The electrical conductivity of minerals under extreme conditions is governed by their variations in composition and structure.Constitution water,which is present in various polymorphic phases of olivine,can significan...The electrical conductivity of minerals under extreme conditions is governed by their variations in composition and structure.Constitution water,which is present in various polymorphic phases of olivine,can significantly enhance electrical conductivity under mantle pressure-temperature conditions,therefore playing a key role in proton transport.Despite this,the conductive mechanisms in hydrous olivine,particularly in hydrous ringwoodite,and the dynamic behavior of hydrogen at elevated temperatures,remain poorly understood.In this study,we investigated the proton conduction mechanisms in hydrous ringwoodite through first-principles calculations.Several hydrous models were considered,and ab initio molecular dynamics(AIMD)simulations were employed to simulate hydrous configurations at high temperatures.Calculations based on density functional perturbation theory(DFPT)and vibrational density of states(VDOS)analyses were conducted to probe the stability of hydrous structures,and investigate the dynamic behavior of internal hydrogen.Our results indicate that hydrogen trapped in Mg^(2+)and Fe^(3+)defects exhibits significantly higher mobility than hydrogen trapped in Si^(4+)defects.At elevated temperatures,we observed the ionization of hydrogen from cationic defects,leading to high and highly anisotropic proton conductivity along the[100]crystallographic direction.This thermal ionization-induced anisotropic conductivity is consistent with experimental observations of olivine single crystals.Finally,the conductivity of the 0.79 wt%hydrous ringwoodite structure was found to range from 10^(-0.3)to 10^(0.4)S/m,the 1.19 wt%structure ranged from 10^(0.4)to 10^(0.9)S/m in the transition region,and the 1.62 wt%structure exhibited conductivity ranging from 10^(0.7)to 10^(1.2)S/m.These results are in excellent agreement with prior experimental data,providing further insight into the proton conduction mechanisms of hydrous olivine under extreme mantle conditions.展开更多
High-performance proton exchange membranes are of great importance for fuel cells.Here,we have synthesized polycarboxylate plasticizer modified MIL-101-Cr-NH_(2)(PCP-MCN),a kind of hybrid metal-organic framework,which ...High-performance proton exchange membranes are of great importance for fuel cells.Here,we have synthesized polycarboxylate plasticizer modified MIL-101-Cr-NH_(2)(PCP-MCN),a kind of hybrid metal-organic framework,which exhibits a superior proton conductivity.PCP-MCN nanoparticles are used as additives to fabricate PCP-MCN/Nafion composite membranes.Microstructures and characteristics of PCP-MCN and these membranes have been extensively investigated.Significant enhancement in proton conduction for PCP-MCN around 55℃ is interestingly found due to the thermal motion of the PCP molecular chains.Robust mechanical properties and higher thermal decomposition temperature of the composite membranes are directly ascribed to strong intermolecular interactions between PCP-MCN and Nafion side chains,i.e.,the formation of substantial acid–base pairs(-SO_(3)^(-)…^(+)H–NH-),which further improves compatibility between additive and Nafion matrix.At the same humidity and temperature condition,the water uptake of composite membranes significantly increases due to the incorporation of porous additives with abundant functional groups and thus less crystallinity degree in comparison to pristine Nafion.Proton conductivity(σ)over wide ranges of humidities(30-100%RH at 25℃)and temperatures(30-98℃ at 100%RH)for prepared membranes is measured.The s in PCPMCN/Nafion composite membranes is remarkably enhanced,i.e.0.245 S/cm for PCP-MCN-3wt.%/Nafion is twice that of Nafion membrane at 98℃ and 100%RH,because of the establishment of well-interconnected proton transport ionic water channels and perhaps faster protonation–deprotonation processes.The composite membranes possess weak humidity-dependence of proton transport and higher water uptake due to excellent water retention ability of PCP-MCN.In particular,when 3 wt.%PCP-MCN was added to Nafion,the power density of a single-cell fabricated with this composite membrane reaches impressively 0.480,1.098 W/cm^(2) under 40%RH,100%RH at 60℃,respectively,guaranteeing it to be a promising proton exchange membrane.展开更多
