A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isotherm...A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isothermal experiments. As a result of the competitive diffusion of alloying elements, the oxide scale included an outermost porous oxide layer (OOL), an inner relatively dense oxide layer (IOL), and an internal oxide zone (IOZ), depending on the temperature and time. A high temperature led to the formation of large voids at the IOL/IOZ interface. At 1200℃, the continuity of the Cr-rich oxide layer in the IOL was destroyed, and thus, spallation occurred. Extension of oxidation time contributed to the size of Al-rich oxide particles with the increase in the IOZ. Based on this finding,the oxidation kinetics of GH4738 was discussed, and the corresponding oxidation behavior at 900-1100℃ was predicted.展开更多
In order to better understand the specific substituent effects on the electrochemical oxidation process of β-O-4 bond, a series of methoxyphenyl type β-O-4 dimer model compounds with different localized methoxyl gro...In order to better understand the specific substituent effects on the electrochemical oxidation process of β-O-4 bond, a series of methoxyphenyl type β-O-4 dimer model compounds with different localized methoxyl groups, including 2-(2-methoxyphenoxy)-1-phenylethanone, 2-(2-methoxyphenoxy)-1-phenylethanol, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanol, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanol have been selected and their electrochemical properties have been studied experimentally by cyclic voltammetry, and FT-IR spectroelectrochemistry. Combining with electrolysis products distribution analysis and density functional theory calculations, oxidation mechanisms of all six model dimers have been explored. In particular, a total effect from substituents of both para-methoxy(on the aryl ring closing to Cα) and Cα-OH on the oxidation mechanisms has been clearly observed, showing a significant selectivity on the Cα-Cβbond cleavage induced by electrochemical oxidations.展开更多
The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to ...The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance,but at the cost of mass activity due to the coverage of modifiers on Pt surface.Herein,we constructed dual junctions'Pt/nitrogen-doped carbon(Pt/NC)andδ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles,simultaneously endowing it with high mass activity and durability of alkaline HOR.Moreover,the unique structure of Pt-MoC@NC endows Pt with a high COtolerance at 1,000 ppm CO/H_(2),a quality that commercial Pt-C catalyst lacks.The theoretical calculations not only confirm the diffusion of electrons from Pt/NC to Mo C/NC could occur,but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of*H,*OH and CO.展开更多
Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electr...Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.展开更多
Co-Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue resistance.Therefore,these alloys show potential as crucial high-temperature s...Co-Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue resistance.Therefore,these alloys show potential as crucial high-temperature structural materials for aeroengine and gas turbine hot-end components.Our previous work elucidated the influence of Ti and Ta on the high-temperature mechanical properties of alloys.However,the intricate interaction among elements considerably affects the oxidation resistance of alloys.In this paper,Co-35Ni-10Al-2W-5Cr-2Mo-1Nb-xTi-(5−x)Ta alloys(x=1,2,3,4)with varying Ti and Ta contents were designed and compounded,and their oxidation resistance was investigated at the temperature range from 800 to 1000℃.After oxidation at three test conditions,namely,800℃for 200 h,900℃for 200 h,and 1000℃for 50 h,the main structure of the oxide layer of the alloy consisted of spinel,Cr_(2)O_(3),and Al_(2)O_(3)from outside to inside.Oxides consisting of Ta,W,and Mo formed below the Cr_(2)O_(3)layer.The interaction of Ti and Ta imparted the highest oxidation resistance to 3Ti2Ta alloy.Conversely,an excessive amount of Ti or Ta resulted in an adverse effect on the oxidation resistance of the alloys.This study reports the volatilization of W and Mo oxides during the oxidation process of Co-Ni-based cast superalloys with a high Al content for the first time and explains the formation mechanism of holes in the oxide layer.The results provide a basis for gaining insights into the effects of the interaction of alloying elements on the oxidation resistance of the alloys they form.展开更多
Currently,there is a lack of effective medicines capable of halting or reve rsing the progression of neurodegenerative disorde rs,including amyotrophic lateral sclerosis,Parkinson s disease,multiple sclerosis,or Alzhe...Currently,there is a lack of effective medicines capable of halting or reve rsing the progression of neurodegenerative disorde rs,including amyotrophic lateral sclerosis,Parkinson s disease,multiple sclerosis,or Alzheimer s disease.Given the unmet medical need,it is necessary to reevaluate the existing para digms of how to to rget these diseases.When considering neurodegenerative diseases from a systemic neurometabolic perspective,it becomes possible to explain the shared pathological features.This innovative approach presented in this paper draws upon exte nsive research conducted by the authors and researchers worldwide.In this review,we highlight the importance of metabolic mitochondrial dysfunction in the context of neurodegenerative diseases.We provide an overview of the risk factors associated with developing neurodegenerative disorders,including genetic,epigenetic,and environmental fa ctors.Additionally,we examine pathological mechanisms implicated in these diseases such as oxidative stress,accumulation of misfolded proteins,inflammation,demyelination,death of neurons,insulin resistance,dysbiosis,and neurotransmitter disturbances.Finally,we outline a proposal for the restoration of mitochondrial metabolism,a crucial aspect that may hold the key to facilitating curative therapeutic interventions for neurodegenerative disorders in forthcoming advancements.展开更多
Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability cau...Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry.Herein,we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation.During the seawater oxidation process,CeO_(2)is generated,effectively repelling Cl^(-)and inhibiting the formation of Cl O-,resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater.The prepared Ce-Ni Fe LDH/NF requires only overpotential of 390 m V to achieve the current density of 1 A cm^(-2),while maintaining long-term stability for 500 h,outperforming the performance of Ni Fe LDH/NF(430 m V,150 h)by a significant margin.This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on Ni Fe LDH in seawater electrolysis for oxygen evolution.展开更多
Vegetable oils are a source of energy, essential fatty acids, antioxidants and fat-soluble vitamins useful for human health care and development. These oils also contribute to organoleptic quality of their products’ ...Vegetable oils are a source of energy, essential fatty acids, antioxidants and fat-soluble vitamins useful for human health care and development. These oils also contribute to organoleptic quality of their products’ derivatives. However, their chemical and physical properties can be modified by the mode of their extraction, storage and distribution. These modifications might negatively affect the nutritional quality of the oils. The goals of this study were to: sample different vegetable oils for cosmetic or dietary use marketed in Cameroon, and verify purity and oxidation states of each kind of oil through determination of its acidity, iodine, peroxide, saponification, refractive indexes and the conformity of the labeling. The carotene content, the level of polar components and specific absorbance were also determined. As the result, six oils namely palm, palm kernel, coconut, black cumin, peanut and shea butter were collected. Apart from labeling, chemicals and physicals parameters analyzed were generally in accordance with the Cameroonian and Codex Alimentarius standard. This study suggests that vegetable oils sampled in the Cameroonian market may not expose consumers to lipid oxidation products generating pathological oxidative stress and inflammation. However, efforts in application of existing standard need to be done as far as labeling are concerned.展开更多
The trade-off between efficiency and stability has limited the application of TiO_(2)as a catalyst due to its poor surface reactivity.Here,we present a modification of a TiO_(2)layer with highly stable Sub-5 nm Fe_(2)...The trade-off between efficiency and stability has limited the application of TiO_(2)as a catalyst due to its poor surface reactivity.Here,we present a modification of a TiO_(2)layer with highly stable Sub-5 nm Fe_(2)O_(3)nanoparticles(NP)by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation approach.In situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe_(2)O_(3)NP embedded within porous TiO_(2)layer.Comprehensive surface characterizations with density functional theory demonstrated an improved electronic transition in TiO_(2)due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe;it also unexpectedly increased the active site in the TiO_(2)layer due to uncoordinated electrons in Sub-5 nm Fe_(2)O_(3)NP/TiO_(2)catalyst,thereby enhancing the adsorption of chemical functional groups on the catalyst.This unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol,achieving approximately 99%efficiency in 20 min without stability decay after 20 consecutive cycles,outperforming previously reported TiO_(2)-based catalysts.This finding proposes a modified-electrochemical strategy enabling facile construction of TiO_(2)with nanoscale oxides extandable to other metal oxide systems.展开更多
Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile me...Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile memories,neuromorphic computation and data encryption.However,the deposition of memristive films often requires expensive equipment,strict vacuum conditions,high energy consumption,and extended processing times.In contrast,electrochemical anodizing can produce metal oxide films quickly(e.g.10 s) under ambient conditions.By means of the anodizing technique,oxide films,oxide nanotubes,nanowires and nanodots can be fabricated to prepare memristors.Oxide film thickness,nanostructures,defect concentrations,etc,can be varied to regulate device performances by adjusting oxidation parameters such as voltage,current and time.Thus memristors fabricated by the anodic oxidation technique can achieve high device consistency,low variation,and ultrahigh yield rate.This article provides a comprehensive review of the research progress in the field of anodic oxidation assisted fabrication of memristors.Firstly,the principle of anodic oxidation is introduced;then,different types of memristors produced by anodic oxidation and their applications are presented;finally,features and challenges of anodic oxidation for memristor production are elaborated.展开更多
The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain method...The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain methods.The phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and EDS.Results show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this temperature.As the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 h.Then,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 h.This internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture sublayer.Also two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 h.This internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)sublayer.Finally,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.展开更多
