Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications,including fuel cells,chemical conversion,and batteries.Nanocatalysts demon...Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications,including fuel cells,chemical conversion,and batteries.Nanocatalysts demonstrate high activity by expanding the number of active sites,but they also intensify deactivation issues,such as agglomeration and poisoning,simultaneously.Exsolution for bottomup synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional nanomaterials.Nanoparticles are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction process.Their uniformity and stability,resulting from the socketed structure,play a crucial role in the development of novel nanocatalysts.Recently,tremendous research efforts have been dedicated to further controlling exsolution particles.To effectively address exsolution at a more precise level,understanding the underlying mechanism is essential.This review presents a comprehensive overview of the exsolution mechanism,with a focus on its driving force,processes,properties,and synergetic strategies,as well as new pathways for optimizing nanocatalysts in diverse applications.展开更多
In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclu...In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclusion. Microscopic, TEM and energy spectral observa-tions and studies confirmed that these lamellae are phlogopite. They are colourless and acicularin section, generally 0.5-5μm in width and 10-100μm in length. Nevertheless, fine lamellae,0.05-0.1μm wide and 1-2μm long, are also well developed. Along [111] of the garnet, three setsof phlogopite lamellae show oriented arrangement approximately at angles of 60°-70°, indi-cating that these lamellae might be the product of exsolution from garnet as a result ofpressure-release when eclogite ascended from the relatively deep level to the relatively shallowlevel of the mantle. Tiny acicular exsolution minerals (or inclusions) are commonly found ingarnet and pyroxene in eclogite inclusions of kimberlites all over the world and it has been re-ported that the identified exsolution minerals include pyroxene and rutile. This is the first timethat phlogopite exsolution lamillae were found in eclogite inclusions in the world.展开更多
The effect of silver(Ag)exsolution on the electrical conductivity of strontium-doped lanthanum manganite(La1-x-ySrxAgyMnO3-δ,LSAM)and ferrite(La1-x-ySrxAgyFeO3-δ,LSAF)perovskites was investigated.The single-phase Ag...The effect of silver(Ag)exsolution on the electrical conductivity of strontium-doped lanthanum manganite(La1-x-ySrxAgyMnO3-δ,LSAM)and ferrite(La1-x-ySrxAgyFeO3-δ,LSAF)perovskites was investigated.The single-phase Ag-doped materials formed at 800℃ using modified Pechini method and revealed thermal stability in oxidizing atmosphere up to sintering temperature of the materials at 1,200℃.The exsolution of the metallic Ag nanoparticles was performed at 420-500℃ in reducing atmosphere of 5%H2/N2.Scanning electron microcopy results exhibited the metallic Ag phase nanoparticles on the surface of the oxide backbone with a good contact of Ag to the surface of the perovskite after exsolution.The electrical conductivity of the materials was investigated in the temperature range of 50-900℃ in air and isothermally in 5%H2/N2 at 420 and 500℃ by means of four probe DC measurement method,and reached 80-230 S·cm^-1 for undoped and Ag-doped LSF and LSM.The electrical conductivity results showed improving conductivity in Ag-doped single-phase and Ag nanoparticle decorated perovskites after Ag exsolution.The results revealed the dependence of electrical conductivity on the atmosphere,temperature and Ag exsolution time.展开更多
Ni nanocatalysts produced through exsolution have shown strong resistance to particle sintering and carbon coking in a beneficial dry reforming of methane(DRM)reaction utilizing greenhouse gases such as CH_(4)and CO_(...Ni nanocatalysts produced through exsolution have shown strong resistance to particle sintering and carbon coking in a beneficial dry reforming of methane(DRM)reaction utilizing greenhouse gases such as CH_(4)and CO_(2).However,most of the existing oxide supports for exsolution have been limited to perovskite oxide,while studies on fluorite support have been rarely conducted due to the limited solubility despite its excellent redox stability.Here we demonstrate that 3 mol%Ni can be successfully dissolved into the yttria-stabilized zirconia(YSZ)lattice and be further exsolved to the surface in a reducing atmosphere.The YSZ decorated with exsolved Ni nanoparticles shows enhanced catalytic activity for DRM reaction compared to the conventional cermet type of bulk Ni-YSZ.Moreover,the catalytic activity is extremely stable for about 300 h without significant degradation.Overall results suggest that the YSZ-based fluorite structure can be utilized as one of the support oxides for exsolution.展开更多
The exsolution of clinopyroxene and rutile in coarse-grain garnet is found in the gneissic K-feldspar(-bearing) garnet clinopyroxenite from Yinggelisayi in the Altyn Tagh, NW China. The maximum content of the exsolved...The exsolution of clinopyroxene and rutile in coarse-grain garnet is found in the gneissic K-feldspar(-bearing) garnet clinopyroxenite from Yinggelisayi in the Altyn Tagh, NW China. The maximum content of the exsolved clinopyroxene in the garnet is up to >5% by volume. The reconstructed precursor garnet (Grt1) before exsolution has a maximum Si content of 3.061 per formula uint, being of supersilicic or majoritic garnet. The peak-stage metamorphic pressure of >7 GPa is estimated using the geobarometer for volume percentage of exsolved pyroxene in garnet and the Si-(Al+Cr) geobarometer for majoritic garnet, and the temperature of about 1000℃ using the ternary alkali-feldspar geothermometer and the experimental data of ilmen- ite-magnetite solid solution. The protoliths of the rocks are intra-plate basic and intermediate ig- neous rocks, of which the geochemical features indicate that they are probably the products of the evolution of basic magma deriving from the continental lithosphere mantle. The rocks are in outcrops associated with ultrahigh pressure garnet-bearing lherzolite and ultrahigh pressure garnet granitoid gneiss. All of these data suggest that the ultrahigh pressure metamorphic rocks in the Altyn Tagh are the products of deep-subduction of the continental crust, and such deep- subduction probably reaches to >200 km in depth. This may provide new evidence for further discussion of the dynamic mechanism of the formation and evolvement of the Altyn Tagh and the other collision orogenic belts in western China.展开更多