Graphene oxide(GO)filler containing diversified Nafion-based proton exchange membrane(PEM)is studied to know the unique physical and chemical properties and performances of PEM.Nafion-SPEEK 1%-GO 0.75%(NSG-0.75%)compo...Graphene oxide(GO)filler containing diversified Nafion-based proton exchange membrane(PEM)is studied to know the unique physical and chemical properties and performances of PEM.Nafion-SPEEK 1%-GO 0.75%(NSG-0.75%)composite shows the highest proton conductivity of 0.327 S·cm^(-1) at 90℃ and 100%RH(relative humidity)among all the PEM investigated.The descending order of significant proton conductivity is found as;Nafion-sPGO(1%)0.306 S·cm^(-1)>Nafion/ZIF-8@GO 0.280 S·cm^(-1)>Nafion/PGO(2%)0.277 S·cm^(-1)>Nafion/GO-sulfur(3%)0.232 S·cm^(-1)>Nafion/GO-poly-SPM-co-PEGMEMA(1%)0.229 S·cm^(-1)>Nafion/Ce-sPGO(1%)0.215 S·cm^(-1).The proton conductivity,water uptake capacity and ion exchange capacity,hydration number,thermal and oxidative stability,mechanical integrity(tensile strength),maximum power,and current density are found to be increased while activation energy and fuel crossover show a decrement as GO or modified GO is incorporated in the Nafion matrix.Principal component analysis(PCA)predicted a significant correlation between the proton conductivity and the properties;the water uptake capacity,ion exchange capacity,hydration number,maximum power density,and maximum current density are 0.598%,0.688%,0.894%,0.980%,and 0.852%accordingly.A multiple linear model equation of proton conductivity is defined with the parameters of water uptake capacity,ion exchange capacity,hydration number,maximum power density,and maximum current density whereas the regression coefficient is 0.9923.展开更多
Two 3d-4f-5d heterometallic cluster-containing polyoxometalates,formulated as Na_(22){(SbW_(9)O_(33))_(4)[La_(3)W_(6)MO_(18)(H_(2)O)_(8)(CH_(3)COO)_(4)]_(2)}·nH_(2)O(abbreviated as La_(6)M_(2),M=Co/Mn)were synthe...Two 3d-4f-5d heterometallic cluster-containing polyoxometalates,formulated as Na_(22){(SbW_(9)O_(33))_(4)[La_(3)W_(6)MO_(18)(H_(2)O)_(8)(CH_(3)COO)_(4)]_(2)}·nH_(2)O(abbreviated as La_(6)M_(2),M=Co/Mn)were synthesized and structurally characterized.Single-crystal X-ray diffraction analyses reveal that the polyanions of La_(6)Co_(2)and La_(6)Mn_(2)consist of the uncommon 3d-4f-5d clusters{La_(6)W_(12)Co_(2)}and{La_(6)W_(12)Mn_(2)},which are encapsulated by four trilacunary Keggin tungstoantimonates to form the parallelogram-shaped title compounds.Additionally,the polyanions can be extended into a two-dimensional(2D)frame by the linkage of peripheral Na+ions.The inner space of the 2D layer was filled with water molecules and thus an H-bonded network was formed,which is expected to exhibit a fascinating proton conductivity.The study of water-assisted proton conduction demonstrated that La_(6)Co_(2)and La_(6)Mn_(2)were temperature-and humiditydependent proton conductors,respectively,and the proton conductivities could reach 1.3×10^(-2)and 2.3×10^(-2)S/cm at 65℃and 90%RH conditions.展开更多
Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, ...Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, a series of metal-organic complexes were synthesized and characterized under the assembly of electron donor phosphonate, electron acceptor polypyridine ligand and spin carrier rare earth ions. All the compounds exhibited remarkable and reversible responses with photochromism and photomodulated fluorescence, originated from photogenerated radicals via electron transfer from phosphonates to polypyridine ligands. For the Dy analog, slow magnetic relaxation was observed at cryogenic temperature, indicating the single-molecule magnetic behavior. Furthermore, photogenerated radicals could enhance the proton conductive behavior, with about 2 times larger in magnitude after light irradiation for Dy and Y compounds. The introduction of photoluminescence, magnetism and proton conduction into metallic phosphonates can provide potential applications for photochromic materials.展开更多
The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-fie...The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-field have been numerically studied by Runge-Kutta way in our soliton model. The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping of medium, the velocity of its conductivity increases with increasing of the externally applied electric-field and decreasing of the damping coefficient of medium, but the proton-soliton disperses for quite great fluctuation of the ＂force constant and damping coefficient. In the numerical simulation we find that the proton-soliton in our model is thermally stable in a large region of temperature of T ≤ 273 K under influences of damping and externally applied electric-field in ice crvstal. This shows that our model is available and appropriate to ice.展开更多