Electrocatalytic glucose oxidation reaction(GOR)has attracted much attention owing to its crucial role in biofuel cell fabrication.Herein,we load MoO_(3)nanoparticles on carbon nanotubes(CNTs)and use a discharge proce...Electrocatalytic glucose oxidation reaction(GOR)has attracted much attention owing to its crucial role in biofuel cell fabrication.Herein,we load MoO_(3)nanoparticles on carbon nanotubes(CNTs)and use a discharge process to prepare a noblemetal-free MC-60 catalyst containing MoO_(3),Mo_(2)C,and a Mo_(2)C–MoO_(3)interface.In the GOR,MC-60 shows activity as high as 745μA/(mmol/L cm^(2)),considerably higher than those of the Pt/CNT(270μA/(mmol/L cm^(2)))and Au/CNT catalysts(110μA/(mmol/L cm^(2))).In the GOR,the response minimum on MC-60 is as low as 8μmol/L,with a steady-state response time of only 3 s.Moreover,MC-60 has superior stability and anti-interference ability to impurities in the GOR.The better performance of MC-60 in the GOR is attributed to the abundant Mo sites bonding to C and O atoms at the MoO_(3)–Mo_(2)C interface.These Mo sites create active sites for promoting glucose adsorption and oxidation,enhancing MC-60 performance in the GOR.Thus,these results help to fabricate more effi cient noble-metal-free catalysts for the fabrication of glucose-based biofuel cells.展开更多
The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys.In this study,FGH96 alloy powders with various oxygen contents were investigated using high-reso...The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys.In this study,FGH96 alloy powders with various oxygen contents were investigated using high-resolution transmission electron microscopy and atomic probe technology to elucidate the structure evolution of the oxide film.Energy dispersive spectrometer analysis revealed the presence of two distinct components in the oxide film of the alloy powders:amorphous oxide layer covering the γ matrix and amorphous oxide particles above the carbide.The alloying elements within the oxide layer showed a laminated distribution,with Ni,Co,Cr,and Al/Ti,which was attributed to the decreasing oxygen equilibrium pressure as oxygen diffused from the surface into the γ matrix.On the other hand,Ti enrichment was observed in the oxide particles caused by the oxidation and decomposition of the carbide phase.Comparative analysis of the oxide film with oxygen contents of 140,280,and 340 ppm showed similar element distributions,while the thickness of the oxide film varies approximately at 9,14,and 30 nm,respectively.These findings provide valuable insights into the structural analysis of the oxide film on FGH96 alloy powders.展开更多
The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were coll...The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were collected by a thermophoretic system and a quartz filter.The oxidation reactivity,oxidation behaviors,and physicochemical properties of the PM samples were analyzed using thermogravimetric analysis(TGA),high-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectrometry(FTIR),and Raman spectroscopy.The results showed that there was a great difference in the oxidation reactivity of soot particles emitted by the two different diesel engines.A qualitative analysis of the factors influencing oxidation reactivity showed that the nanostructure,degree of graphitization,and relative concentration of aliphatic C—H functional groups were the most important factors,whereas no significant correlation was found between the primary particle size and activation energy of the diesel soot.Based on the oxidation behavior analysis,the diesel soot particles exhibited both internal and surface oxidation modes during the oxidation process.Surface oxidation was dominant during the initial stage,and as oxidation progressed,the mode gradually changed to internal oxidation.Internal oxidation mode of soot particles from the 1K engine was significantly higher than that of CY4102.展开更多
Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile...Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2))is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2)from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2)did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2)catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2)generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.展开更多
This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))wer...This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/Na2SiO3electrolyte.The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic polarization.It was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and dispersed.The nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in grains.It effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge pores.The MAO coating on Zr-FSP sample had good wettability and corrosion resistance.However,TiO_(2)particles were hardly detected in the coating on TiFSP sample.展开更多
Chromia-forming alloys have good resistance to oxidizing agents such as O2, CO2, … It is accepted that the protection of these alloys is always due to the chromia layer formed at the surface of the alloys, which acts...Chromia-forming alloys have good resistance to oxidizing agents such as O2, CO2, … It is accepted that the protection of these alloys is always due to the chromia layer formed at the surface of the alloys, which acts as a barrier between the oxidizing gases and the alloy substrates, forming a diffusion zone that limits the overall reaction rate and leads to parabolic kinetics. But this was not verified in the study devoted to Inconel®625 the oxidation in CO2 that was followed by TGA, with characterizations by XRD, EDS and FIB microscopy. Contrary to what was expected and accepted in similar studies on other chromia-forming alloys, it was shown that the diffusion step that governs the overall reaction rate is not located inside the chromia layer but inside the alloy, precisely inside a zone just beneath the interface alloy/chromia, this zone being depleted in chromium. The chromia layer, therefore, plays no kinetic role and does not directly protect the underlying alloy. This result was demonstrated using a simple test that consisted in removing the chromia layer from the surface of samples partially oxidized and then to continue the thermal treatment: insofar as the kinetics continued without any change in rate, this proved that this surface layer of oxide did not protect the substrate. Based on previous work on many chromia-forming alloys, the possibility of a similar reaction mechanism is discussed. If the chromia layer is not the source of protection for a number of chromia-forming alloys, as is suspected, this might have major consequences in terms of industrial applications.展开更多
