Good Proton Conductivity Research Articles

Effect of Ca doping at A or B sites on electrochemical performance of La1.9In0.1Ce2O7 proton conductors

Fluorite proton conductors La1.8In0.1Ca0.1Ce2O7-δ and La1.9In0.1Ce1.9Ca0.1O7-δ (LICaC and LICCa) were synthesized by solid state reaction. The effect of Ca doping at A site or B site on La1.9In0.1Ce2O7 was studied by X-ray diffraction (XRD), Inductively Coupled Plasma Mass Spectrometry (ICP), scanning electron microscopy (SEM) and electrical conductivity measurement. XRD shows that the LICaC and LICCa were successfully synthesized, and Ca was doped to the expected sites. The measured mass ratios of each element by ICP were in good agreement with their theoretical values. In addition, SEM also found that the surface of the sample was dense without holes. The conductivities of LICaC and LICCa were studied at 400–800 ℃, and their highest conductivities were 7.28×10−4 and 5.56×10−3 S·cm−1, respectively. The conductivity of LICCa doped at the B site is better than that of LICaC doped at the A site. In the wet air at 800 ℃, the proton transference numbers of LICaC and LICCa are 0.5 and 0.52, respectively. LICaC and LICCa were used as electrolytes to prepare fuel cells and their performance was tested. The electrolyte thickness of LICAC and LICCA was about 0.9 mm. At 700 ℃, the maximum power density of LICaC and LICCa electrolyte-based single cells are 124.51 and 162.26 mW cm−2, respectively. The results show that LICCa has good proton conductivity and has potential as an electrolyte for high-performance fuel cells.

Effect of In and Sc Co-doping on electrochemical performance on bulk and grain boundaries of La1.9In0.05Sc0.05Ce2O7 proton conductors

In this paper, fluorite-type proton conductors La1.9In0.1Ce2O7, La1.9In0.05Sc0.05Ce2O7 and La1.9Sc0.1Ce2O7 (referred to as LCO-I, LCO-IS and LCO-S), were synthesized by the low-cost solid-state reaction method. The formation process and structure of single-doped LCO-I and LCO-S and co-doped LCO-IS were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The electrochemical performance was studied using alternating current electrochemical impedance spectroscopy (EIS). XRD results showed that the synthesized material had a fluorite structure, without any impurity phase. SEM micrographs showed that LCO-I, LCO-S and LCO-IS had a fairly dense grain. EDS analysis confirmed that the elemental composition of LCO-I, LCO-S and LCO-IS was evenly distributed and contained no impurities. LCO-IS exhibited superior conductivity among related materials, and the total conductivity of LCO-IS in oxygen was 9.49 × 10−3 S cm−1 at 800 °C. The effects of co-doping on bulk and grain boundary properties were analyzed using the distribution of relaxation time (DRT). The bulk and grain boundary conductivity of co-doped LCO-IS was higher than that of single-doped LCO-I and LCO-S. LCO-IS showed good proton conductivity. In the temperature range of 300–800 °C, the proton conductivity was 1.35 × 10−6–4.43 × 10−3 S cm−1. For LCO-I and LCO-IS electrolyte supported symmetric cells (Ag ǀ LCO-I (LCO-IS) ǀ Ag), their open circuit voltages were 0.99 V and 0.97 V, respectively, at 700 °C, and the power densities were 8.8 mW cm−2 and 9.34 mW cm−2. This demonstrates the potential of LCO-IS to be used in various devices as a proton-conducting electrolyte.