Two primitive metal-organic frameworks(MOFs),Ni L1 and Ni L2,based on Ni_(8)O_(6)-cluster and ditopic pyrazolate linkers,L1(with rigid alkyne arms)and L2(with flexible alkyne chains),were prepared.The proton conductiv...Two primitive metal-organic frameworks(MOFs),Ni L1 and Ni L2,based on Ni_(8)O_(6)-cluster and ditopic pyrazolate linkers,L1(with rigid alkyne arms)and L2(with flexible alkyne chains),were prepared.The proton conductivities of these MOFs in pristine form and imidazole-encapsulated forms,Im@Ni L1 and Im@Ni L2,were measured and compared.Upon introduction of imidazole molecules,the proton conductivity could be increased by 3 to 5 orders of magnitude and reached as high as 1.72×10^(-2)S/cm(at 98%RH and 80℃).Also,whether imidazole molecules were introduced or not,Ni_(8)O_(6)-based MOFs with L2 in general gave better proton conductivity than those with L1 signifying that flexible side arms indeed assist proton conduction probably via establishment of efficient proton-conducting channels along with formation of highly ordered domains of water/imidazole molecules within the network cavities.Beyond the active Ni_(8)O_(6)-cluster,tuning flexibility of linker pendants serves as an alternative approach to regulate/modulate the proton conductivity of MOFs.展开更多
Herein,we developed for the first time two carboxylic acid based intrinsic proton conductors(COOHCOF-1 and COOH-COF-2)via pre-assembly approach.The obtained COOH-COF-1 and COOH-COF-2 not only show outstanding chemical...Herein,we developed for the first time two carboxylic acid based intrinsic proton conductors(COOHCOF-1 and COOH-COF-2)via pre-assembly approach.The obtained COOH-COF-1 and COOH-COF-2 not only show outstanding chemical and thermal stabilities,but also exhibit superhigh intrinsic proton conductive behaviors.Especially,the intrinsic proton conductivity of COOH-COF-2 is up to 2.6×10^(−3) S/cm at 353 K and 98%RH,which is the highest value among all the reported acid functionalized COFs.This work lights up the way for the rational design of functional COFs with remarkably intrinsic proton conducting performance and related practical applications.展开更多
A γ - type of layered zirconium hydrogen phosphate, Zr(HPO 4) 2·2H 2O( γ ZrP), was synthesized under hydrothermal conditions and characterized by powder X ray diffraction and thermogravimetric analysis....A γ - type of layered zirconium hydrogen phosphate, Zr(HPO 4) 2·2H 2O( γ ZrP), was synthesized under hydrothermal conditions and characterized by powder X ray diffraction and thermogravimetric analysis. The temperature dependence of the proton conductivity in γ ZrP was investigated in a temperature range of 23￣413 ℃ by ac impedance spectroscopy. The variation of the conductivity with water loss and phase transitions was observed. The best proton conductivity in γ ZrP is 6×10 -4 S·cm -1 at 60 ℃. The proton conductivities in the dehydrated sample are ￣10 -5 at 150 ℃ and ￣10 -4 S·cm -1 at 350 ℃, respectively. The conductivities as a function of humidity in the temperature range of 120￣200 ℃ were measured.展开更多
A heterometal-organic framework {[Pr2Ca（betc）2（H2O）7]·H2O}n（1） was prepared by the hydrothermal reaction of 1,2,4,5-benzenetetracarboxylic acid（H4betc） with Pr（NO3）3 and CaCO3, and further characterized...A heterometal-organic framework {[Pr2Ca（betc）2（H2O）7]·H2O}n（1） was prepared by the hydrothermal reaction of 1,2,4,5-benzenetetracarboxylic acid（H4betc） with Pr（NO3）3 and CaCO3, and further characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Complex 1 crystallizes in triclinic, space group P1 with a = 7.3668（12）, b = 10.1726（14）, c = 11.2264（15） A, a = 100.404（2）, b = 106.113（3）, g = 109.158（3）o, V = 728.48（19） A3, Mr = 966.26, Z = 1, F（000） = 470, Dc = 2.203 g/cm3, m（Mo Kα） = 3.585 mm-1, the final R = 0.0195 and w R = 0.0470（I 〉 2s（I））. Complex 1 is a 3D network with pcu topology with 1D porosity and rich hydrogen-bonding interactions. The proton conductivity of complex 1 was also studied under ~97% relative humidity and the different temperature conditions.展开更多