A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared,and the evaluation of its high-temperature microstructural stability,oxidation resistance,and mechanical proper...A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared,and the evaluation of its high-temperature microstructural stability,oxidation resistance,and mechanical properties was conducted mainly using its cast polycrystalline alloy.The results disclosed that the morphology of theγ′phase remained stable,and the coarsening rate was slow during the long-term aging at 900–1000℃.The activation energy forγ′precipitate coarsening of alloy 9CoNi-Cr was(402±51)kJ/mol,which is higher compared with those of CMSX-4 and some other Ni-based and Co-based superalloys.Importantly,there was no indica-tion of the formation of topologically close-packed phases during this process.All these factors demonstrated the superior microstructural stability of the alloy.The mass gain of alloy 9CoNi-Cr was 0.6 mg/cm^(2) after oxidation at 1000℃ for 100 h,and the oxidation resistance was comparable to advanced Ni-based superalloys CMSX-4,which can be attributed to the formation of a continuous Al_(2)O_(3) protective layer.Moreover,the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950℃ is comparable to that of the conventional Ni-based cast superalloy,demonstrating the alloy’s good mechanical properties at high temperature.This is partially because high Cr is bene-ficial in improving theγandγ′phase strengths of alloy 9CoNi-Cr.展开更多
A few-layered hexagonal boron nitride nanosheets stabilized platinum nanoparticles(Pt/h-BNNS)is engineered for oxidation-promoted adsorptive desulfurization(OPADS)of fuel oil.It was found that the few-layered structur...A few-layered hexagonal boron nitride nanosheets stabilized platinum nanoparticles(Pt/h-BNNS)is engineered for oxidation-promoted adsorptive desulfurization(OPADS)of fuel oil.It was found that the few-layered structure and the defective sites of h-BNNS not only are beneficial to the stabilization of Pt NPs but also favor the adsorption of aromatic sulfides.By employing Pt/h-BNNS with a Pt loading amount of 1.19 wt%as the active adsorbent and air as an oxidant,a 98.0%sulfur removal over dibenzothiophene(DBT)is achieved along with a total conversion of the DBT to the corresponding sulfones(DBTO_(2)).Detailed experiments show that the excellent desulfurization activity originates from the few-layered structure of h-BNNS and the high catalytic activity of Pt NPs.In addition,the OPADS system with Pt/h-BNNS as the active adsorbent shows remarkable stability in desulfurization performance with the existence of different interferents such as olefin,and aromatic hydrocarbons.Besides,the Pt/h-BNNS can be recycled 12 times without a significant decrease in desulfurization performance.Also,a process flow diagram is proposed for deep desulfurization of fuel oil and recovery of high value-added products,which would promote the industrial application of such OPADS strategy.展开更多
基金financially supported by the National Key R&D Program of China (No.2021YFB3700400)the National Natural Science Foundation of China (Nos.52074030,51904021,and 52174294)。
文摘A high thrust-to-weight ratio poses challenges to the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperatures has been investigated by isothermal and non-isothermal experiments. As a result of the competitive diffusion of alloying elements, the oxide scale included an outermost porous oxide layer (OOL), an inner relatively dense oxide layer (IOL), and an internal oxide zone (IOZ), depending on the temperature and time. A high temperature led to the formation of large voids at the IOL/IOZ interface. At 1200℃, the continuity of the Cr-rich oxide layer in the IOL was destroyed, and thus, spallation occurred. Extension of oxidation time contributed to the size of Al-rich oxide particles with the increase in the IOZ. Based on this finding,the oxidation kinetics of GH4738 was discussed, and the corresponding oxidation behavior at 900-1100℃ was predicted.
基金The authors gratefully acknowledge the financial support of the Natural Science Foundation of China,China(Grant No.21975082 and 21736003)the Guangdong Basic and Applied Basic Research Foundation(Grant Number:2019A1515011472 and 2022A1515011341)the Science and Technology Program of Guangzhou(Grant Number:202102080479).
文摘In order to better understand the specific substituent effects on the electrochemical oxidation process of β-O-4 bond, a series of methoxyphenyl type β-O-4 dimer model compounds with different localized methoxyl groups, including 2-(2-methoxyphenoxy)-1-phenylethanone, 2-(2-methoxyphenoxy)-1-phenylethanol, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2-methoxyphenoxy)-1-(4-methoxyphenyl)ethanol, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanone, 2-(2,6-dimethoxyphenoxy)-1-(4-methoxyphenyl)ethanol have been selected and their electrochemical properties have been studied experimentally by cyclic voltammetry, and FT-IR spectroelectrochemistry. Combining with electrolysis products distribution analysis and density functional theory calculations, oxidation mechanisms of all six model dimers have been explored. In particular, a total effect from substituents of both para-methoxy(on the aryl ring closing to Cα) and Cα-OH on the oxidation mechanisms has been clearly observed, showing a significant selectivity on the Cα-Cβbond cleavage induced by electrochemical oxidations.
