To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,...Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.展开更多
Effective control of gas-phase pollutants(volatile organic compounds(VOCs)and CO)is critical to human health and the ecological environment.Catalytic oxidation is one of the most promising technologies for achieving e...Effective control of gas-phase pollutants(volatile organic compounds(VOCs)and CO)is critical to human health and the ecological environment.Catalytic oxidation is one of the most promising technologies for achieving efficient volatile organic compounds and CO emission control.The subnano cluster catalyst can not only provide catalytic sites with multiple metal atoms,but also maintain full utilization efficiency.Almost all metal atoms in highly dispersed clusters can be used for adsorption and conversion of reactants.Recently,various types of sub-nano clusters,including subnano cluster oxides,have been developed and demonstrated excellent performance in low-temperature gas-phase pollutants combustion.In this mini review,we systematically summarize the structure,physicochemical properties,characterization,and applications of sub-nano cluster catalysts in catalytic oxidation of CO,methane,propane,propylene,toluene and its derivatives,formaldehyde and chlorinated volatile organic compounds.Finally,we have analyzed and discussed the problems and challenges faced by sub-nano cluster catalysts in both basic research and practical applications,providing a scientific basis for the design,synthesis,and application of efficient heterogeneous catalysts for CO and VOCs oxidation.展开更多
Methanol oxidation reaction(MOR)is a key process in direct methanol fuel cells(DMFCs),determining both energy efficiency and stability.Despite efforts,the impact of dynamic structural changes of Pt-based catalysts on ...Methanol oxidation reaction(MOR)is a key process in direct methanol fuel cells(DMFCs),determining both energy efficiency and stability.Despite efforts,the impact of dynamic structural changes of Pt-based catalysts on MOR performance remains poorly understood.Here,we report on the impact mechanism of dynamic changes on MOR performance in the Pd-Pt concave nanocubes(CNCs)system.Pt with high-index facets exposed abundant active sites for methanol oxidation,resulting in an exceptional mass activity of 0.89 A·mg_(Pt)^(-1).Pd underwent an oxidationredeposition process during MOR,dynamically restructuring the catalyst and producing a volcano-type activity.Pd^(δ+)species generated during oxidative etching promoted OH*formation,accelerating CO oxidation on Pt sites,thus mitigating poisoning.With continued cycling,redeposited Pd partially blocked Pt sites,counteracting the positive effect of the generated Pd^(δ+).The dynamic balance of Pd oxidation and redeposition governed the activity evolution while sustaining the exceptional durability of Pd-Pt CNCs during prolonged cycling.展开更多
In this work,we constructed a three-dimensional electrochemical system(3D-ECO),which included the cathode and anode electrode plates,as well as the screening of three-dimensional particle electrodes and parameter opti...In this work,we constructed a three-dimensional electrochemical system(3D-ECO),which included the cathode and anode electrode plates,as well as the screening of three-dimensional particle electrodes and parameter opti-mization,for the degradation of landfill leachate(LL)containing elevated levels of tetracycline(TC),and explored its mechanism of action.Firstly,titanium-based ruthenium-iridium(Ti/RuO_(2)-IrO_(2)),titanium-based ruthenium-iridium-platinum(Ti/Pt-RuO_(2)-IrO_(2)),and titanium-based tin-antimony(Ti/SnO_(2)-Sb_(2)O_(3))were employed as an-odes in the electrocatalytic oxidation system,with titanium and stainless steel plates serving as cathodes,to construct the optimal two-dimensional electrocatalytic oxidation system(2D-ECO)through cross-comparison ex-periments.Subsequently,using granular activated carbon(GAC),coconut shell biochar(CBC),walnut shell carbon(WBC),and bamboo charcoal(BBC)as particle electrodes,a 3D-ECO system was developed.The influence of var-ious operational parameters on treating TC-containing LL was investigated.The optimal operating parameters obtained from the study was:pH=5,current density of 30 mA/cm^(2),particle dosage of 7 g/L,particle size ranging from 1.70 to 2.00 mm,and electrode spacing of 4 cm.Under these conditions,the COD removal rate of 3D-ECO within three hours was 90.25%,the TC removal rate was 72.41%,and the NH_(3)-N removal rate was 39.52%.The removal of TC followed a pseudo-first-order kinetic model.Additionally,degradation mechanisms were elucidated through electron paramagnetic resonance(EPR)spectrometer and Tert-Butanol(TBA)quenching experiments,indicating that the degradation primarily occurred through a non-radical(1O_(2))pathway.This re-search offers a comprehensive analysis of the simultaneous breakdown of intricate LL matrices and TC,enhancing our comprehension of the degradation processes and underlying mechanisms.展开更多
Co-based materials usually undergo in-situ surface reconstruction during oxidation reactions,forming high-valent Co_(3)+/Co4+species as the true active sites.However,conventional bulk structures of Co-based materials ...Co-based materials usually undergo in-situ surface reconstruction during oxidation reactions,forming high-valent Co_(3)+/Co4+species as the true active sites.However,conventional bulk structures of Co-based materials hinder deep phase transformation,limiting the utilization of internal Co sites and suppressing catalytic efficiency.Here,we report the hollow engineering of cobalt phosphide(CoP)to facilitate exposure of Co sites and promote in-situ transformation to Co_(3+)/Co^(4+)active species for enhanced oxidation activity.Hollow CoP(H-CoP)is derived from ZIF-67 via controlled etching and phosphorization,with electrochemically active surface area 2.1 times that of conventional solid CoP(S-CoP).H-CoP achieves a current density of 10 mA·cm^(-2) at a lower potential(1.26 V vs.reversible hydrogen electrode(RHE))in 5-hydroxymethylfurfural oxidation reaction(HMFOR),with a HMF conversion of 99.5%,2,5-furandicarboxylic acid yield of 98.6%,and Faraday efficiency of 97.5% at 1.45 V(vs.RHE),much superior to S-CoP.When applied as a bifunctional catalyst in the HMFOR coupled with hydrogen evolution reaction(HER)electrolyzer,H-CoP requires an ultralow voltage of 1.64 V to reach 10 mA·cm^(-2),with the cell voltage reduced by 190 mV compared to the conventional oxygen evolution reaction coupled with HER water splitting system.展开更多