The exsolution lamellae of quartz and clinoen-statite are idenfied in diopside of garnet-pyroxenolite from the North Dabie Mountain by transmission electron microscopy, which is interpreted that the lamellae are origi...The exsolution lamellae of quartz and clinoen-statite are idenfied in diopside of garnet-pyroxenolite from the North Dabie Mountain by transmission electron microscopy, which is interpreted that the lamellae are originally exsolved from a former ultra-high-pressure clinopyroxene due to decreasing of pressure. Study of petrography shows that there is compositional zoning hi the diopside itself. It is implied that the garnet-pyroxenolite had undergone intensive high-temperature granulite fades and high-amphibolitic fades retrogressive metamorphism, while the peridotite (the garnet-pyroxenolite’s host rock) emplaced the展开更多
Exsolution of rod-like ilmenite (Ilm) and Cr-Ti magnetite (Mt) have been found in olivine of garnet-wehrlite from the core of Chinese Continental Sciences Drilling (CCSD). Their composition, morphology, crystal struct...Exsolution of rod-like ilmenite (Ilm) and Cr-Ti magnetite (Mt) have been found in olivine of garnet-wehrlite from the core of Chinese Continental Sciences Drilling (CCSD). Their composition, morphology, crystal structure and their topotaxies with host olivine have been studied in detail by the transmission electron microscopy (TEM) and electron probe microanaly- sis (EPMA) technique. It shows that rod-like Ilm exsolution reported in this paper has similar characteristic with that of Alpe Arami olivine, while Cr-Ti magnetite exsolution mentioned in this paper has large discrepancy with chromite exsolution in Alpe Arami olivine. These observations suggest that both of the exsolutions found in this paper should be solid solution phases in β-olivine at their first period, then experiencing decomposition of solid solution and therefore forming Ilm and Cr-Ti magnetite exsolution with the pressure decreasing. So, this garnet-wehrlite perhaps had been ever located in mantle transition zone with a minimum depth of 300 km.展开更多
Fuel flexibility is one of the most distinguished advantages of solid oxide fuel cells(SOFCs)over other low-temperature fuel cells.Furthermore,the combination of ammonia fuel and SOFCs technology should be a promising...Fuel flexibility is one of the most distinguished advantages of solid oxide fuel cells(SOFCs)over other low-temperature fuel cells.Furthermore,the combination of ammonia fuel and SOFCs technology should be a promising clean energy system after considering the high energy density,easy transportation/storage,matured synthesis technology and carbon-free nature of NH_(3) as well as high efficiency of SOFCs.However,the large-scale applications of direct-ammonia SOFCs(DASOFCs)are strongly limited by the inferior anti-sintering capability and catalytic activity for ammonia decomposition reaction of conventional nickel-based cermet anode.Herein,a slightly ruthenium(Ru)doping in perovskite oxides is proposed to promote the alloy nanoparticle exsolution,enabling better DA-SOFCs with enhanced power outputs and operational stability.After treating Ru-doped Pr_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.75)Ru_(0.05)O_(3-δ) single-phase perovskite in a reducing atmosphere,in addition to the formation of two layered Ruddlesden-Popper perovskites and Pr_(2)O_(3) nanoparticles(the same as the Ru-free counterpart,Pr_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)),the exsolution of CoFeRu-based alloy nanoparticles is remarkably promoted.Such reduced Pr_(0.6)Sr0.4Co_(0.2)Fe_(0.75)Ru_(0.05)O_(3-δ) composite anode shows superior catalytic activity and stability for NH_(3) decomposition reaction as well as anti-sintering capability in DA-SOFCs to those of reduced Pr0.6Sr0.4Co0.2Fe0.8O_(3-δ)due to the facilitated nanoparticle exsolution and stronger nanoparticle/substrate interaction.This work provides a facile and effective strategy to design highly active and durable anodes for DA-SOFCs,promoting large-scale applications of this technology.展开更多
The rational modification of perovskite oxides(ABO3−δ)is essential to improve the efficiency and stability of oxygen electrolysis.Surface engineering represents a facile approach to modify perovskites for enhanced pe...The rational modification of perovskite oxides(ABO3−δ)is essential to improve the efficiency and stability of oxygen electrolysis.Surface engineering represents a facile approach to modify perovskites for enhanced performance.Through compositional design and in situ exsolution,a Ru-doped(La_(0.8)Sr_(0.2))_(0.9)Co_(0.1)Fe_(0.8)Ru_(0.1)O_(3−δ)(LSCFR)perovskite anchored with CoFe(Ru)alloy particles on the surface was fabricated for oxygen evolution reaction(OER)in this work.Experimental results and calculations indicate that Ru-doping promotes the exsolution of CoFe(Ru)from the perovskite parent.Upon exsolution in the reduced atmosphere for 3 h,the catalyst(LSCFR-3)exhibited superior OER performance with an overpotential of 347 mV and a Tafel slope of 54.65 mV·dec^(−1),and showed good stability in contrast to the pristine LSCFR.The exsolution of CoFe(Ru)particles,Ru doping,and the increase of surface oxygen vacancies are responsible for the enhancement of OER performance.The findings obtained in this study highlight the possibility of controlling exsolution and composition of nanoparticles by element doping and prove that in situ exsolution is an effective strategy for designing OER catalysts.展开更多
The Dashuigou Te deposit, Sichuan Province, is a unique independent one found up to date in the world. During the mineralogical study of this deposit, the authors observed a number of small vermicular, linear or lamel...The Dashuigou Te deposit, Sichuan Province, is a unique independent one found up to date in the world. During the mineralogical study of this deposit, the authors observed a number of small vermicular, linear or lamellar minerals in the tsumoite. Such a complex exsolution phenomenon is noted for the first time in Te minerals. The assemblage of tsumoite + exsolution is named complex exsolution zone. We will make detailed study on this exsolution structure and discuss its origin.展开更多
Solid oxide electrolysis cell(SOEC)is a promising technology for CO_(2) conversion and renewable energy storage with high efficiency.It is highly desirable to develop catalytically active cathodes for CO_(2) electroly...Solid oxide electrolysis cell(SOEC)is a promising technology for CO_(2) conversion and renewable energy storage with high efficiency.It is highly desirable to develop catalytically active cathodes for CO_(2) electrolysis.Herein,cathode materials with different structural stabilities are designed by Nb substitution on La_(0.5)Sr_(0.5)Fe_(0.8)Co_(0.2)O_(3-δ)(LSFC82)to obtain La_(0.5)Sr_(0.5)Fe_(0.7)Co_(0.2)Nb_(0.1)O_(3-δ)(LSFCN721)and La_(0.5)Sr_(0.5)Fe_(0.8)Co_(0.1)Nb_(0.1)O_(3-δ)(LSFCN811),respectively.LSFC82-Sm_(0.2)Ce_(0.8)O_(2-δ)(SDC)cathode with inferior structural stability(ability to maintain the structure)shows desirable CO_(2) electrolysis performance with the generated current density of 1.80 A cm^(-2)2 at 1.6 V and stable performance during 110 h operation at 1.2 V and 800℃.However,LSFC82 particles are collapsed into pieces after stability test with the generation of Co nanoparticles simultaneously.The frameworks of LSFCN721 and LSFCN811 particles maintain well because of the high-valent niobium,but Co exsolution,ox-ygen vacancy content and the corresponding CO_(2) electrolysis performance are restricted.This work confirms that Co nanoparticles can be exsolved from LSFC82-SDC cathode during CO_(2) electrolysis,providing references for constructing metallic nanoparticles decorated-perovskite cathodes for SOECs.展开更多