基金supported by the National Natural Science Foundation of China (Grant Nos.52072272,52171145 and 22109120)the Zhejiang Provincial Natural Science Foundation of China (LQ21B030002)+1 种基金the Zhejiang Provincial Special Support Program for High-level Talents (2019R52042)the Key programs for Science and Technology Innovation of Wenzhou (ZG2022037)。
文摘The scarcity,high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction(HOR).Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance,but at the cost of mass activity due to the coverage of modifiers on Pt surface.Herein,we constructed dual junctions'Pt/nitrogen-doped carbon(Pt/NC)andδ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles,simultaneously endowing it with high mass activity and durability of alkaline HOR.Moreover,the unique structure of Pt-MoC@NC endows Pt with a high COtolerance at 1,000 ppm CO/H_(2),a quality that commercial Pt-C catalyst lacks.The theoretical calculations not only confirm the diffusion of electrons from Pt/NC to Mo C/NC could occur,but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of*H,*OH and CO.
基金supported by the National Natural Science Foundation of China(21872040,22162004)the Excellent Scholars and Innovation Team of Guangxi Universities,the Innovation Project of Guangxi Graduate Education(YCBZ2022038)the High-performance Computing Platform of Guangxi University.
文摘Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water electrolysis.Herein,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea oxidation.Due to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic activity.Besides,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial practicability.This work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.
基金the National Major Science and Technology Projects of China(Nos.J2019-VII-0010-0150 and J2019-VI-0009-0123)National Natural Science Foundation of China(Nos.52022011 and 52090041)+3 种基金Beijing Nova Program(No.Z211100002121170)Science Center for Gas Turbine Project(No.P2021-A-IV-001-002)Science and Technology on Advanced High Temperature Structural Materials Laboratory(No.6142903210306)Xiaomi Young Scholars Program.
文摘Co-Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue resistance.Therefore,these alloys show potential as crucial high-temperature structural materials for aeroengine and gas turbine hot-end components.Our previous work elucidated the influence of Ti and Ta on the high-temperature mechanical properties of alloys.However,the intricate interaction among elements considerably affects the oxidation resistance of alloys.In this paper,Co-35Ni-10Al-2W-5Cr-2Mo-1Nb-xTi-(5−x)Ta alloys(x=1,2,3,4)with varying Ti and Ta contents were designed and compounded,and their oxidation resistance was investigated at the temperature range from 800 to 1000℃.After oxidation at three test conditions,namely,800℃for 200 h,900℃for 200 h,and 1000℃for 50 h,the main structure of the oxide layer of the alloy consisted of spinel,Cr_(2)O_(3),and Al_(2)O_(3)from outside to inside.Oxides consisting of Ta,W,and Mo formed below the Cr_(2)O_(3)layer.The interaction of Ti and Ta imparted the highest oxidation resistance to 3Ti2Ta alloy.Conversely,an excessive amount of Ti or Ta resulted in an adverse effect on the oxidation resistance of the alloys.This study reports the volatilization of W and Mo oxides during the oxidation process of Co-Ni-based cast superalloys with a high Al content for the first time and explains the formation mechanism of holes in the oxide layer.The results provide a basis for gaining insights into the effects of the interaction of alloying elements on the oxidation resistance of the alloys they form.
文摘Currently,there is a lack of effective medicines capable of halting or reve rsing the progression of neurodegenerative disorde rs,including amyotrophic lateral sclerosis,Parkinson s disease,multiple sclerosis,or Alzheimer s disease.Given the unmet medical need,it is necessary to reevaluate the existing para digms of how to to rget these diseases.When considering neurodegenerative diseases from a systemic neurometabolic perspective,it becomes possible to explain the shared pathological features.This innovative approach presented in this paper draws upon exte nsive research conducted by the authors and researchers worldwide.In this review,we highlight the importance of metabolic mitochondrial dysfunction in the context of neurodegenerative diseases.We provide an overview of the risk factors associated with developing neurodegenerative disorders,including genetic,epigenetic,and environmental fa ctors.Additionally,we examine pathological mechanisms implicated in these diseases such as oxidative stress,accumulation of misfolded proteins,inflammation,demyelination,death of neurons,insulin resistance,dysbiosis,and neurotransmitter disturbances.Finally,we outline a proposal for the restoration of mitochondrial metabolism,a crucial aspect that may hold the key to facilitating curative therapeutic interventions for neurodegenerative disorders in forthcoming advancements.
基金support from the Free Exploration Project of Frontier Technology for Laoshan Laboratory(No.16-02)the National Natural Science Foundation of China(Nos.22072015 and 21927811)。
文摘Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry.Herein,we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation.During the seawater oxidation process,CeO_(2)is generated,effectively repelling Cl^(-)and inhibiting the formation of Cl O-,resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater.The prepared Ce-Ni Fe LDH/NF requires only overpotential of 390 m V to achieve the current density of 1 A cm^(-2),while maintaining long-term stability for 500 h,outperforming the performance of Ni Fe LDH/NF(430 m V,150 h)by a significant margin.This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on Ni Fe LDH in seawater electrolysis for oxygen evolution.