Constructing catalysts featuring an ordered structure,stable performance,and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins.Here,we design catalysts by tracing the oxidatio...Constructing catalysts featuring an ordered structure,stable performance,and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins.Here,we design catalysts by tracing the oxidationprocess origin and synthesize a series of highly dispersed metal porphyrin-based covalent organic frameworks(COFs)materials.The aim is to efficiently oxidize the C-H bonds of cumene by air to in-situ generate organic peroxides at a safe concentration,and integrate the multi-step oxidation method of cumene in industry into a one-step method for olefins’epoxidation.The carbonyl-ruthenium COF(Ru-COF-1)exhibits excellent performance,with 98% epoxide selectivity,1221.77 h^(-1) productivity,and over 95% selectivity after 9 cycles for 1-hexene.Analysis of structure-properties-catalytic relationships of Ru-COF-1 shows that,compared with Ru-porphyrins and metal-free COFs,the enhanced reaction performance mainly results from Ru metal introduction,which promotes benzylic proton transfer in cumene.Besides,Ru-COF-1’s porous,ordered structure aids oxygen enrichment,forming active peroxy radicals with the cumene carboncentered radicals formed on the catalyst surface.Ru-H sites then accelerate active oxygen transfer from peroxy radicals,enabling olefin tandem epoxidation.Density functional theory(DFT)calculations verify the reaction mechanism,and this work offers a reference for the design of catalysts for the green,safe,and efficient oxidation of olefins.展开更多
TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
Investigating structural and hydroxyl group effects in electrooxidation of alcohols to value-added products by solid-acid electrocatalysts is essential for upgrading biomass alcohols.Herein,we report efficient electro...Investigating structural and hydroxyl group effects in electrooxidation of alcohols to value-added products by solid-acid electrocatalysts is essential for upgrading biomass alcohols.Herein,we report efficient electrocatalytic oxidations of saturated alcohols(C_(1)-C_(6))to selectively form formate using Ni Co hydroxide(Ni Co-OH)derived Ni Co_(2)O_(4)solid-acid electrocatalysts with balanced Lewis acid(LASs)and Brønsted acid sites(BASs).Thermal treatment transforms BASs-rich(89.6%)Ni Co-OH into Ni Co_(2)O_(4)with nearly equal distribution of LASs(53.1%)and BASs(46.9%)which synergistically promote adsorption and activation of OH-and alcohol molecules for enhanced oxidation activity.In contrast,BASs-enriched Ni Co-OH facilitates formation of higher valence metal sites,beneficial for water oxidation.The combined experimental studies and theoretical calculation imply the oxidation ability of C1-C6alcohols increases as increased number of hydroxyl groups and decreased HOMO-LUMO gaps:methanol(C_(1))<ethylene glycol(C_(2))<glycerol(C3)<meso-erythritol(C4)<xylitol(C5)<sorbitol(C6),while the formate selectivity shows the opposite trend from 100 to 80%.This study unveils synergistic roles of LASs and BASs,as well as hydroxyl group effect in electro-upgrading of alcohols using solid-acid electrocatalysts.展开更多
Up-and-coming high-temperature materials,refractory high entropy alloys,are suffering from lower oxidation resistance,restricting their applications in the aerospace field.In this study,two novel treatments of Al-depo...Up-and-coming high-temperature materials,refractory high entropy alloys,are suffering from lower oxidation resistance,restricting their applications in the aerospace field.In this study,two novel treatments of Al-deposited and remelted were developed to refine the microstructure and enhance the oxidation resistance of refractory high entropy alloy using electron beam freeform fabrication(EBF3).Finer and short-range ordering structures were observed in the remelted sample,whereas the Al-deposited sample showcased the formation of silicide and intermetallic phases.High-temperature cyclic and isothermal oxidation tests at 1000℃ were carried out.The total weight gain after 60 h of cyclic oxidation decreased by 17.49%and 30.46%for the remelted and deposited samples,respectively,compared to the as-cast state.Oxidation kinetics reveal an evident lower mass gain and oxidation rate in the treated samples.A multilayer oxide consisting of TiO_(2)+Al_(2)O_(3)+SiO_(2)+AlNbO_(4) was studied for its excellent oxidation resistance.The oxidation behavior of rutile,corundum and other oxides was analyzed using first principles calculations and chemical defect analysis.Overall,this research,which introduces novel treatments,offers promising insights for enhancing the inherent oxidation resistance of refractory high entropy alloys.展开更多
Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation ac...Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation activity were studied.Several different carbon materi-als were produced from them by oxida-tion in air(350℃,300 mL/min)fol-lowed by carbonization(1000℃ in Ar),and the effect of the cross-linked structure on their structure and sodium storage properties was investigated.The results showed that the two pitch fractions were obviously different after the air oxidation.The TS fraction with a low degree of condensation and abundant side chains had a stronger oxidation activity and thus introduced more cross-linked oxygen-containing functional groups C(O)―O which prevented carbon layer rearrangement during the carbonization.As a result,a disordered hard carbon with more defects was formed,which improved the electrochemical performance.Therefore,the carbon materials derived from TS(O-TS-1000)had an obvious disordered structure and a larger layer spacing,giving them better sodium storage perform-ance than those derived from the TI-PS fraction(O-TI-PS-1000).The specific capacity of O-TS-1000 was about 250 mAh/g at 20 mA/g,which was 1.67 times higher than that of O-TI-PS-1000(150 mAh/g).