral conditions by promoting H2O dissociation.
基金supported by the National Key Research and Development Program of China(2023YFE0120900)the National Natural Science Foundation of China(52377160)+2 种基金the National Natural Science Foundation of China National Young Talents Project(GYKP010)Shaanxi Provincial Natural Science Program(2023-JCYB-425)Xi’an Jiaotong University Young Top Talents Program。
文摘Ammonia is the cornerstone of modern agriculture,providing a critical nitrogen source for global food production and serving as a key raw material for numerous industrial chemicals.Electrocatalytic nitrate reduction,as an environmentally friendly method for synthesizing ammonia,not only mitigates the reliance on current ammonia synthesis processes fed by traditional fossil fuels but also effectively reduces nitrate pollution resulting from agricultural and industrial activities.This review explores the fundamental principles of electrocata lytic nitrate reduction,focusing on the key steps of electron transfer and ammonia formation.Additionally,it summarizes the critical factors influencing the performance and selectivity of the reaction,including the properties of the electrolyte,operating voltage,electrode materials,and design of the electrolytic cell.Further discussion of recent advances in electrocatalysts,including pure metal catalysts,metal oxide catalysts,non-metallic catalysts,and composite catalysts,highlights their significant roles in enhancing both the efficiency and selectivity of electrocata lytic nitrate to ammonia(NRA)reactions.Critical challenges for the industrial NRA trials and further outlooks are outlined to propel this strategy toward real-world applications.Overall,the review provides an in-depth overview and comprehensive understanding of electrocata lytic NRA technology,thereby promoting further advancements and innovations in this domain.