The proton conductive electrolytes operating under high temperature(100-200℃)are highly desired for high temperature proton exchange membrane fuel cells(HTPEMFC),which possess high CO tolerance,easy thermal-water man...The proton conductive electrolytes operating under high temperature(100-200℃)are highly desired for high temperature proton exchange membrane fuel cells(HTPEMFC),which possess high CO tolerance,easy thermal-water management,and high efficiency.However,conventional proton exchange membranes face the challenge of proton carrier leaking.To conquer such issue,in this work,the nanometer-sized proton transport channels are constructed in ZIF-8 membrane,in which deep eutectic solvents(DES)act as proton carriers to build continuous hydrogen-bonding networks.The microporous structure of ZIF-8 would inhibit DES leaking by size sieving.An excellent proton conductivity is achieved in the DES@ZIF-8 membrane,which is 1.21×10^(-2)S cm^(-1)at 180℃.Furthermore,it is discovered that weak electron donors could optimize the proton transport pathway by tuning the structure and HOMO of hydrogen-bonding networks,which would lower the activation energy for proton hopping and enhance rapid proton transport.As a proof of concept,the DES@ZIF-8 membrane is fabricated directly into a H_(2)/O_(2)HTPEMFC.This work provides not only a kind of efficient proton conducive electrolytes,but also theoretical support for improving proton conductivity by optimizing hydrogen-bonding networks.展开更多
Multicomponent crystalline materials construct more complex and diversified structures with different combinations and modes,which expands the material structure space and application fields.In this work,we have succe...Multicomponent crystalline materials construct more complex and diversified structures with different combinations and modes,which expands the material structure space and application fields.In this work,we have successfully synthesized two twocomponent ionic hydrogen-bonded organic frameworks(iHOF-32 and iHOF-33)and a three-component iHOF(iHOF-34).Guanidine hydrochloride which is rich in N and H and has a short chain length strengthens the hydrogen bonding network of iHOF,thereby aiding in the efficient migration of protons.The rigid architecture of 1,1'-diamino-4,4'-bipyridine diiodide furnishes additional scaffolding for the iHOFs and enhances its robustness under harsh conditions.iHOF-34 accomplishes the combination of the ultra-high proton conductivity of iHOF-32 and the robustness of iHOF-33 by the synergistic interaction among the three components of ligands.In addition,iHOF-34 was fabricated as a composite membrane with a peak proton conductivity of 1.55×10^(-1)S cm^(-1),which is 3.8 times higher than that of recast Nafion,and has extensive potential in fuel cells.The self-assembly strategy of multicomponent HOFs opens up new avenues for constructing diverse structures while promising new opportunities for applications in the fields of proton conduction and energy storage.展开更多
Enhancing the proton conductivity of proton exchange membranes(PEMs)is essential to expand the applications of proton exchange membrane fuel cells(PEMFCs).Inspired by the proton conduction mechanism of bacteriorhodops...Enhancing the proton conductivity of proton exchange membranes(PEMs)is essential to expand the applications of proton exchange membrane fuel cells(PEMFCs).Inspired by the proton conduction mechanism of bacteriorhodopsin,cucurbit[n]urils(CB[n],where n is the number of glycoluril units,n=6,7,or 8)are introduced into sulfonated poly(ether ether ketone)(SPEEK)matrix to fabricate hybrid PEMs,employing a nature-inspired chemical engineering(NICE)methodology.The carbonyl groups of CB[n]act as proton-conducting sites,while the host–vip interaction between CB[n]and water molecules offers extra protonconducting pathways.Additionally,the molecular size of CB[n]aids in their dispersion within the SPEEK matrix,effectively bridging the unconnected proton-conducting sulfonic group domains within the SPEEK membrane.Consequently,all hybrid membranes exhibit significantly enhanced proton conductivity.Notably,the SPEEK membrane incorporating 1 wt.%CB[8](CB[8]/SPEEK-1%)demonstrates the highest proton conductivity of 198.0 mS·cm^(−1) at 60°C and 100%relative humidity(RH),which is 228%greater than that of the pure SPEEK membrane under the same conditions.Moreover,hybrid membranes exhibit superior fuel cell performance.The CB[8]/SPEEK-1%membrane achieves a maximum power density of 214 mW·cm^(−2),representing a 140%improvement over the pure SPEEK membrane(89 mW·cm^(−2))at 50°C and 100%RH.These findings serve as a foundation for constructing continuous proton-conducting pathways within membranes by utilizing supramolecular macrocycles as fuel cell electrolytes and in other applications.展开更多