We made precipitated nano-ceria(~5 nm) on the surface of the catalyst by heat treatment of Cesupersaturated amorphous CeTiOxto improve the oxygen storage properties of CeO_2. The catalysts were prepared by sol-gel met...We made precipitated nano-ceria(~5 nm) on the surface of the catalyst by heat treatment of Cesupersaturated amorphous CeTiOxto improve the oxygen storage properties of CeO_2. The catalysts were prepared by sol-gel methods and TiO_2 nanoparticles were preferentially generated as a core material to form selective Ce-supersaturated structure on the catalyst surface. Reaction temperature and amount of doping element are optimized to induce selective crystallization of CeO_2. Cee Ce(2 nd shell)bond around 0.38 nm of Ce L3-edge extended X-ray absorption fine structure is reduced and nanostructure of precipitated ceria on the surface is observed by HREM. The catalyst is present as amorphous with precipitated nano-CeO_2 on the surface. The de-NOxefficiency of the catalyst, which has precipitated CeO_2, improves by ~50% owing to the simultaneous reactions of the nano CeO_2 and the amorphous CeTiO_x.展开更多
Electrochemical reduction of CO_(2)into valuable fuels and chemicals has become a contemporary research area,where the heterogeneous catalyst plays a critical role.Metal nanoparticles supported on oxides performing as...Electrochemical reduction of CO_(2)into valuable fuels and chemicals has become a contemporary research area,where the heterogeneous catalyst plays a critical role.Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation.Here,we review the CO_(2)reduction with active materials prepared by exsolution.The fundamental of exsolution was summarized in terms of mechanism and models,materials,and driven forces.The advances in the exsolved materials used in hightemperature CO_(2)electrolysis were catalogued into tailored interfaces,synergistic effects on alloy particles,phase transition,reversibility and electrochemical switching.展开更多
The Sanaga iron ore prospect is a recent discovery in the Nyong Series with a resource estimated at 82.9 Mt at 32.1%Fe and whose origin remains debatable.The mineralization occurs as NE-SW oriented discontinuous lenti...The Sanaga iron ore prospect is a recent discovery in the Nyong Series with a resource estimated at 82.9 Mt at 32.1%Fe and whose origin remains debatable.The mineralization occurs as NE-SW oriented discontinuous lenticular bodies of magnetite-bearing pyroxenegneisses(MPG)hosted by ortho-derived gneisses.Rare amphibolites are observed.The MPG mineral assemblage consists of quartz-magnetite-orthopyroxene-garnet-tremolite/actinolite exhibiting a granoblastic texture,which is characteristic of granulite facies metamorphism.The granodioritic gneisses show compositional features of the tonalite-trondhjemite-granodiorite association.Their trace and REE element geochemistry indicate their protolith melt resulted from the partial melting of a subducted oceanic slab,with interaction with the overlying mantle wedge during ascent.The amphibolites show enrichment in LILE with negative Ta–Nb and Zr–Hf indicating arc-related magmas generated by partial melting of a sub-continental lithospheric mantle source with metasomatism by subduction-related fluids.The MPG exhibits oxidation-exsolution features characterized by ilmenite lamellae,with hematite fracture-fillinginmagnetite,andlacksfeatures characteristic of typical BIF such as LREE depletion relative to HREE,positive Eu,La,and Y anomalies.Based on the results of this study,we interpret the Sanaga MPG as a possible skarn-type mineralization formed by the metamorphism/metasomatism of a possible BIF protolith.The results of this study compare with similar magnetite-rich mineralization in the Sa o Francisco craton in northeastern Brazil and enhance the correlation of pre-drift reconstructions of the Sa o Francisco–Congo Cratons.展开更多
The Beni Bousera massif(Rifean belt,northern Morocco)is predominantly composed of spinel lherzolite with subordinate garnet pyroxenite and garnet peridotite layers.It formed an antiformal dome which was overlain by gr...The Beni Bousera massif(Rifean belt,northern Morocco)is predominantly composed of spinel lherzolite with subordinate garnet pyroxenite and garnet peridotite layers.It formed an antiformal dome which was overlain by graphite-sillimanite-garnet gneisses(kinzigites)equilibrated at around 1 GPa and 750℃.Within these kinzigites,kyanite-bearing basic granulites record somewhat higher PT conditions of around 1.6-2.0 GPa and 760-820℃.Garnet clinopyroxenite(either graphite-bearing or graphi-展开更多
As a powerful tracer in high-temperature geochemistry,Fe isotopes have been studied for their behaviour during fl uid exsolution and evolution related to felsic magma system,but that for carbonatite magma system remai...As a powerful tracer in high-temperature geochemistry,Fe isotopes have been studied for their behaviour during fl uid exsolution and evolution related to felsic magma system,but that for carbonatite magma system remains unknown.Here we study the Fe isotope fractionation behaviour during fenitization–processes that widely occur associated with carbonatite or alkaline intrusions.Nine fenite/carbonatite samples from carbonatite dykes at Bayan Obo area are analyzed for their Fe isotope compositions as well as elemental compositions.Combined with previous reported carbonatite δ^(56)Fe data,the results show that carbonatites range from-0.35‰to 0.28‰,with an average of-0.10‰in δ^(56)Fe values,while fenites range from-0.17‰to 0.30‰,with an average of 0.11‰in δ^(56)Fe values.This indicates that fenitizing fl uids exsolved from carbonatite melts are enriched in heavier Fe isotopes.Such a Fe isotope fractionation trend is diff erent from that for fl uid exsolution from felsic magmatism.δ^(56)Fe values in fenites are negatively correlated with indicators of fenitization intensity such as(Na+K),Ti,Ba,Th,Nb,U or Pb abundances,likely refl ecting that Fe isotopes fractionate during the evolution of the fenitizing fl uids.Thus,Fe isotopes are a valuable tool for tracing fl uid exsolution and evolution relevant to carbonatite magmatism and related metal mineralization.展开更多