A pyrazine-2,3-dicarboxylic acid hybrid arsenotungstate with decent proton conduction property

A pyrazine-2,3-dicarboxylic acid hybrid arsenotungstate K5Ba5H{Ba[AsW11O37(pzdc)2]2}·22H2O (1, H2pzdc = pyrazine-2,3-dicarboxylic acid) has been synthesized. This compound displayed a dimeric polyanion which consisted of two ancient official cap-shaped [AsW11O37(pzdc)2]9– subunits linked together via a Ba2+ cation. The [AsW11O37(pzdc)2]9– subunit is fused together by a trivacant [AsW9O33]9– fragment and two {WO2(pzdc)} groups. And the [Ba(AsW9O33)2]16– subunit can be simplified into the ferrocene-like structure. What is particularly interesting is that one N and one O atom of the pzdc2– ligand can directly chelate with the W atom to construct the infrequent W–O–C–C–N five-membered ring. Compound 1 exhibits good proton conduction property with the conductivity of 1 can reach up to 2.37× 10–3 S cm-1 at 70 °C under 95% relative humidity.

Novel zirconium phosphate/MXene/ionic liquid membranes for PEM fuel cells operating up to 145°C

In this work, zirconium phosphate, MXene, and a hexyl-based ionic liquid were incorporated into a porous PTFE polymer to synthesize novel composite proton exchange membranes (PEM) for fuel cell applications. The synthesized composite membranes were evaluated for their conductivity at temperatures above the boiling point of water as well as their water uptake properties, thermal stability, surface morphology, and structural characteristics via several characterization techniques. It was observed that the inclusion of MXene had a direct impact on the thermal stability of these membranes and caused substantial structural modifications within the membrane’s matrix. The fabricated membranes displayed a high proton conductivity at room temperature, reaching a peak of approximately 10−2 S/cm when all materials were combined. The membranes exhibited good proton conductivity of 10−4 S/cm at high temperature ranges up to 145℃ and appeared to be stable at higher temperatures, as thermogravimetric analyses showed. The results reported here demonstrate the suitability of the MXene-based synthesized membranes for hydrogen-fueled PEM fuel cell applications. This, in turn, will contribute to enhanced energy efficiency and cleaner energy transition.

Poly (arylene ether ketone sulfone)s functionalized with diethylenetriamine-modified graphene oxide as proton exchange membranes for fuel cells

In this paper, composite proton exchange membranes (PEMs) based on functionalized graphene oxide (NGO) and carboxylated sulfonated poly aryl ether ketone sulfone (C-SPAEKS) were successfully synthesized. Functionalized graphene oxide was synthesized using graphene oxide as a substrate, and then diethylenetriamine (DETA) was chemically bound to the graphene oxide. The 1H NMR, FT-IR and XPS were used to characterize the NGO and composite membranes. The results show that the composite membranes have good proton conductivity, dimensional stability and electrochemical performance. The swelling rate of all the composite membranes was less than 18%, which indicates that they have good dimensional stability. Compared to C-SPAEKS membrane (34.8 mS cm-1 at 20 °C, 109.8 mS cm-1 at 90 °C), the proton conductivities of C-SPAEKS/GO-0.75 membrane (52.4 mS cm-1 at 20 °C, 171.1 mS cm-1 at 90 °C) were significantly improved. Meanwhile, the C-SPAEKS/NGO-0.75 achieved peak power density of 407.77 mW cm-2 at high OCV of 0.9576 V. Such a result is much superior to the C-SPAEKS membrane (0.8973 V, 190.72 mW cm-2) and the Nafion 117 (0.99 V, 302 mW cm-2), and demonstrated good single-fuel cell performance. In summary, it can be well concluded that functionalized GO as filler makes an significant contribution in improving the overall performance of the composite membranes.

Sulfonated poly(ether ether ketone)-Protic ionic Liquid-Based anhydrous Proton-Conducting composite polymer electrolyte membranes for High-Temperature fuel cell applications

