Preparation and Characterization of a Perovskite-type Mixed Conducting SrFe0.6Cu0.3Ti0.1O3-δ Membrane for Partial Oxidation of Methane to Syngas

Dense membrane with the composition of SrFe0.6Cu0.3Ti0.1O3-δ （SFCTO） was prepared by solid state reaction method. Oxygen permeation flux through this membrane was investigated at operating temperature ranging from 750℃ to 950℃ and different oxygen partial pressure. XRD measurements indicated that the compound was able to form single-phased perovskite structure in which part of Fe was replaced by Cu and Ti. The oxygen desorption and the reducibility of SFCTO powder were characterized by thermogravimetric analysis and temperature programmed reduction analysis, respectively. It was found that SFCTO had good structure stability under low oxygen pressure at high temperature. The addition of Ti increased the reduction temperature of Cu and Fe. Performance tests showed that the oxygen permeation flux through a 1.5 mm thick SFCTO membrane was 0.35-0.96 ml·min ^-1·cm^-2 under air/helium oxygen partial pressure gradient with activation energy of 53.2 kJ·mol^-1. The methane conversion of 85%, CO selectivity of 90% and comparatively higher oxygen permeation flux of 5 ml·min^-1·cm^- 2 were achieved at 850℃, when a SFCTO membrane reactor loaded with Ni-Ce/Al2O3 catalyst was applied for the partial oxidation of methane to syngas.

Electrifying Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) for focalized heating in oxygen transport membranes

Industry decarbonization requires the development of highly efficient and flexible technologies relying on renewable energy resources,especially biomass and solar/wind electricity.In the case of pure oxygen production,oxygen transport membranes(OTMs)appear as an alternative technology for the cryogenic distillation of air,the industrially-established process of producing oxygen.Moreover,OTMs could provide oxygen from different sources(air,water,CO_(2),etc.),and they are more flexible in adapting to current processes,producing oxygen at 700^(-1)000℃.Furthermore,OTMs can be integrated into catalytic membrane reactors,providing new pathways for different processes.The first part of this study was focused on electrification on a traditional OTM material(Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)),imposing different electric currents/voltages along a capillary membrane.Thanks to the emerging Joule effect,the membrane-surface temperature and the associated O_(2) permeation flux could be adjusted.Here,the OTM is electrically and locally heated and reaches 900℃on the surface,whereas the surrounding of the membrane was maintained at 650℃.The O_(2)permeation flux reached for the electrified membranes was~3.7 NmL min^(-1)cm^(-2),corresponding to the flux obtained with an OTM non-electrified at 900℃.The influence of depositing a porous Ce_(0.8)Tb_(0.2)O_(2-δ) catalytic/protective layer on the outer membrane surface revealed that lower surface temperatures(830℃)were detected at the same imposed electric power.Finally,the electrification concept was demonstrated in a catalytic membrane reactor(CMR)where the oxidative dehydrogenation of ethane(ODHE)was carried out.ODHE reaction is very sensitive to temperature,and here,we demonstrate an improvement of the ethylene yield by reaching moderate temperatures in the reaction chamber while the O_(2) injection into the reaction can be easily fine-tuned.

Enhanced H_(2) permeation and CO_(2) tolerance of self-assembled ceramic-metal-ceramic BZCYYb-Ni-CeO_(2) hybrid membrane for hydrogen separation