Supported Pd based catalysts are considered as the efficient candidates for low-carbon alkane oxidation for their outstanding capability to break C-H bond. Whereas, the irreversible deactivation of Pd based catalysts ...Supported Pd based catalysts are considered as the efficient candidates for low-carbon alkane oxidation for their outstanding capability to break C-H bond. Whereas, the irreversible deactivation of Pd based catalysts was still frequently observed. Herein, we reinforced the extruded Pd nanoparticles with quantitive Pt to assemble the evenly distributed Pd Pt nanoalloy onto ferrite perovskite(Pd Pt-LCF) matrix with strengthened robustness of metal/oxide support interface. We further co-achieved the enhanced performance, anti-overoxidation as well as resistance of vapor-poisoning in durability measurement. The operando X-ray photoelectron spectroscopy(O-XPS) combined with various morphology characterizations confirms that the accumulation of surface deep-oxidation species of Pd^(4+) is the culprit for fast activity loss in exsolved Pd system, especially at high temperature of 400 ℃. Conversely, it could be completely suppressed by in-situ alloying Pd with equal amount of Pt, which helps maintain the metastable Pd^(2+)/Pd shell and metallic solid-solution core structure. The density function theory(DFT) calculations further buttress that the dissociation of C–H was facilitated on alloy/perovskite interface which is, on the contrary, resistant toward O–H bond cleavage, as compared to Pd/perovskite. Our work suggests that the modification of exsolved metal/oxide catalytic interface could further enrich the toolkit of heterogeneous catalyst design.展开更多
Stable and flexible metal nanoparticles(NPs)with regeneration ability are critical for long-term operation of solid oxide electrolysis cells(SOECs).Herein,a novel perovskite electrode with stoichiometric Pr_(0.4)Sr_(0...Stable and flexible metal nanoparticles(NPs)with regeneration ability are critical for long-term operation of solid oxide electrolysis cells(SOECs).Herein,a novel perovskite electrode with stoichiometric Pr_(0.4)Sr_(0.6)Co_(0.125)Fe_(0.75)Mo_(0.125)O_(3)−δ(PSFCM)is synthesized and studied,which undergoes multiple redox cycles to validate its structural stability and NPs reversibility.The Co-Fe alloy has exsolved from the parent bulk under reducing atmosphere,and is capable of reincorporation into the parent oxide after re-oxidation treatment.During the redox process,we successfully manipulate the size and population density of the exsolved NPs,and find that the average particle size significantly reduces but the population density increases correspondingly.The electrode polarization resistance of the symmetric cell remains stable for 450 h,and even activates after the redox cycling,which may be attributed to the higher quantity and larger specific surface area of the regenerated Co-Fe alloy NPs.Moreover,the electrochemical performance towards carbon dioxide reduction reaction(CO_(2)RR)is evaluated,and the CO_(2)electrolyzer consisting of CoFe@PSCFM-Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)dual-phase electrode exhibits an excellent current density of 1.42 A·cm^(−2)at 1.6 V,which reaches 1.7 times higher than 0.83 A·cm^(−2)for the pristine PSCFM electrode.Overall,with this flexible and reversible high-performance SOEC cathode material,new options and perspectives are provided for the efficient and durable CO_(2)electrolysis.展开更多
High temperature electrochemical energy conversion and storage technologies,such as solid oxide electrochemical cells (SOCs),have emerged as promising alternatives to mitigate environmental issues associated with comb...High temperature electrochemical energy conversion and storage technologies,such as solid oxide electrochemical cells (SOCs),have emerged as promising alternatives to mitigate environmental issues associated with combustion-based technologies.There has been increased interest for nanoengineering SOC electrodes to enhance their efficiency.A major drive is the necessity for improved electrode kinetics via optimization of electrocatalysts for different key reactions in these devices.In this perspective,we discuss the requirements for SOC electrodes and nanoengineering strategies employed to achieve flexibility in electrode materials.We focus on identifying ways in which these nanoengineered materials foster advancements in the SOC electrocatalytic activity,selectivity,and stability.We conclude by proposing approaches that would lead to more stable electrocatalytic nanostructures with high degree of control over the number and nature of active sites.These nanostructures would enable systematic kinetic studies that could provide an in depth understanding of the reaction mechanisms that govern performance,leading to valuable knowledge for designing optimal electrode materials.展开更多
One of the key tasks in solid oxide fuel cell research is to develop cost-competitive electrodes that work efficiently in wide range of air and fuel utilizations.Herein,we promote our study to a series of Cobalt and T...One of the key tasks in solid oxide fuel cell research is to develop cost-competitive electrodes that work efficiently in wide range of air and fuel utilizations.Herein,we promote our study to a series of Cobalt and Titanium substituted La_(0.4)Sr_(0.6)Fe_(0.7)Ti_(0.3-x)Co_(x)O_(3-δ)(LSFTC,x=0,0.05,0.1,0.2)perovskite oxides.It is shown that Cobalt doping effectively improves the electrical conductivity and oxygen electrochemical reduction activity,yielding decreased cathode polarization resistance and lower dependence of pO_(2) change.For example,σ_(600℃)=81 S/cm and R_(p,C750℃)=0.1 Ω cm^(2) for LSFTC-5 are obtained in pO_(2)=0.21 atm.In anode conditions of wet H2,the LSFTC cubic perovskites are partially reduced to hybrid structure of ABO_(3)-A_(2)BO_(4)-metal with Cobalt doping amount less than 10% and are fully decomposed to A_(2)BO_(4)-metal with 20% doping.The higher Cobalt substitution generates more nano particles exsolution,which promotes anode processes at low temperatures.However,the generated AO-rich compositions are shown detrimental to anode performance in both conducting property and anode catalytic activity under low H_(2) partial pressures.In current study,the electrodes are evaluated under practical working conditions with broad pO_(2) and pH_(2),which provides guidelines for industrial-applicable SrFeO_(3) based symmetrical electrode development.展开更多
基金This study was supported by the National Research Foundation of Korea(NRF-2021R1C1C1010233)funded by the Korean government(MSIT)+1 种基金This research was also supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Grant(No.G032542411)funded by the Korea Ministry of Trade,Industry,and Energy(MOTIE).