A high-temperature polymer electrolyte membrane fuel cell (PEMFC) has enormous potential to produce clean energy with minimal environmental pollution along with high energy density and conversion efficiency. In the present work, anhydrous proton-conducting polymer electrolyte membranes for prospective high-temperature fuel cell application were successfully prepared using different protic ionic liquids (PILs) and sulfonated poly(ether ether ketone) (SPEEK). The protic ionic liquids (PILs), 2-hydroxyethylammonium formate, diethylmethyl ammonium triflate, 1-ethylimidazolium bis(trifluoromethylsulfonyl)imide, 1,2-dimethyl imidazolium bis(trifluoro methylsulfonyl)imide, and diethylmethylammonium methanesulfonate were selected based on their favorable physicochemical properties. The effect of the incorporation of the PIL on the structural, thermal, and electrical transport properties of the composite SPEEK polymer electrolyte membranes was studied. The prepared polymer electrolyte membranes (PEMs) were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and electrochemical impedance spectroscopy (EIS) techniques. FTIR results indicated an interaction between the PIL and the SPEEK, which resulted in homogeneous and flexible membranes. The DSC results confirmed good miscibility and elucidated plasticizing effect of the incorporated PIL on the SPEEK polymer matrix. All the PEMs showed good thermal stability and high-temperature anhydrous proton conductivity, achieving best proton conductivity, ≈8 × 10–3 S cm−1 at 120 °C and low activation energy ≈0.26 eV, making it suitable for prospective high-temperature PEMFC applications.

ZnO sintering aid effect on proton conductivity of BaCe0.6Zr0.3Y0.1O3-δ electrolyte for hydrogen sensors

Proton-conducting solid-state electrolytes, including perovskite-type materials, hold promise for hydrogen sensor development. These sensors leverage the proton conductivity of such materials to detect hydrogen gas presence. However, achieving both high density for gas tightness and good protonic conductivity in these refractory materials can be challenging.In this study, we propose the preparation of dense pellets of BaCe0.6Zr0.3Y0.1O3-δ using ZnO as a sintering aid (BCZY-Zn). These pellets were extensively characterized using X-ray diffraction and electrochemical impedance spectroscopy and compared with pellets sintered without sintering aid (BCZY). Subsequently, BCZY-Zn electrolyte was utilized to fabricate amperometric sensors for hydrogen monitoring. Finally, amperometric measurements were conducted at 500 °C while maintaining a voltage of 150 mV between electrodes. The sensors' performance was evaluated for hydrogen partial pressures ranging from 12 to 100 Pa within an argon atmosphere. Additionally, response and recovery times were calculated.

Dimethylamine-tuned guanidinium arylphosphonate iHOFs and superprotonic conduction Nafion hybrid membranes for DMFCs

The fabrication of proton exchange membranes (PEMs) with excellent conductivity and low methanol permeability is critical but challenging for the further development of high-performance direct methanol fuel cells (DMFCs). In this work, two ionic hydrogen-bonded organic frameworks (iHOF-14 and iHOF-15) are obtained from 1,3,5-tris(4-phosphonophenyl)benzene and guanidine hydrochloride under the control of dimethylamine cations. Due to the abundant hydrogen bonding network, iHOF-14 and iHOF-15 exhibit good proton conductivity of over 10–2 S cm−1. In addition, we dope the iHOFs into Nafion matrix to get the PEMs with richer proton transport pathways and good methanol barrier properties. At 100 °C and 98 % RH, the conductivity of 9 %-iHOF-14/Nafion and 9 %-iHOF-15/Nafion reaches up to 1.53 × 10–1 and 1.78 × 10–1 S cm−1, respectively. The 72 h permeation experiment results show that the methanol permeability of the composite membranes is 73.7 % lower than that of the recast Nafion. The maximum power densities of hybrid membranes for DMFCs reach about 80 mW cm−2, which is 1.5 times higher compared to the recast Nafion. This work not only enriches the high proton conductivity of arylphosphonate iHOFs, but also expands iHOFs/Nafion PEMs materials for DMFCs.