展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review present...The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review presents an overview of the research progress on oxidation behavior of Co-based superalloys, including oxidation kinetics, oxides morphology, the formation and spallation of oxide layers, and importantly, the synergistic effects of alloying elements on oxidation resistance—a critical area considering the complex interactions with multiple alloying elements. Additionally, this review compares the oxidation resistance of single crystal versus polycrystalline alloys. The effect of phase interface and dislocations on oxidation behavior is also discussed. While significant progress has been achieved, areas necessitating further investigation include optimizing alloy compositions for enhanced oxidation resistance and understanding the long-term stability of oxide layers. The future prospects for Co-based superalloys are promising as ongoing research aims to address the existing challenges and unlock new applications at even higher operating temperatures.展开更多
Traumatic brain injury involves complex pathophysiological mechanisms,among which oxidative stress significantly contributes to the occurrence of secondary injury.In this study,we evaluated hypidone hydrochloride(YL-0...Traumatic brain injury involves complex pathophysiological mechanisms,among which oxidative stress significantly contributes to the occurrence of secondary injury.In this study,we evaluated hypidone hydrochloride(YL-0919),a self-developed antidepressant with selective sigma-1 receptor agonist properties,and its associated mechanisms and targets in traumatic brain injury.Behavioral experiments to assess functional deficits were followed by assessment of neuronal damage through histological analyses and examination of blood-brain barrier permeability and brain edema.Next,we investigated the antioxidative effects of YL-0919 by assessing the levels of traditional markers of oxidative stress in vivo in mice and in vitro in HT22 cells.Finally,the targeted action of YL-0919 was verified by employing a sigma-1 receptor antagonist(BD-1047).Our findings demonstrated that YL-0919 markedly improved deficits in motor function and spatial cognition on day 3 post traumatic brain injury,while also decreasing neuronal mortality and reversing blood-brain barrier disruption and brain edema.Furthermore,YL-0919 effectively combated oxidative stress both in vivo and in vitro.The protective effects of YL-0919 were partially inhibited by BD-1047.These results indicated that YL-0919 relieved impairments in motor and spatial cognition by restraining oxidative stress,a neuroprotective effect that was partially reversed by the sigma-1 receptor antagonist BD-1047.YL-0919 may have potential as a new treatment for traumatic brain injury.展开更多
Engineering nanomaterials at single-atomic sites could enable unprecedented catalytic properties for broad applications,yet it remains challenging to do so on the surface of multimetallic nanocrystals.Herein,we presen...Engineering nanomaterials at single-atomic sites could enable unprecedented catalytic properties for broad applications,yet it remains challenging to do so on the surface of multimetallic nanocrystals.Herein,we present the multifactorial engineering(size,shape,phase,and composition)of the fully ordered PtBi nanoplates at atomic level,achieving a unique catalyst surface where the face-centered cubic(fcc)Pt edges are modified by the isolated Pd atoms and BiO_(x)adatoms.This Pd_(1)/Pt-BiO_(x)electrocatalyst exhibits an ultrahigh mass activity of 16.01 A mg^(-1)Pt+Pd toward ethanol oxidation in alkaline electrolyte and enables a direct ethanol fuel cell of peak power density of 56.7 mW cm^(−2).The surrounding BiO_(x)adatoms are critical for mitigating CO-poisoning on the Pt surface,and the Pd_(1)/Pt single-atom alloy further facilitates the electrooxidation of CH_(3)CH_(2)OH.This work offers new insights into the rational design and construction of sophisticated catalyst surface at single-atomic sites for highly efficient electrocatalysis.展开更多
Magnesium matrix composites with both high strength and ductility have been achieved by introducing pure Ti particles.However,the properties of the surfaces of the composites need to be improved by surface technology,...Magnesium matrix composites with both high strength and ductility have been achieved by introducing pure Ti particles.However,the properties of the surfaces of the composites need to be improved by surface technology,such as micro-arc oxidation(MAO).In this study,we investigated the influence of the Ti-reinforcement phase on coating growth and evolution by subjecting both AZ91 alloy and AZ91/Ti composite to MAO treatment using silicate-based and phosphate-based electrolytes.Results revealed that the Ti-reinforcement phase influenced the MAO process,altering discharge behavior,and leading to a decreased cell voltage.The vigorous discharge of the Ti-reinforcement phase induced the formation of coating discharge channels,concurrently dissolving and oxidizing Ti-reinforcement to produce a composite ceramic coating with TiO2.The MAO coating on the AZ91/Ti composite exhibited a dark blue macromorphology and distinctive local micromorphological anomalies.In silicate electrolyte,a“volcano-like”localized morphology centered on the discharge channel emerged.In contrast,treatment in phosphate-based electrolyte resulted in a coating morphology similar to typical porous ceramic coatings,with visible radial discharge micropores at the reinforcement phase location.Compared to the AZ91 alloy,the coating on the AZ91/Ti composite exhibited lower thickness and higher porosity.MAO treatment reduced the self-corrosion current density of the AZ91/Ti surface by two orders of magnitude.The silicate coating demonstrated better corrosion resistance than the phosphate coating,attributed to its lower porosity.The formation mechanism of MAO coatings on AZ91/Ti composites in phosphate-based and silicate-based electrolytes was proposed.展开更多
Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates...Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates the preparation of ZnO-containing micro-arc oxidation coatings with dual functionality by incorporating nano-ZnO into MAO electrolyte.The influence of varying ZnO concentrations on the microstructure,corrosion resistance,and antibacterial properties of the coating was examined through microstructure analysis,immersion tests,electrochemical experiments,and antibacterial assays.The findings revealed that the addition of nano-ZnO significantly enhanced the corrosion resistance of the MAO-coated alloy.Specifically,when the ZnO concentration in the electrolyte was 5 g/L,the corrosion rate was more than ten times lower compared to the MAO coatings without ZnO.Moreover,the antibacterial efficacy of ZnO+MAO coating,prepared with a ZnO concentration of 5 g/L,surpassed 95%after 24 h of co-culturing with Staphylococcus aureus(S.aureus).The nano-ZnO+MAO-coated alloy exhibited exceptional degradation resistance,corrosion resistance,and antibacterial effectiveness.展开更多
A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion du...A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding,consisting of outermost Cr layer and CoNiCrAlTaY transition layer.The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K.The top Cr_(2)O_(3)film and spinel oxides(i.e.,NiCr_(2)O_(4)and CoCr_(2)O_(4))exhibited a protective effect with a low oxidation reaction rate.Interfacial analysis identified Ta precipitates(Cr_(2)Ta and TaAl_(3))and Ta oxides(Ta_(2)O_(5)and Ta_(2)O_(3)),which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.展开更多
This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol(8HQ)molecules and the poro...This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol(8HQ)molecules and the porous MgO layer formed via plasma electrolytic oxidation(PEO).The AZ31 Mg alloy,initially coated with a PEO layer,underwent a dipping treatment in an ethanolic solution of 0.05 M 8HQ at 50℃ for 3 h.The results were compared with those from a different procedure where the PEO layer was subjected to a hydration reaction for 2 h at 90℃ before immersion in the 8HQ solution under the same conditions.The hydration treatment played a crucial role by converting MgO to Mg(OH)_(2),significantly enhancing the surface reactivity.This transformation introduced hydroxyl groups(−OH)on the surface,which facilitated donor-acceptor interactions with the electron-accepting sites on 8HQ molecules.The calculated binding energy(Ebinding)from DFT indicated that the interaction energy of 8HQ with Mg(OH)_(2) was lower compared to 8HQ with MgO,suggesting easier adsorption of 8HQ molecules on the hydrated surface.This,combined with the increased number of active sites and enhanced surface area,allowed for extensive surface coverage by 8HQ,leading to the formation of a stable,flake-like protective layer that sealed the majority of pores on the PEO layer.DFT calculations further suggested that the hydration treatment provided multiple active sites,enabling effective contact with 8HQ and rapid electron transfer,creating ideal conditions for charge-transfer-induced physical and chemical bonding.This study shows that hydration and 8HQ treatments significantly enhance the corrosion resistance of Mg alloys,highlighting their potential for advanced anticorrosive coatings.展开更多
Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy.However,the long-term protective property of single silicide coating remains a long-time endeavor ...Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy.However,the long-term protective property of single silicide coating remains a long-time endeavor due to the deficiency of oxygen-consuming phases,as well as the self-healing ability of the protective layer.Herein,a silicide-based composite coating is constructed on niobium alloy by incor-poration of nano-SiC particles for enhancing the high-temperature oxidation resistance.Isothermal oxi-dation results at 1250℃ for 50 h indicate that NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multilayer coated sample with a low mass gain of 2.49 mg/cm^(2) shows an improved oxidation resistance compared with NbSi_(2) coating(6.49 mg/cm^(2)).The enhanced high-temperature antioxidant performance of NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multi-layer coating is mainly attributed to the formation of the protective SiO_(2) self-healing film and the high-temperature diffusion behavior of NbSi_(2)/substrate.展开更多
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金supported by the National Key Research and Development Program of China(2024YFA1612900)the National Natural Science Foundation of China(Grant No.52103365 and No.12375270)the Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2021ZT09L227).
文摘Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.
基金supported by the National Natural Science Foundation of China(No.22506042)the Natural Science Foundation of Henan Province(Nos.252300421710 and 252300421552)the High level Talent Research Launch Fund of Henan University of Technology(No.2024BS061).
文摘Effective control of gas-phase pollutants(volatile organic compounds(VOCs)and CO)is critical to human health and the ecological environment.Catalytic oxidation is one of the most promising technologies for achieving efficient volatile organic compounds and CO emission control.The subnano cluster catalyst can not only provide catalytic sites with multiple metal atoms,but also maintain full utilization efficiency.Almost all metal atoms in highly dispersed clusters can be used for adsorption and conversion of reactants.Recently,various types of sub-nano clusters,including subnano cluster oxides,have been developed and demonstrated excellent performance in low-temperature gas-phase pollutants combustion.In this mini review,we systematically summarize the structure,physicochemical properties,characterization,and applications of sub-nano cluster catalysts in catalytic oxidation of CO,methane,propane,propylene,toluene and its derivatives,formaldehyde and chlorinated volatile organic compounds.Finally,we have analyzed and discussed the problems and challenges faced by sub-nano cluster catalysts in both basic research and practical applications,providing a scientific basis for the design,synthesis,and application of efficient heterogeneous catalysts for CO and VOCs oxidation.