文摘Vegetable oils are a source of energy, essential fatty acids, antioxidants and fat-soluble vitamins useful for human health care and development. These oils also contribute to organoleptic quality of their products’ derivatives. However, their chemical and physical properties can be modified by the mode of their extraction, storage and distribution. These modifications might negatively affect the nutritional quality of the oils. The goals of this study were to: sample different vegetable oils for cosmetic or dietary use marketed in Cameroon, and verify purity and oxidation states of each kind of oil through determination of its acidity, iodine, peroxide, saponification, refractive indexes and the conformity of the labeling. The carotene content, the level of polar components and specific absorbance were also determined. As the result, six oils namely palm, palm kernel, coconut, black cumin, peanut and shea butter were collected. Apart from labeling, chemicals and physicals parameters analyzed were generally in accordance with the Cameroonian and Codex Alimentarius standard. This study suggests that vegetable oils sampled in the Cameroonian market may not expose consumers to lipid oxidation products generating pathological oxidative stress and inflammation. However, efforts in application of existing standard need to be done as far as labeling are concerned.
基金supported by the National Projects of the National Research Foundation(NRF)funded by Republic of Korea(#2022R1F1A1072739 and#2022R1A2C1004392)Prof.Nashrah is also grateful for financial supports by the YU Infra-Project in conjunction with BK21 FOUR National Program(#222A251009)by the Nano-Fab-NRF grant funded by Republic of Korea(#2009-0082580).
文摘The trade-off between efficiency and stability has limited the application of TiO_(2)as a catalyst due to its poor surface reactivity.Here,we present a modification of a TiO_(2)layer with highly stable Sub-5 nm Fe_(2)O_(3)nanoparticles(NP)by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation approach.In situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe_(2)O_(3)NP embedded within porous TiO_(2)layer.Comprehensive surface characterizations with density functional theory demonstrated an improved electronic transition in TiO_(2)due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe;it also unexpectedly increased the active site in the TiO_(2)layer due to uncoordinated electrons in Sub-5 nm Fe_(2)O_(3)NP/TiO_(2)catalyst,thereby enhancing the adsorption of chemical functional groups on the catalyst.This unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol,achieving approximately 99%efficiency in 20 min without stability decay after 20 consecutive cycles,outperforming previously reported TiO_(2)-based catalysts.This finding proposes a modified-electrochemical strategy enabling facile construction of TiO_(2)with nanoscale oxides extandable to other metal oxide systems.
基金supported by the National Key Research and Development Program of China (Grant No.2018YFE0203802)Natural Science Foundation of Hubei Province, China (Grant No.2022CFA031)Dongguan Innovative Research Team Program (2020607101007)。
文摘Owing to the advantages of simple structure,low power consumption and high-density integration,memristors or memristive devices are attracting increasing attention in the fields such as next generation non-volatile memories,neuromorphic computation and data encryption.However,the deposition of memristive films often requires expensive equipment,strict vacuum conditions,high energy consumption,and extended processing times.In contrast,electrochemical anodizing can produce metal oxide films quickly(e.g.10 s) under ambient conditions.By means of the anodizing technique,oxide films,oxide nanotubes,nanowires and nanodots can be fabricated to prepare memristors.Oxide film thickness,nanostructures,defect concentrations,etc,can be varied to regulate device performances by adjusting oxidation parameters such as voltage,current and time.Thus memristors fabricated by the anodic oxidation technique can achieve high device consistency,low variation,and ultrahigh yield rate.This article provides a comprehensive review of the research progress in the field of anodic oxidation assisted fabrication of memristors.Firstly,the principle of anodic oxidation is introduced;then,different types of memristors produced by anodic oxidation and their applications are presented;finally,features and challenges of anodic oxidation for memristor production are elaborated.
基金supported by the fund of State Key Laboratory of Long-life High Temperature Materials(Grant No.DTCC28EE200787)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2022JQ-553)+3 种基金the China Postdoctoral Science Foundation(Grant No.2021M692555)the Excellent Youth Foundation of Shaanxi Province of China(Grant No.2021JC-08)the Beilin district of Xi’an Science and Technology Project(Grant No.GX2123)the support from the Youth Innovation Team of Shaanxi Universities。
文摘The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain methods.The phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and EDS.Results show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this temperature.As the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 h.Then,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 h.This internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture sublayer.Also two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 h.This internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)sublayer.Finally,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.
基金supported by the National Natural Science Foundation of China(Nos.82170426 and 22078193)Double Thousand Plan of Jiangxi Province(Nos.461654,jxsq2019102052).