Spontaneous Growth of Perovskite‐Derived Oxide over Double Perovskite Surface for Enhancing Cathodic Performance in Protonic Ceramic Fuel Cells

AbstractRobust catalytic materials with high activity and stability play important roles in energy conversion and storage devices such as protonic ceramic fuel cells (PCFCs), in which a favourable cathode should possess high oxygen ion, proton and electron triple conductivities, and superior surface oxygen exchange kinetics. Herein, a thermal‐driven self‐construction phenomenon in cation‐nonstoichiometric Ba1+xGd1‐xCo2O6‐δ is reported, accordingly developing a new type of nanocomposite, that is, double perovskite BaGdCo2O6‐δ (DP‐BGCO) anchored by perovskite‐derived BaCoO3‐δ (P‐D‐BCO) nanoparticles, which, used as the cathode of PCFCs, demonstrates low area‐specific resistances of 0.053 and 0.026 ohm cm−2 respectively at 650 and 700 °C over BaZr0.3Ce0.5Y0.1Yb0.1O3‐δ protonic electrolyte and attractive peak power densities of 0.87 (650 °C) and 1.15 W cm−2 (700 °C) with outstanding stability, much superior to the similar cell with single‐phase BCO or BGCO cathodes. The synergy between the two components brings the outstanding performance with the mixed oxygen ion and electronic conducting perovskite‐derived oxide showing superior catalytic activity for oxygen reduction reaction while the double perovskite provides good bulk protonic conductivity to enlarge reaction sites. Such selective self‐construction, well manipulated through the A‐site cation stoichiometry engineering, provides a facile way for developing new high‐performance electrocatalysts with broad application potential.

Controlled Assembly of a Dawson-like Antimoniotungstate-Supported Trefoil-type Trimer with Good Proton Conductivity Performance.

With the excellent properties of POM in the field of proton conductivity, the preparation of POM-based proton-conductive materials has burst into life. Herein, an unprecedented Sb-templated all-inorganic trimer Na8H18.64[(SbW14O52)3(Sb2W6.12Ru5.88O18)]·85H2O (1), which is based on tetravacant Dawson-like [SbW14O52]17- blocks and exhibits a trefoil type with D3 symmetry, has been successfully designed and synthesized by the assembly of simple materials with a one-pot hydrothermal method under acidic conditions. Also, compound 1 is systematically characterized by single-crystal X-ray diffraction, PXRD, ESI-MS, IR spectroscopy, UV-vis, elemental analysis, and TGA. Crystal structure data analysis demonstrates that compound 1 is constructed by a hexagonal prismatic heterometallic {Sb2W6.12Ru5.88O18} core and three equivalent {SbW14} units bridged through μ2-O atoms in periphery. Subsequently, further property experiments show that compound 1 exhibits high proton conductivity with a conductivity value (σ) of 3.07 × 10-2 S cm-1 at 75 °C and 80% relative humidity (RH). The activation energy of compound 1 evaluated by the Arrhenius plots is 0.22 eV, which indicates that the Grotthuss mechanism is dominant during the process of proton transfer.

Electrochemical power generation humidity sensor based on WS2 nanoflakes

The electrochemical power generation humidity sensor has received widespread attention due to its zero-power consumption. In this work, we propose an electrochemical power generation humidity sensor using WS2 nanoflakes as the humidity sensing material, without adding additional alkali metal salts (such as LiCl and NaCl) or other added materials or functional group treatments. The results show that the humidity sensor exhibits wide humidity detection range (18.7%−91.5% relative humidity (RH)), fast response/recovery speeds (8.4/5.2 s), good repeatability (20 cycles) and small humidity hysteresis (∼3.4% RH) at room temperature of 25 °C. The output voltage of the humidity sensor is 0.47 V at 91.5% RH. Combined with good water molecule adsorption and proton conductivity of the WS2 nanoflakes, the humidity sensing and power generation mechanism of the WS2 electrochemical power generation humidity sensor can be explained by the redox reactions occurring at the positive and negative electrodes (Cu and Al). Finally, we demonstrate the application of the humidity sensor in respiratory detection. This work provides a useful approach for fabricating electrochemical power generation humidity sensor with a simple single humidity sensing material.