基金supported by the National Natural Science Foundation of China(Nos.12222508 and 12475325)the National Key Research and Development Program of China(Nos.2024YFA1509201 and 2023YFA1506304)the beamlines BL10B(No.31131.02.HLS.PES)and BL01B(No.31131.02.HLS.IRSM)in NSRL,and BL11B(No.31124.02.SSRF.BL11B)in SSRF for synchrotron radiation measurements.
文摘Methanol oxidation reaction(MOR)is a key process in direct methanol fuel cells(DMFCs),determining both energy efficiency and stability.Despite efforts,the impact of dynamic structural changes of Pt-based catalysts on MOR performance remains poorly understood.Here,we report on the impact mechanism of dynamic changes on MOR performance in the Pd-Pt concave nanocubes(CNCs)system.Pt with high-index facets exposed abundant active sites for methanol oxidation,resulting in an exceptional mass activity of 0.89 A·mg_(Pt)^(-1).Pd underwent an oxidationredeposition process during MOR,dynamically restructuring the catalyst and producing a volcano-type activity.Pd^(δ+)species generated during oxidative etching promoted OH*formation,accelerating CO oxidation on Pt sites,thus mitigating poisoning.With continued cycling,redeposited Pd partially blocked Pt sites,counteracting the positive effect of the generated Pd^(δ+).The dynamic balance of Pd oxidation and redeposition governed the activity evolution while sustaining the exceptional durability of Pd-Pt CNCs during prolonged cycling.
基金supported by the National Natural Science Foundation of China(Nos.42477406 and 51878617)the Horizontal Scientific Research Project(No.KYY-HX-20220803)the Engineering Research Center of Ministry of Education for Renewable Energy Infrastructure Construction Technology.
文摘In this work,we constructed a three-dimensional electrochemical system(3D-ECO),which included the cathode and anode electrode plates,as well as the screening of three-dimensional particle electrodes and parameter opti-mization,for the degradation of landfill leachate(LL)containing elevated levels of tetracycline(TC),and explored its mechanism of action.Firstly,titanium-based ruthenium-iridium(Ti/RuO_(2)-IrO_(2)),titanium-based ruthenium-iridium-platinum(Ti/Pt-RuO_(2)-IrO_(2)),and titanium-based tin-antimony(Ti/SnO_(2)-Sb_(2)O_(3))were employed as an-odes in the electrocatalytic oxidation system,with titanium and stainless steel plates serving as cathodes,to construct the optimal two-dimensional electrocatalytic oxidation system(2D-ECO)through cross-comparison ex-periments.Subsequently,using granular activated carbon(GAC),coconut shell biochar(CBC),walnut shell carbon(WBC),and bamboo charcoal(BBC)as particle electrodes,a 3D-ECO system was developed.The influence of var-ious operational parameters on treating TC-containing LL was investigated.The optimal operating parameters obtained from the study was:pH=5,current density of 30 mA/cm^(2),particle dosage of 7 g/L,particle size ranging from 1.70 to 2.00 mm,and electrode spacing of 4 cm.Under these conditions,the COD removal rate of 3D-ECO within three hours was 90.25%,the TC removal rate was 72.41%,and the NH_(3)-N removal rate was 39.52%.The removal of TC followed a pseudo-first-order kinetic model.Additionally,degradation mechanisms were elucidated through electron paramagnetic resonance(EPR)spectrometer and Tert-Butanol(TBA)quenching experiments,indicating that the degradation primarily occurred through a non-radical(1O_(2))pathway.This re-search offers a comprehensive analysis of the simultaneous breakdown of intricate LL matrices and TC,enhancing our comprehension of the degradation processes and underlying mechanisms.
基金the National Natural Science Foundation of China(Nos.22422806,22378136,and 22138003)the Guangdong Pearl River Talents Program(Nos.2021QN02C847 and 2021ZT09Z109)+4 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515011196 and 2023B1515040005)the Guangzhou Municipal Science and Technology Project(No.2025A04J5244)the Fundamental Research Funds for the Central Universities(No.2024ZYGXZR011)the State Key Laboratory of Pulp and Paper Engineering(Nos.2023PY06 and 2024ZD09)the TCL Young Talent Program.
文摘Co-based materials usually undergo in-situ surface reconstruction during oxidation reactions,forming high-valent Co_(3)+/Co4+species as the true active sites.However,conventional bulk structures of Co-based materials hinder deep phase transformation,limiting the utilization of internal Co sites and suppressing catalytic efficiency.Here,we report the hollow engineering of cobalt phosphide(CoP)to facilitate exposure of Co sites and promote in-situ transformation to Co_(3+)/Co^(4+)active species for enhanced oxidation activity.Hollow CoP(H-CoP)is derived from ZIF-67 via controlled etching and phosphorization,with electrochemically active surface area 2.1 times that of conventional solid CoP(S-CoP).H-CoP achieves a current density of 10 mA·cm^(-2) at a lower potential(1.26 V vs.reversible hydrogen electrode(RHE))in 5-hydroxymethylfurfural oxidation reaction(HMFOR),with a HMF conversion of 99.5%,2,5-furandicarboxylic acid yield of 98.6%,and Faraday efficiency of 97.5% at 1.45 V(vs.RHE),much superior to S-CoP.When applied as a bifunctional catalyst in the HMFOR coupled with hydrogen evolution reaction(HER)electrolyzer,H-CoP requires an ultralow voltage of 1.64 V to reach 10 mA·cm^(-2),with the cell voltage reduced by 190 mV compared to the conventional oxygen evolution reaction coupled with HER water splitting system.