Perovskite-type mixed protonic-electronic conducting membranes have attracted attention because of their ability to separate and purify hydrogen from a mixture of gases generated by industrial-scale steam reforming based on an ion diffusion mechanism.Exploring cost-effective membrane materials that can achieve both high H_(2) permeability and strong CO_(2)-tolerant chemical stability has been a major challenge for industrial applications.Herein,we constructed a triple phase(ceramic-metal-ceramic)membrane composed of a perovskite ceramic phase BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)(BZCYYb),Ni metal phase and a fluorite ceramic phase CeO_(2).Under H_(2) atmosphere,Ni metal in-situ exsolved from the oxide grains,and decorated the grain surface and boundary,thus the electronic conductivity and hydrogen separation performance can be promoted.The BZCYYbNi-CeO_(2)hybrid membrane achieved an exceptional hydrogen separation performance of 0.53 mL min^(-1)cm^(-2) at 800℃ under a 10 vol% H_(2) atmosphere,surpassing all other perovskite membranes reported to date.Furthermore,the CeO_(2) phase incorporated into the BZCYYb-Ni effectively improved the CO_(2)-tolerant chemical stability.The BZCYYbNi-CeO_(2) membrane exhibited outstanding long-term stability for at least 80 h at 700℃ under 10 vol%CO_(2)-10 vol%H_(2).The success of hybrid membrane construction creates a new direction for simultaneously improving their hydrogen separation performance and CO_(2) resistance stability.

Non-associative learning behavior in mixed proton and electron conductor hybrid pseudo-diode

With inherent ionic priorities, mixed ion and electron conductor hybrid devices have been proposed for brain-inspired neuromorphic system applications, demonstrating interesting neuromorphic functions. Here, mixed proton and electron conductor (MPEC) hybrid oxide neuromorphic transistor is proposed by adopting aqueous solution-processed mesoporous silica coating (MSC)-based electrolyte as gate dielec- tric. With optical and electrical synergetic coupling behaviors, the device demonstrates typical synap- tic responses and transition between short-term plasticity and long-term plasticity. With unique field- configurable proton self-modulation behaviors, a pseudo-diode operation mode is demonstrated on the MPEC hybrid transistor. Moreover, the device demonstrates interesting non-associative learning, including habituation and sensitization behavior. The results show that the proposed MPEC hybrid oxide neuromor- phic transistor has great potential in the field of neuromorphic engineering and would have potential in the bionic visual perception platform .

Designer uniform Li plating/stripping through lithium–cobalt alloying hierarchical scaffolds for scalable high-performance lithium-metal anodes

Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capacity. There are, however, several challenges limiting their practical applications, which include low coulombic efficiency, the uncontrollable growth of dendrites and poor rate capability. Here, a rational design of 3D structured lithium metal anodes comprising of in-situ growth of cobalt-decorated nitrogen-doped carbon nanotubes on continuous carbon nanofibers is demonstrated via electrospinning.The porous and free-standing scaffold can enhance the tolerance to stresses resulting from the intrinsic volume change during Li plating/stripping, delivering a significant boost in both charge/discharge rates and stable cycling performance. A binary Co-Li alloying phase was generated at the initial discharge process, creating more active sites for the Li nucleation and uniform deposition. Characterization and density functional theory calculations show that the conductive and uniformly distributed cobalt-decorated carbon nanotubes with hierarchical structure can effectively reduce the local current density and more easily absorb Li atoms, leading to more uniform Li nucleation during plating. The current work presents an advance on scalable and cost-effective strategies for novel electrode materials with 3D hierarchical microstructures and mechanical flexibility for lithium metal anodes.

Design of two-stage membrane reactor for the conversion of coke-oven gas to H_2 and CO

The catalyst function was achieved in two regions in an oxygen permeation membrane reactor： H2 dissociated and reacted with lattice oxygen or oxygen ions to form H20 near the membrane surface. The H20 formed could react with the residual CH4 away from the membrane surface area.

Preparation and oxygen permeation properties of SrFe(Cu)O_(3-δ) dense ceramic membranes

Mixed oxygen-ionic and electronic conducting membranes of SrFe（Cu）O3-δ were prepared by solid-state reaction method. The crystal structure, oxygen nonstoichiometry, and phase stability of the materials were studied by TGA and XRD. Oxygen permeation fluxes through these membranes were studied at operating temperature ranging from 750 to 950 ℃. Results showed that doping Cu in SrFeO3-δ compound had a significant effect on the formation of single-phased perovskite structure. For SrFe1-xCu2O3-δ series materials, the oxygen nonstoichiometry and the oxygen permeation flux increased considerably with the increase of Cu-doping content （x = 0.1-0.3）. The sintering property of the membrane decreased significantly when the Cu substitution amount reached 40%. SrFe0.7Cu0.3O3-δ showed high oxygen permeation flux, but SrCuO2 and Sr2Fe2O5 phases formed in the compound after oxygen permeation test induced cracks in the membrane.