文摘Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications,including fuel cells,chemical conversion,and batteries.Nanocatalysts demonstrate high activity by expanding the number of active sites,but they also intensify deactivation issues,such as agglomeration and poisoning,simultaneously.Exsolution for bottomup synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional nanomaterials.Nanoparticles are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction process.Their uniformity and stability,resulting from the socketed structure,play a crucial role in the development of novel nanocatalysts.Recently,tremendous research efforts have been dedicated to further controlling exsolution particles.To effectively address exsolution at a more precise level,understanding the underlying mechanism is essential.This review presents a comprehensive overview of the exsolution mechanism,with a focus on its driving force,processes,properties,and synergetic strategies,as well as new pathways for optimizing nanocatalysts in diverse applications.
文摘In No. 50 kimberlite pipe of Fuxian County, Liaoning Province, an eclogite inclusion(nodule), which is extremely rare in kimberlites, was discovered and phlogopite exsolutionlamellae were found in garnets of the inclusion. Microscopic, TEM and energy spectral observa-tions and studies confirmed that these lamellae are phlogopite. They are colourless and acicularin section, generally 0.5-5μm in width and 10-100μm in length. Nevertheless, fine lamellae,0.05-0.1μm wide and 1-2μm long, are also well developed. Along [111] of the garnet, three setsof phlogopite lamellae show oriented arrangement approximately at angles of 60°-70°, indi-cating that these lamellae might be the product of exsolution from garnet as a result ofpressure-release when eclogite ascended from the relatively deep level to the relatively shallowlevel of the mantle. Tiny acicular exsolution minerals (or inclusions) are commonly found ingarnet and pyroxene in eclogite inclusions of kimberlites all over the world and it has been re-ported that the identified exsolution minerals include pyroxene and rutile. This is the first timethat phlogopite exsolution lamillae were found in eclogite inclusions in the world.
文摘The effect of silver(Ag)exsolution on the electrical conductivity of strontium-doped lanthanum manganite(La1-x-ySrxAgyMnO3-δ,LSAM)and ferrite(La1-x-ySrxAgyFeO3-δ,LSAF)perovskites was investigated.The single-phase Ag-doped materials formed at 800℃ using modified Pechini method and revealed thermal stability in oxidizing atmosphere up to sintering temperature of the materials at 1,200℃.The exsolution of the metallic Ag nanoparticles was performed at 420-500℃ in reducing atmosphere of 5%H2/N2.Scanning electron microcopy results exhibited the metallic Ag phase nanoparticles on the surface of the oxide backbone with a good contact of Ag to the surface of the perovskite after exsolution.The electrical conductivity of the materials was investigated in the temperature range of 50-900℃ in air and isothermally in 5%H2/N2 at 420 and 500℃ by means of four probe DC measurement method,and reached 80-230 S·cm^-1 for undoped and Ag-doped LSF and LSM.The electrical conductivity results showed improving conductivity in Ag-doped single-phase and Ag nanoparticle decorated perovskites after Ag exsolution.The results revealed the dependence of electrical conductivity on the atmosphere,temperature and Ag exsolution time.
基金This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(No.20173020032120)This work also was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2019R1C1C1005801)Partial support from“CO2 utilization battery for hydrogen production based on fault-tolerance deep learning”(1.200097.01)is also acknowledged.
文摘Ni nanocatalysts produced through exsolution have shown strong resistance to particle sintering and carbon coking in a beneficial dry reforming of methane(DRM)reaction utilizing greenhouse gases such as CH_(4)and CO_(2).However,most of the existing oxide supports for exsolution have been limited to perovskite oxide,while studies on fluorite support have been rarely conducted due to the limited solubility despite its excellent redox stability.Here we demonstrate that 3 mol%Ni can be successfully dissolved into the yttria-stabilized zirconia(YSZ)lattice and be further exsolved to the surface in a reducing atmosphere.The YSZ decorated with exsolved Ni nanoparticles shows enhanced catalytic activity for DRM reaction compared to the conventional cermet type of bulk Ni-YSZ.Moreover,the catalytic activity is extremely stable for about 300 h without significant degradation.Overall results suggest that the YSZ-based fluorite structure can be utilized as one of the support oxides for exsolution.
基金the National Key Basic Research Program of China(Grant No. 1999075508) the National Natural Science Foundation of China(Grant Nos.40372088,49972063 , 140032010-c)+1 种基金the Cadreman Teacher Foundation of the Ministry of Education of China (Grant No. 40133020) the Open Foundation of the Laboratory of Orogen and Basin of the Ministry of Education of Peking University.
文摘The exsolution of clinopyroxene and rutile in coarse-grain garnet is found in the gneissic K-feldspar(-bearing) garnet clinopyroxenite from Yinggelisayi in the Altyn Tagh, NW China. The maximum content of the exsolved clinopyroxene in the garnet is up to >5% by volume. The reconstructed precursor garnet (Grt1) before exsolution has a maximum Si content of 3.061 per formula uint, being of supersilicic or majoritic garnet. The peak-stage metamorphic pressure of >7 GPa is estimated using the geobarometer for volume percentage of exsolved pyroxene in garnet and the Si-(Al+Cr) geobarometer for majoritic garnet, and the temperature of about 1000℃ using the ternary alkali-feldspar geothermometer and the experimental data of ilmen- ite-magnetite solid solution. The protoliths of the rocks are intra-plate basic and intermediate ig- neous rocks, of which the geochemical features indicate that they are probably the products of the evolution of basic magma deriving from the continental lithosphere mantle. The rocks are in outcrops associated with ultrahigh pressure garnet-bearing lherzolite and ultrahigh pressure garnet granitoid gneiss. All of these data suggest that the ultrahigh pressure metamorphic rocks in the Altyn Tagh are the products of deep-subduction of the continental crust, and such deep- subduction probably reaches to >200 km in depth. This may provide new evidence for further discussion of the dynamic mechanism of the formation and evolvement of the Altyn Tagh and the other collision orogenic belts in western China.