A series of solid solutions with high content of Tb_(2)O_(3)-(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.667-0.830)are synthesized in the Tb_(2)O_(3)-TiO_(2)system via co-precipitation and/or mechanical activation.This is followed ...A series of solid solutions with high content of Tb_(2)O_(3)-(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.667-0.830)are synthesized in the Tb_(2)O_(3)-TiO_(2)system via co-precipitation and/or mechanical activation.This is followed by high-temperature annealing for 4-22 h.The X-ray diffrac-tion method showed that the fluorite structure was realized for(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.75-0.817).The solid solution Tb_(3.12)Ti_(0.88)O_(6.44)(64mol%Tb_(2)O_(3)(x=0.78))with a fluorite structure exhibited a maximum hole conductivity of~22 S/cm at 600℃.To separate the ionic component of the conductivity in the electronic conductor Tb_(3.12)Ti_(0.88)O_(6.44),its high entropy analogue,(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44),was synthesized in which all rare-earth elements(REE)cations exhibited valency of+3.Consequently,the contribution of ionic(proton)conductivity(~7×10^(−6)S/cm at 600℃)was revealed with respect to the background of dominant hole conductivity.The proton conduct-ivity of high-entropy oxide(HEО)(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44)was confirmed by the detection of the isotope effect,where the mobility of the heavier O-D ions was lower than that of the O-H hydroxyls,resulting in lower conductivity in D_(2)O vapors when com-pared to H_(2)O.展开更多
To develop proton-conducting materials with high hydrothermal and acid-base stability and to elucidate the proton-transport mechanism through visualized structural analysis,two new lanthanum phosphite-oxalates with 3D...To develop proton-conducting materials with high hydrothermal and acid-base stability and to elucidate the proton-transport mechanism through visualized structural analysis,two new lanthanum phosphite-oxalates with 3D frameworks,designated as[La(HPO_(3))(C_(2)O_(4))0.5(H_(2)O)_(2)](La‑1)and(C_(6)H_(16)N_(2))(H_(3)O)[La_(2)(H_(2)PO_(3))_(3)(C_(2)O_(4))_(3)(H_(2)O)](La‑2)(C_(6)H_(14)N_(2)=cis-2,6-dimethylpiperazine),were prepared by hydrothermal and solvothermal conduction,respectively.La‑1 was constructed with lanthanum phosphite 2D layers and C_(2)O_(4)^(2-)groups,whereas La‑2 was constructed with lanthanum oxalate 2D layers and H_(2)PO^(3-)groups.Alternating current(AC)impedance spectra indicate that the pro-ton conductivities of both compounds could reach 10^(-4)S·cm^(-1)and remain highly durable at 75℃and 98%of rela-tive humidity(RH).Due to the abundance of H-bonds in La‑2,theσof La‑2 was higher than that of La‑1.La‑1 exhibited excellent water and pH stability.CCDC:2439965,La‑1;443776,La‑2.展开更多
The sulfonated poly(α-methyl styrene-b-isobutylene-b-α-methyl styrene)copolymers(S-ASIBS)with the average molar percentage of sulfonic acid(-SO_(3)H)groups(SP)ranging from 3.6 mol%to 14.3 mol%could be synthesized by...The sulfonated poly(α-methyl styrene-b-isobutylene-b-α-methyl styrene)copolymers(S-ASIBS)with the average molar percentage of sulfonic acid(-SO_(3)H)groups(SP)ranging from 3.6 mol%to 14.3 mol%could be synthesized by sulfonation of ASIBS with acetyl sulfate.The hydrophilic ionic channels were generated for proton exchange membranes(PEMs)by ion aggregation of-SO_(3)H groups and microphase separation between hydrophobic polyisobutylene and hydrophilic sulfonated poly(α-methyl styrene)segments in S-ASIBS.The proton transport ability was improved while oxidative stability was decreased by increasing SP in S-ASIBS.The appropriate SP of about 12.7 mol%in S-ASIBS provides the available PEMs with high proton transport ability,low methanol permeability and good oxidative stability.The absence of active tertiary hydrogen atoms along S-ASIBS copolymer chains avoids their attack by peroxy radicals.The residual rates of weight(RW)and proton conductivity(Rσ)of S-ASIBS-12.7 membrane after oxidation treatment for 916 h were 84.3%and 88.1%respectively,near to those of commercial Nafion 117(RW=87.9%,Rσ=90.3%).The membrane electrode assembly(MEA)could be prepared by using various S-ASIBS as PEMs for direct methanol fuel cell.The single cell with S-ASIBS-12.7 MEA behaves high performance of open circuit voltage(OCV)of 548 mV and peak power density(Pmax)of 36.1 mW·cm^(-2),which is similar to those of Nafion 117(OCV=506 mV,P_(max)=35.6 mW·cm^(-2)).To the best of our knowledge,this is the first example of advanced S-ASIBS membrane with high proton conductivity,excellent fuel barrier property and remarkable oxidative stability for promising PEMs.展开更多
Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge ...Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge behind self-supporting CONs membrane lies in weak noncovalent interlayer interactions and thus loose stacking,insufficient strength and structure stabilities.Herein,we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs(CON-NH2)to negatively-charged sulfonated CONs(CON-SO_(3)H).Ultrathin and large lateral sized CON-SO_(3)H and CON-NH2 are synthesized,followed by restacking to prepare freestanding CONs membrane with CON-SO_(3)H as the membrane bulk.Benefiting from effective interlayer interconnection due to strong electrostatic interaction,the obtained CON-SO_(3)H/CON-NH2 membrane displays features of ultrahigh integrity,dense stacking,eminent water/acid/base/organic solvents stabilities and mechanical strength(109 MPa).The shortened-SO_(3)H distance contributes to construct site-continuous transfer pathways,and the deprotonated-SO_(3)H and protonated-NH2 form acid-base pairs to decrease interfacial resistance,which impart membrane superior proton conductivity of 486 mS cm^(-1)(80℃,100%RH).This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.展开更多
The thiol-imidazole functionalized(p-triphenyl-pentafluorobenzaldehyde)polymer(IMPTP)was prepared and quaternized with different side chains to obtain imidazolium-modified Me-IMPTP,He-IMPTP and BIM-IMPTP membranes for...The thiol-imidazole functionalized(p-triphenyl-pentafluorobenzaldehyde)polymer(IMPTP)was prepared and quaternized with different side chains to obtain imidazolium-modified Me-IMPTP,He-IMPTP and BIM-IMPTP membranes for application in high-temperature proton exchange membrane fuel cells(HT-PEMFCs).The presence of the thioether group in the polymers enabled radical scavenging for antioxidant properties,while imidazolium cations interacted strongly with H_(2)PO_(4) to prevent phosphoric acid(PA)leaching.The prepared BIM-IMPTP membrane incorporating bisimidazolium cation string with a long alkyl spacer demonstrated the highest mass retention of 82.93%after being immersed in Fenton's reagent for 24 h.Additionally,the PA-doped BIM-IMPTP membranes exhibited excellent PA retention under high-humidity conditions(80℃/100%RH).The single cell equipped with the BIM-IMPTP/320%PA membrane achieved a maximum power density(PDmax)of 945 mW cm^(-2)at 160℃.Among the four membranes with a similar acid doping content(ADC),the BIM-IMPTP/163%PA membrane with bis-cation pairs in the side chains exhibited a well-developed microphase-separated structure and high proton conductivity(119.0 mS cm^(-1)at 180℃).The single cell assembled with BIM-IMPTP/163%PA membrane maintained a PDmax of 613 mW cm^(-2)at 160℃ and demonstrated long-term operational stability under both 150/400 mA cm^(-2)and 80℃/200 mA cm^(-2)conditions.These results indicate that the introduction of thioether and bis-cation pairs in the structural design of polymers contributes significantly to the long-term stability of HT-PEMs.展开更多
Highly reduced molybdenum red(MR)clusters have emerged as a new type of polyoxomolybdates(POMos)and showed great potential as electron/proton reservoirs for energy conversion and storage,as well as for catalysis.Howev...Highly reduced molybdenum red(MR)clusters have emerged as a new type of polyoxomolybdates(POMos)and showed great potential as electron/proton reservoirs for energy conversion and storage,as well as for catalysis.However,the limited structural diversity of MR clusters significantly hinders further exploration of their potential as functional materials.Herein,we describe the synthesis of a novel highly reduced MR cluster{Mo_(49)}(compound 1)based on rational assembly of a variety of basic building blocks(BBs).In addition to the well-established BBs found in the family of MR clusters,the unique tetrahedral{MoVI 4}BB plays a key role in directing the assembly to afford trigonal pyramid-like structure of compound 1,which consists of 49 Mo and 148 O atoms with a high reduction degree of 73%.Moreover,at 80℃and 98%relative humidity(RH),the pellet sample of compound 1 displays good proton conductivity of 7.88×10^(-3)S/cm owing to the efficient hydrogen-bonded network built from the surface oxygen atoms,protons and vip water molecules.This research offers new insights into the assembly and synthesis of MR clusters through a BB strategy and manifests their significant potential for advanced applications.展开更多