基金financially supported by the National Natural Science Foundation of China(No.22508360)Zhejiang Provincial Natural Science Foundation of China(No.QN26B060028)+1 种基金the National Key Research and Development Program Nanotechnology Specific Project(No.2020YFA0210900)Innovative Team Project of Guang-dong Ordinary University(No.2019KCXTD002).
文摘Constructing catalysts featuring an ordered structure,stable performance,and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins.Here,we design catalysts by tracing the oxidationprocess origin and synthesize a series of highly dispersed metal porphyrin-based covalent organic frameworks(COFs)materials.The aim is to efficiently oxidize the C-H bonds of cumene by air to in-situ generate organic peroxides at a safe concentration,and integrate the multi-step oxidation method of cumene in industry into a one-step method for olefins’epoxidation.The carbonyl-ruthenium COF(Ru-COF-1)exhibits excellent performance,with 98% epoxide selectivity,1221.77 h^(-1) productivity,and over 95% selectivity after 9 cycles for 1-hexene.Analysis of structure-properties-catalytic relationships of Ru-COF-1 shows that,compared with Ru-porphyrins and metal-free COFs,the enhanced reaction performance mainly results from Ru metal introduction,which promotes benzylic proton transfer in cumene.Besides,Ru-COF-1’s porous,ordered structure aids oxygen enrichment,forming active peroxy radicals with the cumene carboncentered radicals formed on the catalyst surface.Ru-H sites then accelerate active oxygen transfer from peroxy radicals,enabling olefin tandem epoxidation.Density functional theory(DFT)calculations verify the reaction mechanism,and this work offers a reference for the design of catalysts for the green,safe,and efficient oxidation of olefins.
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金the financial support from the National Natural Science Foundation of China(52172110,52472231,52311530113)Shanghai"Science and Technology Innovation Action Plan"intergovernmental international science and technology cooperation project(23520710600)+1 种基金Science and Technology Commission of Shanghai Municipality(22DZ1205600)the Central Guidance on Science and Technology Development Fund of Zhejiang Province(2024ZY01011)。
文摘Investigating structural and hydroxyl group effects in electrooxidation of alcohols to value-added products by solid-acid electrocatalysts is essential for upgrading biomass alcohols.Herein,we report efficient electrocatalytic oxidations of saturated alcohols(C_(1)-C_(6))to selectively form formate using Ni Co hydroxide(Ni Co-OH)derived Ni Co_(2)O_(4)solid-acid electrocatalysts with balanced Lewis acid(LASs)and Brønsted acid sites(BASs).Thermal treatment transforms BASs-rich(89.6%)Ni Co-OH into Ni Co_(2)O_(4)with nearly equal distribution of LASs(53.1%)and BASs(46.9%)which synergistically promote adsorption and activation of OH-and alcohol molecules for enhanced oxidation activity.In contrast,BASs-enriched Ni Co-OH facilitates formation of higher valence metal sites,beneficial for water oxidation.The combined experimental studies and theoretical calculation imply the oxidation ability of C1-C6alcohols increases as increased number of hydroxyl groups and decreased HOMO-LUMO gaps:methanol(C_(1))<ethylene glycol(C_(2))<glycerol(C3)<meso-erythritol(C4)<xylitol(C5)<sorbitol(C6),while the formate selectivity shows the opposite trend from 100 to 80%.This study unveils synergistic roles of LASs and BASs,as well as hydroxyl group effect in electro-upgrading of alcohols using solid-acid electrocatalysts.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0609000)National Natural Science Foundation of China(Grant Nos.52171034 and 52101037)Postdoctoral Fellowship Program of CPSFara(No.GZB20230944).
文摘Up-and-coming high-temperature materials,refractory high entropy alloys,are suffering from lower oxidation resistance,restricting their applications in the aerospace field.In this study,two novel treatments of Al-deposited and remelted were developed to refine the microstructure and enhance the oxidation resistance of refractory high entropy alloy using electron beam freeform fabrication(EBF3).Finer and short-range ordering structures were observed in the remelted sample,whereas the Al-deposited sample showcased the formation of silicide and intermetallic phases.High-temperature cyclic and isothermal oxidation tests at 1000℃ were carried out.The total weight gain after 60 h of cyclic oxidation decreased by 17.49%and 30.46%for the remelted and deposited samples,respectively,compared to the as-cast state.Oxidation kinetics reveal an evident lower mass gain and oxidation rate in the treated samples.A multilayer oxide consisting of TiO_(2)+Al_(2)O_(3)+SiO_(2)+AlNbO_(4) was studied for its excellent oxidation resistance.The oxidation behavior of rutile,corundum and other oxides was analyzed using first principles calculations and chemical defect analysis.Overall,this research,which introduces novel treatments,offers promising insights for enhancing the inherent oxidation resistance of refractory high entropy alloys.