Starch-chitosan-ionic liquids-based composite membranes for high temperature PEM fuel cells applications

This work reports the fabrication of a starch-chitosan-based membrane for proton exchange membrane fuel cell applications at high temperatures, up to 145 °C. The membranes were fabricated by the solution casting method. Ionic liquids (ILs) were incorporated into the fabricated membranes to examine how they impact the proton conductivity. All the modified membranes generally demonstrated very good proton conductivity values in the range of 10−3 S/cm at room temperature. A noticeable increase in the proton conductivity was observed as the temperature was increased for the IL-based membranes. The IL-based membranes gave very high proton conductivities at 145 °C with a percentage increase of 209 % and 900 % compared to the reference membrane that contains starch and chitosan without any additives. The study reported structural interactions, particularly with the hydrophilic groups like the hydroxyl group, as revealed by FTIR analysis. These findings were supported by EIS measurements. The SEM images showed morphological alterations, and the XRD characterization indicated a shift toward an amorphous structure, implying more water retention in the polymer matrix, which explains the improved proton conductivity. The proton conductivity results as well as relevant water uptake properties reported in this work, appear to be promising for fuel cells operating above the boiling point of water.

Solid electrolytes based on cellulose nanocrystals with protic ionic liquid for next-generation fuel cells

AbstractThe search for solid electrolytes which have good proton conductivity in anhydrous conditions, thermal and mechanical stability, and are at the same time environmentally friendly and easy to manufacture is a big challenge which we have undertaken. This work presents new solid electrolytes based on cellulose nanocrystals with protic ionic liquid 1-methylimidazolium bis(trifluoromethylsulfonyl) imide (PIL) which have been obtained and whose thermal and conductivity properties and nanoscale organization has been determined. Two membranes were synthesized which differ as to the amount of absorbed PIL. They show excellent thermal stability up to 200 °C. The maximum value of ionic conductivity is about 10−2 S/m at 200 °C in anhydrous conditions and falls in the range of 10−3–10−2 S/m for temperatures from 150 to 200 °C. The correlation between the transport properties of membranes and their nanostructure has been probed by solid-state nuclear magnetic resonance spectroscopy. The thermal and conductivity properties of the new materials can compete with currently available membranes. Further work on a composite with a similar chemical composition should lead to obtaining a membrane capable of operating in next-generation fuel cells (T > 120 °C).

Promoting densification and grain growth of BaCe0.65Zr0.2Y0.15O3-δ

BaCe0.65Zr0.2Y0.15O3-δ (BCZ20Y15) has raised great interest due to its good protonic conductivity and chemical stability. However, the sintering of the material is considerably challenged by its refractory nature. In the current work, almost fully densified single-phase BCZ20Y15 with grain sizes exceeding 10 μm was successfully fabricated by sintering at 1500 °C by using calcined powders consisting of naturally separated perovskite phases and 0.5 wt% NiO. The role of NiO as sintering aid was elucidated by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Atom Probe Tomography (APT) methods, concerning global and local material composition. Furthermore, the mechanism leading to the promoted densification and grain growth is elucidated based on current experimental results and a comprehensive review of the literature.

Highly Stable Rare Earth Metal-Organic Frameworks for Fluorescence Recognition of Folic Acid, Proton Conduction, and Magnetic Refrigeration.

Four new isostructural rare earth metal-organic frameworks (RE-MOFs) were synthesized and full characterized, namely, {[(CH)2NH2]3[RE2(BTDBA)2(HCOO)]·5H2O·2DMF}n (H4BTDBA = (4',4'''-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid); RE = Eu (JXUST-34), Gd (JXUST-35), Tb (JXUST-36), and Dy (JXUST-37)). The single-crystal structures analysis shows that JXUST-34-37 are chain-based three-dimensional structures. Importantly, JXUST-34 exhibits excellent water, organic solvents, and acid-base stability, which can be used as a fluorescence sensor for folic acid and Al3+ with detection limits of 0.02 mM and 0.05 μM, respectively. The presence of free [(CH)2NH2]+ cations in the channels can engage the proton carrier during proton conduction. JXUST-34-37 display good proton conductivity, and the conductivities vary with relative humidity and temperatures, among which JXUST-37 has the highest conductivity of 9.66 × 10-3 S·cm-1 at 60 °C and 98% RH. The magnetic studies show that the -ΔSm of JXUST-35 reaches 16.13 J kg-1 K-1 at 2 K and ΔH = 7 T. JXUST-34-37 show multifunctional properties of fluorescence sensing, high proton conductivity, and magnetic refrigeration, which provides a new clue for the development of fluorescent-responsive, magnetic-refrigerant, and proton-conductive RE-MOF materials.