Modeling of a SrCe_(0.95)Yb_(0.05)O_3-αHollow Fibre Membrane Reactor for Methane Coupling

Proton-hole mixed conductor, SrCeo.95Yb0.05O3-α(SCYb), has the potential to be used as a membrane for dehydrogenation reactions such as methane coupling due to its high C2-selectivity and its simplicity for fabricating reactor systems. In addition, the mixed conducting membrane in the hollow fibre geometry is capable of providing high surface area per unit volume. In this study, mechanism of methane coupling reaction on the SCYb membrane was proposed and the kinetic parameters were obtained by regression of experimental data. A mathematical model describing the methane coupling in the SCYb hollow fibre membrane reactor was also developed. With this mathematical model, various operating conditions such as the operation mode, operation pressure and feed concentrations affecting performance of the reactor were investigated. The simulation results show that the cocurrent flow in the reactor exhibits higher conversion of methane and higher yield of ethylene compared to the countercurrent flow. In order to achieve the highest C2 yield, especially of ethylene, pure methane should be used as feed and the operating pressure be 300 kPa. Air can be used as the source of oxygen for the reaction and its optimum feed velocity is twice of the methane feed velocity. The air pressure in the lumen side should be kept the same as or slightly lower than the pressure of shell side.

Preparation and hydrogen permeation properties of BaCe_(0.95)Nd_(0.05)O_(3-δ) membranes

Dense mixed proton and electron conducting membrane made of BaCe0.95Nd0.05O3-δ （BCNd5） was prepared by pressing followed by sintering. X-ray diffraction （XRD） was used to characterize the phase structure of both the powder and the sintered membranes. The microstructure of the sintered membranes was studied by scanning electron microscopy （SEM）. Hydrogen permeation through the BCNd5 membrane was studied using a high temperature permeator. The hydrogen permeation fluxes under wet conditions are higher than those under dry conditions, which is due to H^＋ hopping via surface OH groups. At 925℃, a hydrogen permeation flux of 0.02 mL/min cm^2 was obtained under wet condition, which recommends BCNd5 as a potential material for hydrogen-selective membranes.

Novel SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membrane for hydrogen separation

Dense ceramic membranes with protonic and electronic conductivity have attracted considerable interest in recent years.In this paper,the powders of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were synthesized via the liquid citrate method,and the membranes of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were prepared by pressing followed by sintering.X-ray diffraction(XRD) was used to characterize the phase structure of both the powder and sintered membrane.The microstructure of the sintered membranes was studied by scann...

Novel Ba_(0.5)Sr_(0.5)Fe_(0.8)Zn_(0.2)O_(3-δ) membranes for POM

A novel cobalt-free perovskite based on Ba0.5Sr0.5Fe0.8Zn0.2O3-δ （BSFZ） were prepared by EDTA-citric acid method. The lattice constants of the BSFZ perovskite were characterized by in situ high-temperature X-ray diffraction （HTXRD）. The thermal expansion coefficient of BSFZ is 10.5×10^-6 K^-1, which is lower than that of cobalt-based perovskite materials. The BSFZ membrane was also used to construct reactors for the partial oxidation of methane （POM） to syngas. Results show that the BSFZ membrane can be operated for the POM reaction for more than 100 h without any fractures. The CO selectivity of 97% is obtained. The steady oxygen permeation flux reaches around 2.5 mL/min cm^2 during POM reaction.