文摘Pitch produced by the lique-faction of coal was divided into two frac-tions:soluble in toluene(TS)and insol-uble in toluene but soluble in pyridine(TI-PS),and their differences in molecu-lar structure and oxidation activity were studied.Several different carbon materi-als were produced from them by oxida-tion in air(350℃,300 mL/min)fol-lowed by carbonization(1000℃ in Ar),and the effect of the cross-linked structure on their structure and sodium storage properties was investigated.The results showed that the two pitch fractions were obviously different after the air oxidation.The TS fraction with a low degree of condensation and abundant side chains had a stronger oxidation activity and thus introduced more cross-linked oxygen-containing functional groups C(O)―O which prevented carbon layer rearrangement during the carbonization.As a result,a disordered hard carbon with more defects was formed,which improved the electrochemical performance.Therefore,the carbon materials derived from TS(O-TS-1000)had an obvious disordered structure and a larger layer spacing,giving them better sodium storage perform-ance than those derived from the TI-PS fraction(O-TI-PS-1000).The specific capacity of O-TS-1000 was about 250 mAh/g at 20 mA/g,which was 1.67 times higher than that of O-TI-PS-1000(150 mAh/g).
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金support from the National Natural Science Foundation of China(Nos.52171107,52201203)the Hebei Provincial Natural Science Foundation,China(No.E2021501026)the National Natural Science Foundation of China-Joint Fund of Iron and Steel Research(No.U1960204).
文摘The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review presents an overview of the research progress on oxidation behavior of Co-based superalloys, including oxidation kinetics, oxides morphology, the formation and spallation of oxide layers, and importantly, the synergistic effects of alloying elements on oxidation resistance—a critical area considering the complex interactions with multiple alloying elements. Additionally, this review compares the oxidation resistance of single crystal versus polycrystalline alloys. The effect of phase interface and dislocations on oxidation behavior is also discussed. While significant progress has been achieved, areas necessitating further investigation include optimizing alloy compositions for enhanced oxidation resistance and understanding the long-term stability of oxide layers. The future prospects for Co-based superalloys are promising as ongoing research aims to address the existing challenges and unlock new applications at even higher operating temperatures.
基金supported by the National Natural Science Foundation of China,Nos.82204360(to HM)and 82270411(to GW)National Science and Technology Innovation 2030 Major Program,No.2021ZD0200900(to YL)。
文摘Traumatic brain injury involves complex pathophysiological mechanisms,among which oxidative stress significantly contributes to the occurrence of secondary injury.In this study,we evaluated hypidone hydrochloride(YL-0919),a self-developed antidepressant with selective sigma-1 receptor agonist properties,and its associated mechanisms and targets in traumatic brain injury.Behavioral experiments to assess functional deficits were followed by assessment of neuronal damage through histological analyses and examination of blood-brain barrier permeability and brain edema.Next,we investigated the antioxidative effects of YL-0919 by assessing the levels of traditional markers of oxidative stress in vivo in mice and in vitro in HT22 cells.Finally,the targeted action of YL-0919 was verified by employing a sigma-1 receptor antagonist(BD-1047).Our findings demonstrated that YL-0919 markedly improved deficits in motor function and spatial cognition on day 3 post traumatic brain injury,while also decreasing neuronal mortality and reversing blood-brain barrier disruption and brain edema.Furthermore,YL-0919 effectively combated oxidative stress both in vivo and in vitro.The protective effects of YL-0919 were partially inhibited by BD-1047.These results indicated that YL-0919 relieved impairments in motor and spatial cognition by restraining oxidative stress,a neuroprotective effect that was partially reversed by the sigma-1 receptor antagonist BD-1047.YL-0919 may have potential as a new treatment for traumatic brain injury.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.22475132 and 52101259)the Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20210324105008022)financially supported by the Shenzhen Science and Technology Innovation Program(Nos.KQTD20190929173914967 and ZDSYS20220527171401003).
文摘Engineering nanomaterials at single-atomic sites could enable unprecedented catalytic properties for broad applications,yet it remains challenging to do so on the surface of multimetallic nanocrystals.Herein,we present the multifactorial engineering(size,shape,phase,and composition)of the fully ordered PtBi nanoplates at atomic level,achieving a unique catalyst surface where the face-centered cubic(fcc)Pt edges are modified by the isolated Pd atoms and BiO_(x)adatoms.This Pd_(1)/Pt-BiO_(x)electrocatalyst exhibits an ultrahigh mass activity of 16.01 A mg^(-1)Pt+Pd toward ethanol oxidation in alkaline electrolyte and enables a direct ethanol fuel cell of peak power density of 56.7 mW cm^(−2).The surrounding BiO_(x)adatoms are critical for mitigating CO-poisoning on the Pt surface,and the Pd_(1)/Pt single-atom alloy further facilitates the electrooxidation of CH_(3)CH_(2)OH.This work offers new insights into the rational design and construction of sophisticated catalyst surface at single-atomic sites for highly efficient electrocatalysis.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030006).
文摘Magnesium matrix composites with both high strength and ductility have been achieved by introducing pure Ti particles.However,the properties of the surfaces of the composites need to be improved by surface technology,such as micro-arc oxidation(MAO).In this study,we investigated the influence of the Ti-reinforcement phase on coating growth and evolution by subjecting both AZ91 alloy and AZ91/Ti composite to MAO treatment using silicate-based and phosphate-based electrolytes.Results revealed that the Ti-reinforcement phase influenced the MAO process,altering discharge behavior,and leading to a decreased cell voltage.The vigorous discharge of the Ti-reinforcement phase induced the formation of coating discharge channels,concurrently dissolving and oxidizing Ti-reinforcement to produce a composite ceramic coating with TiO2.The MAO coating on the AZ91/Ti composite exhibited a dark blue macromorphology and distinctive local micromorphological anomalies.In silicate electrolyte,a“volcano-like”localized morphology centered on the discharge channel emerged.In contrast,treatment in phosphate-based electrolyte resulted in a coating morphology similar to typical porous ceramic coatings,with visible radial discharge micropores at the reinforcement phase location.Compared to the AZ91 alloy,the coating on the AZ91/Ti composite exhibited lower thickness and higher porosity.MAO treatment reduced the self-corrosion current density of the AZ91/Ti surface by two orders of magnitude.The silicate coating demonstrated better corrosion resistance than the phosphate coating,attributed to its lower porosity.The formation mechanism of MAO coatings on AZ91/Ti composites in phosphate-based and silicate-based electrolytes was proposed.