Phase transitions, thermal, vibrational (FT-IR and Raman) and optical characterizations, dielectric relaxation and electrical conductivity of a cobalt (II) based hybrid material

The combination of various organic molecules and inorganic fragments into a single hybrid crystalline lattice has sparked much attention for the potential physical properties and applications. The present investigation addresses the characterization of a novel crystalized compound, formulated as (C7H11N2)2CoCl4. In order to characterize the various types of intermolecular interactions in the title compound, the interaction variability of the two independent cations and four chloride atoms is checked via Hirshfeld surface analysis. Indeed, phase structures were characterized using thermogravimetric analysis, differential scanning calorimetry, Infrared and Raman data. Furthermore, UV−vis and PL measurements revealed a semiconductor character of the obtained compound. The calculated direct and indirect band gaps (Egd, Egi) were predicted to be 1.45 and 1.56 eV, respectively. In addition, a phase transition was discovered by thermal analysis at 390 K, and comprehensive dielectric research showed a good agreement with thermal data. Impedance spectroscopy measurements were used to study the electrical and dielectric characteristics of the title compound over a wide range of frequencies and temperatures, 40 Hz–10 MHz and 313–483 K, respectively. The Nyquist plot (Z" versus Z′) from the complex impedance spectrum revealed semicircular arcs described by a Cole-Cole model. Using the Z-view software, a series of Nyquist representations were built and fitted to an equivalent circuit that reflected the behavior of this material. The thermal evolution of the conductivity follows an Arrhenius-type behavior. Also, the real and imaginary parts of dielectric permittivity of (C7H11N2)2CoCl4 at different frequencies were discussed. The presence of grain and grain boundaries is confirmed by the modulus investigations. Electric and dielectric analyses highlight the good protonic conduction of this material.

Proton transfer efficiency enhanced over wide relative humidity: Etidronic acid-modified polyphosphazenes cross-linked polybenzimidazoles membranes

To enhance the proton conductivity and oxidative stability of the proton exchange membrane, an effective strategy to construct robust high-temperature PEMs (HT-PEMs) is proposed. The polyoxy(etidronic acid)phazenes cross-linked m-polybenzimidazole membranes (POHP-mPBI) are prepared by solution casting, thermal-crosslinking and acidification. Polyoxy(etidronic acid sodium)phazenes (Na–POHP) is cross-linkable proton conductors by partially phosphonic acid functionalized polyphosphazenes, which ensures proton transport while retaining the cross-linked groups. After covalent cross-linking between Na–POHP and mPBI, the cross-linked macromolecular structure stably locks the proton conductor in the polymer matrix, which ensures the construction of the proton transfer pathway at wide relative humidity (RH). The molecular dynamics simulation was conducted to verify the hydrogen bonds network with the POHP-mPBI membrane. The POHP-mPBI cross-linked membranes exhibit good oxidative stability, mechanical strength, proton conductivity and low fuel transmembrane permeability. At 180 °C and different RH (100% RH, 50% RH, 30% RH and 0 RH), the proton conductivity of POHP(50)-mPBI membrane is 0.150, 0.076, 0.055 and 0.048 S cm−1, respectively. After the water washing for 96 h, the durability of proton conductivity and weight loss shows a rare decline. The incorporation of proton conductors (POHP) into the PBI matrix by cross-linking is a perspective method to enhance the comprehensive performance of HT-PEM.