基金the Ministry of Science and Technology of China (Grant No. G1999075501) the National Natural Science Foundation of China (Grant No. 49794041) the Postdoctor Science Foundation of China, the State Key Laboratory of Mineral Deposit, University of Nanji
文摘The exsolution lamellae of quartz and clinoen-statite are idenfied in diopside of garnet-pyroxenolite from the North Dabie Mountain by transmission electron microscopy, which is interpreted that the lamellae are originally exsolved from a former ultra-high-pressure clinopyroxene due to decreasing of pressure. Study of petrography shows that there is compositional zoning hi the diopside itself. It is implied that the garnet-pyroxenolite had undergone intensive high-temperature granulite fades and high-amphibolitic fades retrogressive metamorphism, while the peridotite (the garnet-pyroxenolite’s host rock) emplaced the
基金supported by MST(Grant No.2003CD716506)NSFC(Grant No.40372026).
文摘Exsolution of rod-like ilmenite (Ilm) and Cr-Ti magnetite (Mt) have been found in olivine of garnet-wehrlite from the core of Chinese Continental Sciences Drilling (CCSD). Their composition, morphology, crystal structure and their topotaxies with host olivine have been studied in detail by the transmission electron microscopy (TEM) and electron probe microanaly- sis (EPMA) technique. It shows that rod-like Ilm exsolution reported in this paper has similar characteristic with that of Alpe Arami olivine, while Cr-Ti magnetite exsolution mentioned in this paper has large discrepancy with chromite exsolution in Alpe Arami olivine. These observations suggest that both of the exsolutions found in this paper should be solid solution phases in β-olivine at their first period, then experiencing decomposition of solid solution and therefore forming Ilm and Cr-Ti magnetite exsolution with the pressure decreasing. So, this garnet-wehrlite perhaps had been ever located in mantle transition zone with a minimum depth of 300 km.
基金financially supported by the National Natural Science Foundation of China(Nos.22108121,21908106 and21878158)Jiangsu Natural Science Foundation(No.BK20190682)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Fuel flexibility is one of the most distinguished advantages of solid oxide fuel cells(SOFCs)over other low-temperature fuel cells.Furthermore,the combination of ammonia fuel and SOFCs technology should be a promising clean energy system after considering the high energy density,easy transportation/storage,matured synthesis technology and carbon-free nature of NH_(3) as well as high efficiency of SOFCs.However,the large-scale applications of direct-ammonia SOFCs(DASOFCs)are strongly limited by the inferior anti-sintering capability and catalytic activity for ammonia decomposition reaction of conventional nickel-based cermet anode.Herein,a slightly ruthenium(Ru)doping in perovskite oxides is proposed to promote the alloy nanoparticle exsolution,enabling better DA-SOFCs with enhanced power outputs and operational stability.After treating Ru-doped Pr_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.75)Ru_(0.05)O_(3-δ) single-phase perovskite in a reducing atmosphere,in addition to the formation of two layered Ruddlesden-Popper perovskites and Pr_(2)O_(3) nanoparticles(the same as the Ru-free counterpart,Pr_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)),the exsolution of CoFeRu-based alloy nanoparticles is remarkably promoted.Such reduced Pr_(0.6)Sr0.4Co_(0.2)Fe_(0.75)Ru_(0.05)O_(3-δ) composite anode shows superior catalytic activity and stability for NH_(3) decomposition reaction as well as anti-sintering capability in DA-SOFCs to those of reduced Pr0.6Sr0.4Co0.2Fe0.8O_(3-δ)due to the facilitated nanoparticle exsolution and stronger nanoparticle/substrate interaction.This work provides a facile and effective strategy to design highly active and durable anodes for DA-SOFCs,promoting large-scale applications of this technology.
基金the National Natural Science Foundation of China(No.51901161)Natural Science Foundation of Guangdong Province(No.2021A1515011955)+2 种基金College Innovation Team Project of Guangdong Province(No.2021KCXTD042)Major Projects of Guangdong Education Department for Foundation Research and Applied Research(No.2020ZDZX2063)Wuyi University-Hong Kong-Macao Joint Research and Development Fund(No.2019WGALH06).
文摘The rational modification of perovskite oxides(ABO3−δ)is essential to improve the efficiency and stability of oxygen electrolysis.Surface engineering represents a facile approach to modify perovskites for enhanced performance.Through compositional design and in situ exsolution,a Ru-doped(La_(0.8)Sr_(0.2))_(0.9)Co_(0.1)Fe_(0.8)Ru_(0.1)O_(3−δ)(LSCFR)perovskite anchored with CoFe(Ru)alloy particles on the surface was fabricated for oxygen evolution reaction(OER)in this work.Experimental results and calculations indicate that Ru-doping promotes the exsolution of CoFe(Ru)from the perovskite parent.Upon exsolution in the reduced atmosphere for 3 h,the catalyst(LSCFR-3)exhibited superior OER performance with an overpotential of 347 mV and a Tafel slope of 54.65 mV·dec^(−1),and showed good stability in contrast to the pristine LSCFR.The exsolution of CoFe(Ru)particles,Ru doping,and the increase of surface oxygen vacancies are responsible for the enhancement of OER performance.The findings obtained in this study highlight the possibility of controlling exsolution and composition of nanoparticles by element doping and prove that in situ exsolution is an effective strategy for designing OER catalysts.
基金Doctoral Program of State Education Commission of Chinathe State Key Laboratory of Mineralization, Nanjing University
文摘The Dashuigou Te deposit, Sichuan Province, is a unique independent one found up to date in the world. During the mineralogical study of this deposit, the authors observed a number of small vermicular, linear or lamellar minerals in the tsumoite. Such a complex exsolution phenomenon is noted for the first time in Te minerals. The assemblage of tsumoite + exsolution is named complex exsolution zone. We will make detailed study on this exsolution structure and discuss its origin.
基金We gratefully acknowledge financial support from the National Key R&D Program of China(Grant 2017YFA0700102)the National Natural Science Foundation of China(Grants 92045302 and 22072146)+1 种基金the DNL Cooperation Fund,CAS(DNL201923)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant XDB17020200).