Pervoskite-type Bao.sSro.sAl0.1Fe0.9O3-δ as Intermediate-Temperature Solid Oxide Fuel Cell Cathode

A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and electro- structures, electrical con- on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450℃ where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac- terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700℃, A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm2 at 700 ℃ with humidified hydrogen fuel and static air oxidant.

Mixed ion-electron conducting Li_(3)P for efficient cathode prelithiation of all-solid-state Li-ion batteries

All-solid-state batteries(ASSBs)using sulfide electrolytes hold promise for next-generation battery technology.Although using a pure Li metal anode is believed to maximize battery energy density,numerous recent studies have implicated that Li-ion anodes(e.g.,graphite and Si)are more realistic candidates due to their interfacial compatibility with sulfide electrolytes.However,those Li-ion ASSBs suffer from an issue similar to liquid Li-ion batteries,which is a loss of active Li inventory owing to interfacial side reactions between electrode components,resulting in reduced available capacities and shortened cycle life.Herein,for the first time,we explore the potential of Li_(3)P for cathode prelithiation of Li-ion ASSBs.We identify that the crystallized Li_(3)P(c-Li_(3)P)has room-temperature ionic and electronic conductivities of both over 1o-4 s/cm.Such a mixed ion-electron conduct-ing feature ensures that the neat c-LisP affords a high Li+-releasing capacity of 983 mAh/g in ASSBs during the first charging.Moreover,the electro-chemical delithiation of c-LisP takes place below 2 V versus Li+/Li,while its lithiation dominates below 1 V versus Lit/Li.Once used as a cathode prelithiation regent for ASSBs,c-Li_(3)P only functions as a Li+donor without lithiation activity and can adequately compensate for the Li loss with minimal dosage added.Besides mitigating first-cycle Li loss,c-LisP prelithiation can also improve the battery cyclability by sustained release of low-dosage Li+ions in subsequent cycles,which have been embodied in several full ASSBs by coupling a LiCoO2 cathode with various types of anodes(including graphite,in foil,Sb,and Si anode).Our work provides a universal cathode prelithiation strategy for high-efficiency Li-ion AsSBs.

Introducing Ag in Ba_(0.9)La_(0.1)FeO_(3-δ):Combining cationic substitution with metal particle decoration

BaFeO_(3-δ)-derived perovskites are promising cathodes for intermediate temperature solid oxide fuel cells.The activity of these perovskites depends on the number of oxygen vacancies in their lattice,which can be tuned by cationic substitution.Our first-principle calculations show that Ag is a promising substitute for the Fe site,resulting in a reduced oxygen vacancy formation energy compared with the pristine BaFeO_(3-δ).Ag has limited solubility in perovskites,and its introduction generates an Ag metal secondary phase,which influences the cathode performances.In this work,we investigate the matter,using a Ba0:9La0:1Fe_(1-x)AgxO_(3-δ)series of materials as a case study.Acknowledging the limited solubility of Ag in Ba0:9La0:1Fe_(1-x)AgxO_(3-δ),we aim to distinguish the effects of Ag substitution from those of the Ag secondary phase.We observed that Ag substitution increases the number of oxygen vacancies,confirming our calculations,and facilitates the oxygen incorporation.However,Ag substitution lowers the number of holes,in this way reducing the electronic p-type conductivity.On the other hand,Ag metal positively affects the electronic conductivity and helps the redistribution of the electronic charge at the cathode-electrolyte interface.