文摘Electrocatalytic glucose oxidation reaction(GOR)has attracted much attention owing to its crucial role in biofuel cell fabrication.Herein,we load MoO_(3)nanoparticles on carbon nanotubes(CNTs)and use a discharge process to prepare a noblemetal-free MC-60 catalyst containing MoO_(3),Mo_(2)C,and a Mo_(2)C–MoO_(3)interface.In the GOR,MC-60 shows activity as high as 745μA/(mmol/L cm^(2)),considerably higher than those of the Pt/CNT(270μA/(mmol/L cm^(2)))and Au/CNT catalysts(110μA/(mmol/L cm^(2))).In the GOR,the response minimum on MC-60 is as low as 8μmol/L,with a steady-state response time of only 3 s.Moreover,MC-60 has superior stability and anti-interference ability to impurities in the GOR.The better performance of MC-60 in the GOR is attributed to the abundant Mo sites bonding to C and O atoms at the MoO_(3)–Mo_(2)C interface.These Mo sites create active sites for promoting glucose adsorption and oxidation,enhancing MC-60 performance in the GOR.Thus,these results help to fabricate more effi cient noble-metal-free catalysts for the fabrication of glucose-based biofuel cells.
基金financially supported by the National Key R&D Program of China(No.2021YFB3704000)the National Natural Science Foundation of China(Nos.52074032,51974029,52071013,and 52130407)+3 种基金the Beijing Natural Science Foundation(No.2232084)the Guangdong Basic and Applied Basic Research Foundation(No.2021B1515120033)the 111 Project(No.B170003)the Basic and Applied Basic Research Fund of Guangdong Province,China(No.BK20BE015).
文摘The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys.In this study,FGH96 alloy powders with various oxygen contents were investigated using high-resolution transmission electron microscopy and atomic probe technology to elucidate the structure evolution of the oxide film.Energy dispersive spectrometer analysis revealed the presence of two distinct components in the oxide film of the alloy powders:amorphous oxide layer covering the γ matrix and amorphous oxide particles above the carbide.The alloying elements within the oxide layer showed a laminated distribution,with Ni,Co,Cr,and Al/Ti,which was attributed to the decreasing oxygen equilibrium pressure as oxygen diffused from the surface into the γ matrix.On the other hand,Ti enrichment was observed in the oxide particles caused by the oxidation and decomposition of the carbide phase.Comparative analysis of the oxide film with oxygen contents of 140,280,and 340 ppm showed similar element distributions,while the thickness of the oxide film varies approximately at 9,14,and 30 nm,respectively.These findings provide valuable insights into the structural analysis of the oxide film on FGH96 alloy powders.
基金the SINOPEC(124015)and the State Key Laboratory of Engines at Tianjin University(No.K2022-06).
文摘The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were collected by a thermophoretic system and a quartz filter.The oxidation reactivity,oxidation behaviors,and physicochemical properties of the PM samples were analyzed using thermogravimetric analysis(TGA),high-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectrometry(FTIR),and Raman spectroscopy.The results showed that there was a great difference in the oxidation reactivity of soot particles emitted by the two different diesel engines.A qualitative analysis of the factors influencing oxidation reactivity showed that the nanostructure,degree of graphitization,and relative concentration of aliphatic C—H functional groups were the most important factors,whereas no significant correlation was found between the primary particle size and activation energy of the diesel soot.Based on the oxidation behavior analysis,the diesel soot particles exhibited both internal and surface oxidation modes during the oxidation process.Surface oxidation was dominant during the initial stage,and as oxidation progressed,the mode gradually changed to internal oxidation.Internal oxidation mode of soot particles from the 1K engine was significantly higher than that of CY4102.
文摘Utilizing single atom sites doping into metal oxides to modulate their intrinsic active sites,achieving precise selectivity control in complex organic reactions,is a highly desirable yet challenging endeavor.Meanwhile,identifying the active site also represents a significant obstacle,primarily due to the intricate electronic environment of single atom site doped metal oxide.Herein,a single atom Cu doped TiO_(2)catalyst(Cu_(1)-TiO_(2))is prepared via a simple“colloid-acid treatment”strategy,which switches aniline oxidation selectivity of TiO_(2)from azoxybenzene to nitrosobenzene,without using additives or changing solvent,while other metal or nonmetal doped TiO_(2)did not possess.Comprehensive mechanistic investigations and DFT calculations unveil that Ti-O active site is responsible for triggering the aniline to form a new PhNOH intermediate,two PhNOH condense to azoxybenzene over TiO_(2)catalyst.As for Cu_(1)-TiO_(2),the charge-specific distribution between the isolated Cu and TiO_(2)generates unique Cu_(1)-O-Ti hybridization structure with nine catalytic active sites,eight of them make PhNOH take place spontaneous dissociation to produce nitrosobenzene.This work not only unveils a new mechanistic pathway featuring the PhNOH intermediate in aniline oxidation for the first time but also presents a novel approach for constructing single-atom doped metal oxides and exploring their intricate active sites.