Synthesis of Hexagonal Nanophases in the La2O3–MO3 (M = Mo, W) Systems

We report a study of nanophases in the La2O3–MO3 (M = Mo, W) systems, which are known to contain a variety of good oxygen-ion and proton conductors. Mechanically activated La2O3 + MO3 (M = Mo, W) mixtures and the final ceramics have been characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) with Rietveld refinement. The microstructure of the materials has been examined by scanning electron microscopy (SEM), and their conductivity in dry and wet air has been determined using impedance spectroscopy. In both systems, the formation of hexagonal La15M8.5O48 (phase II, 5H polytype) (M = Mo, W) nanophases is observed for the composition 1:1, with exothermic peaks in the DSC curve in the range ~480–520 °C for La15Mo8.5O48 and ~685–760 °C for La15W8.5O48, respectively. The crystallite size of the nanocrystalline tungstates is ~40 nm, and that of the nanocrystalline molybdates is ~50 nm. At higher temperatures (~630–690 and ~1000 °C), we observe irreversible reconstructive phase transitions of hexagonal La15Mo8.5O48 to tetragonal γ-La2MoO6 and of hexagonal La15W8.5O48 to orthorhombic β-La2WO6. We compare the temperature dependences of conductivity for nanoparticulate and microcrystalline hexagonal phases and high-temperature phases differing in density. Above 600 °C, oxygen ion conduction prevails in the coarse-grained La18W10O57 (phase I, 6H polytype) ceramic. Low-density La15W8.5O48 and La15Mo8.5O48 (phase II, 5H polytype) nanoceramics exhibit predominantly electron conduction with an activation energy of 1.36 and 1.35 eV, respectively, in dry air.

Effect of Lu-Doping on Electrical Properties of Strontium Zirconate.

SrZrO3-based perovskites are promising proton-conducting membranes for use in fuel and electrolysis cells, sensors, hydrogen separators, etc., because they combine good proton conductivity with excellent chemical stability. In the present research, the effect of Lu-doping on microstructure, phase composition, and electrical conductivity of SrZr1-xLuxO3-δ (x = 0-0.10) was investigated via X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and impedance spectroscopy. Dense ceramic samples were obtained by the solution combustion synthesis and possessed an orthorhombic perovskite-type structure. The solubility limit of Lu was revealed to lie between x = 0.03 and 0.05. The conductivity of SrZr1-xLuxO3-δ increases strongly with the addition of Lu at x < 0.05 and just slightly changes at x > 0.05. The rise of the water vapor partial pressure results in an increase in the conductivity of SrZr1-xLuxO3-δ ceramics, which confirms their hydration ability and significant contribution of protonic defects to the charge transfer. The highest conductivity was achieved at x = 0.10 (10 mS cm-1 at 700 °C, wet air, pH2O = 0.61 kPa). The conductivity behavior was discussed in terms of the defect formation model, taking into account the improvement in ceramic sintering at high lutetium concentrations.

A facile method to prepare phosphoric polymer networks with high proton conductivity

Phosphoric polymers have good proton conductivity. However, their high hydrophilicity and even water solubility have limited application in proton exchange membranes. In present study, a facile method to prepare phosphoric polymer networks with high proton conductivity is proposed. By adjusting the feeding ratio of P2O5 and hydroxyethyl methacrylate, a series of mixed monomers with different ratios of bis[2-(methacryloyloxy) ethyl] phosphate (BMEP) and 2-(methacryloyloxy) ethyl phosphate (MEP) can be obtained. After copolymerization of BMEP and MEP, the membranes based on the copolymer network exhibit corresponding improved properties (such as increment of mechanical properties and IEC values) with increasing content of BMEP. The highest proton conductivity of the membranes is up to 1.06 × 10−1 S/cm under hydrated state and 7.30 × 10−4 S/cm under anhydrous state.