Highly Stretchable Ionic and Electronic Conductive Fabric

Wearable devices redefine the way people interact with machines.Despite the intensive effort in the design and fabrication of synthetic fibers to improve wearable device properties in terms of electronic and ionic conductivity,stretchability,com-fort,and washability,challenges remain in fabricating single fiber materials that optimize all properties simultaneously.In this work,we demonstrate a highly stretchable,ionic,and electronic conductive fabric via(1)the natural nanoscale chan-nels in fibers for effective ion transportation,(2)confining the electronic conductive material with the cellulose fibers,and(3)decoupling the property degradation of the fiber from deformation using the knitted pattern.The hierarchical structure created by cotton fibers can serve as ionic conductive channels as well as a robust multiscale scaffold to host infiltrated elec-tronic conductive materials.Cotton strands with ionic and electronic conductivity can be knitted into fabrics that are highly stretchable(~300%).Moreover,high ionic and electronic conductivity are observed with 2 S/m and 5 S/m,respectively,even under a strain of 175%.With the inherent advantages of cotton fabrics such as moisture-wicking,washability,comfort,and light-weightiness for wearable applications,our approach of directly functionalized cellulose can potentially be a promising route towards highly stretchable and wearable mixed conductors.

Spatially controlled lithium deposition on Li_(x)Cu_(y)P_(z) arrays enabling highly stable lithium metal batteries

Lithium(Li)metal is a potential anode for high-energy-density batteries because of its low potential and ultrahigh capacity.Nevertheless,the Li dendrites formation,the ununiform Li deposition,and the growth of Li dendrites hamper its application,especially under high deposition capacity/high rate.Here,a spatially controlled Li deposition mode with array-oriented morphology is achieved based on the novel mixed ion/electron-conducting Li_(x)Cu_(y)P_(z) arrays constructed on Cu foil,which can be facile fabricated via an in-situ transformation of metal phosphide.Theoretic calculations indicate the excellent lithiophilicity and low Li diffusion barrier of the arrays,especially for the Li_(2)CuP phase,which are conducive to ho-mogenizing the Li nucleation/deposition of Li.Moreover,such mixed conducting arrays promote fast Li+diffusion via the continuous Li+pathways as well as modulate the Li+flux/electric field.Furthermore,the arrays with enlarged specific surface area and open spaces reduce the local current density and alle-viate the volume fluctuation of Li.Consequently,a dendrite-free Li anode is obtained under a high rate(20 mA cm^(–2))or a high deposition capacity(10 mAh cm^(–2)).In addition,even if the negative/positive ratio reduces to only 1.1,the full cells still perform outstanding stability for over 200 cycles.This work empha-sizes the importance of the design of the framework in terms of the intrinsic properties and structure and reveals a pathway for developing Li metal batteries.

Defect structure and electrical properties of LaSr_3Fe_3O_(10-δ)

As a mixed conductor,LaSr3Fe3O10-δ with triple layer perovskite intergrowth structure can be used as an oxygen separation membrane material and cathode material in solid oxide fuell cells.LaSr3Fe3O10-δ was synthesized via citrate acid route.Iodine titration method was used to determine the average valence of transition metal Fe and oxygen nonstoichiometry δ.Conductivities of LaSr3Fe3O10-δ were measured in the oxygen partial pressure range from 10-2×105 to 1×105 Pa,by Ac four probe method.Seebeck coefficient...

Impedance spectroscopy analysis of CeNbO_4.25

Monoclinic CeNbO4.25 was prepared by solid state reaction. Complex impedance analysis indicated the presence of grain interior effect along with the grain boundary contribution. The values of ionic transference number ti below 423 K were calculated to be about 0.5. The activation energies of ionic conductivity and electronic conductivity were deduced to be 36.0 and 37.2 kJ/mol, re-spectively. The real part of the AC conductivity was frequency dependent. At high frequencies corresponding to the grain interior ef-fect, the non-Debye nature of the AC conductivity was interpreted by the correlated hopping of interstitial oxygen with the electron holes on the basis of the correlated barrier hopping （CBH） model.

Development of Oxide Ceramics for Application in Solid Oxide Fuel Cells

1 Results Solid oxide fuel cells (SOFC) are ceramic fuel cells that convert chemical into electrical energy in a temperature region between 650 ℃ and 1 000 ℃.Systems are currently under development for a variety of applications e.g. for both small and large scale stationary combined heat and power systems but also for the supply of electrical energy in the automotive area. The current objectives in the development of SOFCs is to lower the operating temperature from 850 ℃ down to below 750 ℃ in order to ...