基金funded by China Postdoctoral Science Foundation(No.2021M700569)Chongqing Postdoctoral Science Foundation(No.7 cstc2021jcyj-bshX0087)。
文摘This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/Na2SiO3electrolyte.The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic polarization.It was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and dispersed.The nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in grains.It effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge pores.The MAO coating on Zr-FSP sample had good wettability and corrosion resistance.However,TiO_(2)particles were hardly detected in the coating on TiFSP sample.
文摘Chromia-forming alloys have good resistance to oxidizing agents such as O2, CO2, … It is accepted that the protection of these alloys is always due to the chromia layer formed at the surface of the alloys, which acts as a barrier between the oxidizing gases and the alloy substrates, forming a diffusion zone that limits the overall reaction rate and leads to parabolic kinetics. But this was not verified in the study devoted to Inconel®625 the oxidation in CO2 that was followed by TGA, with characterizations by XRD, EDS and FIB microscopy. Contrary to what was expected and accepted in similar studies on other chromia-forming alloys, it was shown that the diffusion step that governs the overall reaction rate is not located inside the chromia layer but inside the alloy, precisely inside a zone just beneath the interface alloy/chromia, this zone being depleted in chromium. The chromia layer, therefore, plays no kinetic role and does not directly protect the underlying alloy. This result was demonstrated using a simple test that consisted in removing the chromia layer from the surface of samples partially oxidized and then to continue the thermal treatment: insofar as the kinetics continued without any change in rate, this proved that this surface layer of oxide did not protect the substrate. Based on previous work on many chromia-forming alloys, the possibility of a similar reaction mechanism is discussed. If the chromia layer is not the source of protection for a number of chromia-forming alloys, as is suspected, this might have major consequences in terms of industrial applications.
基金supported by the National Natural Science Foundation of China(Nos.52331005,52201100,52171095,and 92060113)the China Postdoctoral Science Foundation(No.2022M710346)+2 种基金Science and Technology on Advanced High Temperature Structural Materials Laboratory,China(No.6142903210207)the Fundamental Research Funds for the Central Universities,China(No.FRF-GF-20-30B)the National Key Research and Development Program of China(No.2017YFB0702902).
文摘A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared,and the evaluation of its high-temperature microstructural stability,oxidation resistance,and mechanical properties was conducted mainly using its cast polycrystalline alloy.The results disclosed that the morphology of theγ′phase remained stable,and the coarsening rate was slow during the long-term aging at 900–1000℃.The activation energy forγ′precipitate coarsening of alloy 9CoNi-Cr was(402±51)kJ/mol,which is higher compared with those of CMSX-4 and some other Ni-based and Co-based superalloys.Importantly,there was no indica-tion of the formation of topologically close-packed phases during this process.All these factors demonstrated the superior microstructural stability of the alloy.The mass gain of alloy 9CoNi-Cr was 0.6 mg/cm^(2) after oxidation at 1000℃ for 100 h,and the oxidation resistance was comparable to advanced Ni-based superalloys CMSX-4,which can be attributed to the formation of a continuous Al_(2)O_(3) protective layer.Moreover,the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950℃ is comparable to that of the conventional Ni-based cast superalloy,demonstrating the alloy’s good mechanical properties at high temperature.This is partially because high Cr is bene-ficial in improving theγandγ′phase strengths of alloy 9CoNi-Cr.
基金financial support from the National Natural Science Foundation of China(22178154,22008094,21908082,21878133)Natural Science Foundation of Jiangsu Province(BK20190852,BK20190854)Natural Science Foundation for Jiangsu Colleges and Universities(19KJB530005).
文摘A few-layered hexagonal boron nitride nanosheets stabilized platinum nanoparticles(Pt/h-BNNS)is engineered for oxidation-promoted adsorptive desulfurization(OPADS)of fuel oil.It was found that the few-layered structure and the defective sites of h-BNNS not only are beneficial to the stabilization of Pt NPs but also favor the adsorption of aromatic sulfides.By employing Pt/h-BNNS with a Pt loading amount of 1.19 wt%as the active adsorbent and air as an oxidant,a 98.0%sulfur removal over dibenzothiophene(DBT)is achieved along with a total conversion of the DBT to the corresponding sulfones(DBTO_(2)).Detailed experiments show that the excellent desulfurization activity originates from the few-layered structure of h-BNNS and the high catalytic activity of Pt NPs.In addition,the OPADS system with Pt/h-BNNS as the active adsorbent shows remarkable stability in desulfurization performance with the existence of different interferents such as olefin,and aromatic hydrocarbons.Besides,the Pt/h-BNNS can be recycled 12 times without a significant decrease in desulfurization performance.Also,a process flow diagram is proposed for deep desulfurization of fuel oil and recovery of high value-added products,which would promote the industrial application of such OPADS strategy.