文摘Solid oxide electrolysis cell(SOEC)is a promising technology for CO_(2) conversion and renewable energy storage with high efficiency.It is highly desirable to develop catalytically active cathodes for CO_(2) electrolysis.Herein,cathode materials with different structural stabilities are designed by Nb substitution on La_(0.5)Sr_(0.5)Fe_(0.8)Co_(0.2)O_(3-δ)(LSFC82)to obtain La_(0.5)Sr_(0.5)Fe_(0.7)Co_(0.2)Nb_(0.1)O_(3-δ)(LSFCN721)and La_(0.5)Sr_(0.5)Fe_(0.8)Co_(0.1)Nb_(0.1)O_(3-δ)(LSFCN811),respectively.LSFC82-Sm_(0.2)Ce_(0.8)O_(2-δ)(SDC)cathode with inferior structural stability(ability to maintain the structure)shows desirable CO_(2) electrolysis performance with the generated current density of 1.80 A cm^(-2)2 at 1.6 V and stable performance during 110 h operation at 1.2 V and 800℃.However,LSFC82 particles are collapsed into pieces after stability test with the generation of Co nanoparticles simultaneously.The frameworks of LSFCN721 and LSFCN811 particles maintain well because of the high-valent niobium,but Co exsolution,ox-ygen vacancy content and the corresponding CO_(2) electrolysis performance are restricted.This work confirms that Co nanoparticles can be exsolved from LSFC82-SDC cathode during CO_(2) electrolysis,providing references for constructing metallic nanoparticles decorated-perovskite cathodes for SOECs.
基金Project supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)through GCRC-SOP(2011-0030013)
文摘We made precipitated nano-ceria(~5 nm) on the surface of the catalyst by heat treatment of Cesupersaturated amorphous CeTiOxto improve the oxygen storage properties of CeO_2. The catalysts were prepared by sol-gel methods and TiO_2 nanoparticles were preferentially generated as a core material to form selective Ce-supersaturated structure on the catalyst surface. Reaction temperature and amount of doping element are optimized to induce selective crystallization of CeO_2. Cee Ce(2 nd shell)bond around 0.38 nm of Ce L3-edge extended X-ray absorption fine structure is reduced and nanostructure of precipitated ceria on the surface is observed by HREM. The catalyst is present as amorphous with precipitated nano-CeO_2 on the surface. The de-NOxefficiency of the catalyst, which has precipitated CeO_2, improves by ~50% owing to the simultaneous reactions of the nano CeO_2 and the amorphous CeTiO_x.
基金This work is supported by the National Key Research and Development Program of China(No.2021YFA0718900)the National Natural Science Foundation of China(No.NSCF52102137)+1 种基金We also appreciate the support from Tsinghua University Initiative Scientific Research Program and Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2022006EPSRC)the Institute for Guo Qiang,Tsinghua University(2020GQG1003).
文摘Electrochemical reduction of CO_(2)into valuable fuels and chemicals has become a contemporary research area,where the heterogeneous catalyst plays a critical role.Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation.Here,we review the CO_(2)reduction with active materials prepared by exsolution.The fundamental of exsolution was summarized in terms of mechanism and models,materials,and driven forces.The advances in the exsolved materials used in hightemperature CO_(2)electrolysis were catalogued into tailored interfaces,synergistic effects on alloy particles,phase transition,reversibility and electrochemical switching.
文摘The Sanaga iron ore prospect is a recent discovery in the Nyong Series with a resource estimated at 82.9 Mt at 32.1%Fe and whose origin remains debatable.The mineralization occurs as NE-SW oriented discontinuous lenticular bodies of magnetite-bearing pyroxenegneisses(MPG)hosted by ortho-derived gneisses.Rare amphibolites are observed.The MPG mineral assemblage consists of quartz-magnetite-orthopyroxene-garnet-tremolite/actinolite exhibiting a granoblastic texture,which is characteristic of granulite facies metamorphism.The granodioritic gneisses show compositional features of the tonalite-trondhjemite-granodiorite association.Their trace and REE element geochemistry indicate their protolith melt resulted from the partial melting of a subducted oceanic slab,with interaction with the overlying mantle wedge during ascent.The amphibolites show enrichment in LILE with negative Ta–Nb and Zr–Hf indicating arc-related magmas generated by partial melting of a sub-continental lithospheric mantle source with metasomatism by subduction-related fluids.The MPG exhibits oxidation-exsolution features characterized by ilmenite lamellae,with hematite fracture-fillinginmagnetite,andlacksfeatures characteristic of typical BIF such as LREE depletion relative to HREE,positive Eu,La,and Y anomalies.Based on the results of this study,we interpret the Sanaga MPG as a possible skarn-type mineralization formed by the metamorphism/metasomatism of a possible BIF protolith.The results of this study compare with similar magnetite-rich mineralization in the Sa o Francisco craton in northeastern Brazil and enhance the correlation of pre-drift reconstructions of the Sa o Francisco–Congo Cratons.
文摘The Beni Bousera massif(Rifean belt,northern Morocco)is predominantly composed of spinel lherzolite with subordinate garnet pyroxenite and garnet peridotite layers.It formed an antiformal dome which was overlain by graphite-sillimanite-garnet gneisses(kinzigites)equilibrated at around 1 GPa and 750℃.Within these kinzigites,kyanite-bearing basic granulites record somewhat higher PT conditions of around 1.6-2.0 GPa and 760-820℃.Garnet clinopyroxenite(either graphite-bearing or graphi-
基金the National Key R&D Programmes of China(Nos.2019YFA0708604 and 2019YFA0708404)the National Natural Science Foundation of China(No.41773018)the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources(No.J1901-29)。
文摘As a powerful tracer in high-temperature geochemistry,Fe isotopes have been studied for their behaviour during fl uid exsolution and evolution related to felsic magma system,but that for carbonatite magma system remains unknown.Here we study the Fe isotope fractionation behaviour during fenitization–processes that widely occur associated with carbonatite or alkaline intrusions.Nine fenite/carbonatite samples from carbonatite dykes at Bayan Obo area are analyzed for their Fe isotope compositions as well as elemental compositions.Combined with previous reported carbonatite δ^(56)Fe data,the results show that carbonatites range from-0.35‰to 0.28‰,with an average of-0.10‰in δ^(56)Fe values,while fenites range from-0.17‰to 0.30‰,with an average of 0.11‰in δ^(56)Fe values.This indicates that fenitizing fl uids exsolved from carbonatite melts are enriched in heavier Fe isotopes.Such a Fe isotope fractionation trend is diff erent from that for fl uid exsolution from felsic magmatism.δ^(56)Fe values in fenites are negatively correlated with indicators of fenitization intensity such as(Na+K),Ti,Ba,Th,Nb,U or Pb abundances,likely refl ecting that Fe isotopes fractionate during the evolution of the fenitizing fl uids.Thus,Fe isotopes are a valuable tool for tracing fl uid exsolution and evolution relevant to carbonatite magmatism and related metal mineralization.