基金supported by the National Natural Science Foundation of China(No.52001034)the China Postdoctoral Science Foundation(No.2023M731677)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_3032).
文摘Nano-zinc oxides(ZnO)demonstrate remarkable antibacterial properties.To further enhance the corrosion resistance and antibacterial efficiency of magnesium alloy micro-arc oxidation(MAO)coatings,this study investigates the preparation of ZnO-containing micro-arc oxidation coatings with dual functionality by incorporating nano-ZnO into MAO electrolyte.The influence of varying ZnO concentrations on the microstructure,corrosion resistance,and antibacterial properties of the coating was examined through microstructure analysis,immersion tests,electrochemical experiments,and antibacterial assays.The findings revealed that the addition of nano-ZnO significantly enhanced the corrosion resistance of the MAO-coated alloy.Specifically,when the ZnO concentration in the electrolyte was 5 g/L,the corrosion rate was more than ten times lower compared to the MAO coatings without ZnO.Moreover,the antibacterial efficacy of ZnO+MAO coating,prepared with a ZnO concentration of 5 g/L,surpassed 95%after 24 h of co-culturing with Staphylococcus aureus(S.aureus).The nano-ZnO+MAO-coated alloy exhibited exceptional degradation resistance,corrosion resistance,and antibacterial effectiveness.
基金financial supports from Shanxi Provincial Natural Science Foundation,China(No.20210302123162)Shanxi Scholarship Council of China(No.2024-057)+2 种基金State Key Laboratory of Advanced Metal Materials,China(No.2019-ZD02)Science and Technology Achievement Transformation and Cultivation Project of Shanxi,China(No.2020CG011)Shanxi“1331 Project”Quality Improvement and Efficiency Project,China。
文摘A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding,consisting of outermost Cr layer and CoNiCrAlTaY transition layer.The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K.The top Cr_(2)O_(3)film and spinel oxides(i.e.,NiCr_(2)O_(4)and CoCr_(2)O_(4))exhibited a protective effect with a low oxidation reaction rate.Interfacial analysis identified Ta precipitates(Cr_(2)Ta and TaAl_(3))and Ta oxides(Ta_(2)O_(5)and Ta_(2)O_(3)),which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol(8HQ)molecules and the porous MgO layer formed via plasma electrolytic oxidation(PEO).The AZ31 Mg alloy,initially coated with a PEO layer,underwent a dipping treatment in an ethanolic solution of 0.05 M 8HQ at 50℃ for 3 h.The results were compared with those from a different procedure where the PEO layer was subjected to a hydration reaction for 2 h at 90℃ before immersion in the 8HQ solution under the same conditions.The hydration treatment played a crucial role by converting MgO to Mg(OH)_(2),significantly enhancing the surface reactivity.This transformation introduced hydroxyl groups(−OH)on the surface,which facilitated donor-acceptor interactions with the electron-accepting sites on 8HQ molecules.The calculated binding energy(Ebinding)from DFT indicated that the interaction energy of 8HQ with Mg(OH)_(2) was lower compared to 8HQ with MgO,suggesting easier adsorption of 8HQ molecules on the hydrated surface.This,combined with the increased number of active sites and enhanced surface area,allowed for extensive surface coverage by 8HQ,leading to the formation of a stable,flake-like protective layer that sealed the majority of pores on the PEO layer.DFT calculations further suggested that the hydration treatment provided multiple active sites,enabling effective contact with 8HQ and rapid electron transfer,creating ideal conditions for charge-transfer-induced physical and chemical bonding.This study shows that hydration and 8HQ treatments significantly enhance the corrosion resistance of Mg alloys,highlighting their potential for advanced anticorrosive coatings.
基金supported by the National Natural Science Foundation of China(Nos.U21B2053,52071114,52001100,and 523B2010)Outstanding Youth Project of Natural Science Foundation of Heilongjiang Province(No.YQ2023E008)+1 种基金Young Elite Scientists Sponsorship Program by CAST(NO.2021QNRC001)Heilongjiang Touyan Team Program.
文摘Silicide coatings have proven to be promising for improving the high-temperature oxidation resistance of niobium alloy.However,the long-term protective property of single silicide coating remains a long-time endeavor due to the deficiency of oxygen-consuming phases,as well as the self-healing ability of the protective layer.Herein,a silicide-based composite coating is constructed on niobium alloy by incor-poration of nano-SiC particles for enhancing the high-temperature oxidation resistance.Isothermal oxi-dation results at 1250℃ for 50 h indicate that NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multilayer coated sample with a low mass gain of 2.49 mg/cm^(2) shows an improved oxidation resistance compared with NbSi_(2) coating(6.49 mg/cm^(2)).The enhanced high-temperature antioxidant performance of NbSi_(2)/Nb_(2)O_(5)-SiO_(2)/SiC multi-layer coating is mainly attributed to the formation of the protective SiO_(2) self-healing film and the high-temperature diffusion behavior of NbSi_(2)/substrate.