基金supported by the National Natural Science Foundation of China (Nos.22272136, 22202041, 22102135, 22202163,22172129)the Fundamental Research Funds for the Central Universities (No.20720220119)+3 种基金Science and Technology Project of Fujian Province (No.2022L3077)the financial support from Guangdong Basic and Applied Basic Research Fund (No.2022A1515110239)the funds from Science and Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM)(No.HRTP-[2022]-3)the Fundamental Research Funds for the Central Universities (No.20720220008)。
文摘Supported Pd based catalysts are considered as the efficient candidates for low-carbon alkane oxidation for their outstanding capability to break C-H bond. Whereas, the irreversible deactivation of Pd based catalysts was still frequently observed. Herein, we reinforced the extruded Pd nanoparticles with quantitive Pt to assemble the evenly distributed Pd Pt nanoalloy onto ferrite perovskite(Pd Pt-LCF) matrix with strengthened robustness of metal/oxide support interface. We further co-achieved the enhanced performance, anti-overoxidation as well as resistance of vapor-poisoning in durability measurement. The operando X-ray photoelectron spectroscopy(O-XPS) combined with various morphology characterizations confirms that the accumulation of surface deep-oxidation species of Pd^(4+) is the culprit for fast activity loss in exsolved Pd system, especially at high temperature of 400 ℃. Conversely, it could be completely suppressed by in-situ alloying Pd with equal amount of Pt, which helps maintain the metastable Pd^(2+)/Pd shell and metallic solid-solution core structure. The density function theory(DFT) calculations further buttress that the dissociation of C–H was facilitated on alloy/perovskite interface which is, on the contrary, resistant toward O–H bond cleavage, as compared to Pd/perovskite. Our work suggests that the modification of exsolved metal/oxide catalytic interface could further enrich the toolkit of heterogeneous catalyst design.
基金supported by the National Natural Science Foundation of China(No.U21A20317)the National Key Research and Development Program of China(No.2022YFA1504701)+2 种基金the Fundamental Research Funds for the Central Universities(No.2042022gf0002)the start-up research funds from Wuhan Institute of Technology(No.K202201)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515010429).
文摘Stable and flexible metal nanoparticles(NPs)with regeneration ability are critical for long-term operation of solid oxide electrolysis cells(SOECs).Herein,a novel perovskite electrode with stoichiometric Pr_(0.4)Sr_(0.6)Co_(0.125)Fe_(0.75)Mo_(0.125)O_(3)−δ(PSFCM)is synthesized and studied,which undergoes multiple redox cycles to validate its structural stability and NPs reversibility.The Co-Fe alloy has exsolved from the parent bulk under reducing atmosphere,and is capable of reincorporation into the parent oxide after re-oxidation treatment.During the redox process,we successfully manipulate the size and population density of the exsolved NPs,and find that the average particle size significantly reduces but the population density increases correspondingly.The electrode polarization resistance of the symmetric cell remains stable for 450 h,and even activates after the redox cycling,which may be attributed to the higher quantity and larger specific surface area of the regenerated Co-Fe alloy NPs.Moreover,the electrochemical performance towards carbon dioxide reduction reaction(CO_(2)RR)is evaluated,and the CO_(2)electrolyzer consisting of CoFe@PSCFM-Ce_(0.8)Sm_(0.2)O_(1.9)(SDC)dual-phase electrode exhibits an excellent current density of 1.42 A·cm^(−2)at 1.6 V,which reaches 1.7 times higher than 0.83 A·cm^(−2)for the pristine PSCFM electrode.Overall,with this flexible and reversible high-performance SOEC cathode material,new options and perspectives are provided for the efficient and durable CO_(2)electrolysis.
基金We thank the financial support from the National Science Foundation(CBET-CAREER 1350623)The authors also thank the Lumigen Instrument Center at Wayne State University for the use of the X-ray diffraction(National Science Foundation MRI-1427926)electron microscopy facil让ies(National Science Foundation MRI-0216084).
文摘High temperature electrochemical energy conversion and storage technologies,such as solid oxide electrochemical cells (SOCs),have emerged as promising alternatives to mitigate environmental issues associated with combustion-based technologies.There has been increased interest for nanoengineering SOC electrodes to enhance their efficiency.A major drive is the necessity for improved electrode kinetics via optimization of electrocatalysts for different key reactions in these devices.In this perspective,we discuss the requirements for SOC electrodes and nanoengineering strategies employed to achieve flexibility in electrode materials.We focus on identifying ways in which these nanoengineered materials foster advancements in the SOC electrocatalytic activity,selectivity,and stability.We conclude by proposing approaches that would lead to more stable electrocatalytic nanostructures with high degree of control over the number and nature of active sites.These nanostructures would enable systematic kinetic studies that could provide an in depth understanding of the reaction mechanisms that govern performance,leading to valuable knowledge for designing optimal electrode materials.
基金the financial support from National Natural Science Foundation of China(51702163)Ministry of Science and Technology of China(2018YFB1502203)+1 种基金Jiangsu Province(BK20170847,BE2017098)Top-notch Academic Programs Project of Jiangsu Higher Education Institutions.
文摘One of the key tasks in solid oxide fuel cell research is to develop cost-competitive electrodes that work efficiently in wide range of air and fuel utilizations.Herein,we promote our study to a series of Cobalt and Titanium substituted La_(0.4)Sr_(0.6)Fe_(0.7)Ti_(0.3-x)Co_(x)O_(3-δ)(LSFTC,x=0,0.05,0.1,0.2)perovskite oxides.It is shown that Cobalt doping effectively improves the electrical conductivity and oxygen electrochemical reduction activity,yielding decreased cathode polarization resistance and lower dependence of pO_(2) change.For example,σ_(600℃)=81 S/cm and R_(p,C750℃)=0.1 Ω cm^(2) for LSFTC-5 are obtained in pO_(2)=0.21 atm.In anode conditions of wet H2,the LSFTC cubic perovskites are partially reduced to hybrid structure of ABO_(3)-A_(2)BO_(4)-metal with Cobalt doping amount less than 10% and are fully decomposed to A_(2)BO_(4)-metal with 20% doping.The higher Cobalt substitution generates more nano particles exsolution,which promotes anode processes at low temperatures.However,the generated AO-rich compositions are shown detrimental to anode performance in both conducting property and anode catalytic activity under low H_(2) partial pressures.In current study,the electrodes are evaluated under practical working conditions with broad pO_(2) and pH_(2),which provides guidelines for industrial-applicable SrFeO_(3) based symmetrical electrode development.