Highly reduced polyoxometalates(POMs) are predicted to be used as rather high energy density materials;however,it still suffers from the limited cluster species and reduction ratio.Here we demonstrate that it is possi...Highly reduced polyoxometalates(POMs) are predicted to be used as rather high energy density materials;however,it still suffers from the limited cluster species and reduction ratio.Here we demonstrate that it is possible to employ the building block strategy to generate a highly reduced polyoxomolybdate(C_(2)H_(8)N)_(14)(NH_(4))_(4)H_(14)[Mo_(48)-ⅤMo_(26)ⅥO_(202)(OH)_(12)(SO_(4))_(6)]·46H_(2)O(Mo_(74)).The fundamental Mo-based{Mo_x}(x=4,5,and 6) building blocks,which are templated by tetra-coordinated anions{MoO_(4)}or{SO_(4)},not only lay foundation for the formation of Mo_(74) featuring an unprecedented reduction ratio of 65%,but also give rise to SBBs-mediated(secondary building blocks) supramolecular dense packing interactions among the isolated Mo_(74) clusters that are favorable for proton conduction.Remarkably,high proton conductivity(2.04×10^(-2)S cm^(-1)) had been realized at 50℃ and 90% relative humidity,revealing one of the well-known POMs-based crystalline proton conducting materials.This result highlights that this building block approach possesses great potential in producing highly reduced POM systems that can achieve controllable reduced ratio and desirable properties.展开更多
基金supported by the National Natural Science Foundation of China(41930112,91755215)the Sichuan Students'Innovation and entrepreneurship training program(s202310616086).
文摘The electrical conductivity of minerals under extreme conditions is governed by their variations in composition and structure.Constitution water,which is present in various polymorphic phases of olivine,can significantly enhance electrical conductivity under mantle pressure-temperature conditions,therefore playing a key role in proton transport.Despite this,the conductive mechanisms in hydrous olivine,particularly in hydrous ringwoodite,and the dynamic behavior of hydrogen at elevated temperatures,remain poorly understood.In this study,we investigated the proton conduction mechanisms in hydrous ringwoodite through first-principles calculations.Several hydrous models were considered,and ab initio molecular dynamics(AIMD)simulations were employed to simulate hydrous configurations at high temperatures.Calculations based on density functional perturbation theory(DFPT)and vibrational density of states(VDOS)analyses were conducted to probe the stability of hydrous structures,and investigate the dynamic behavior of internal hydrogen.Our results indicate that hydrogen trapped in Mg^(2+)and Fe^(3+)defects exhibits significantly higher mobility than hydrogen trapped in Si^(4+)defects.At elevated temperatures,we observed the ionization of hydrogen from cationic defects,leading to high and highly anisotropic proton conductivity along the[100]crystallographic direction.This thermal ionization-induced anisotropic conductivity is consistent with experimental observations of olivine single crystals.Finally,the conductivity of the 0.79 wt%hydrous ringwoodite structure was found to range from 10^(-0.3)to 10^(0.4)S/m,the 1.19 wt%structure ranged from 10^(0.4)to 10^(0.9)S/m in the transition region,and the 1.62 wt%structure exhibited conductivity ranging from 10^(0.7)to 10^(1.2)S/m.These results are in excellent agreement with prior experimental data,providing further insight into the proton conduction mechanisms of hydrous olivine under extreme mantle conditions.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.12075172,12375288,12205089,and 12105048)National Key R&D Program of China(Grant No.2019YFA0210003)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110817).
文摘High-performance proton exchange membranes are of great importance for fuel cells.Here,we have synthesized polycarboxylate plasticizer modified MIL-101-Cr-NH_(2)(PCP-MCN),a kind of hybrid metal-organic framework,which exhibits a superior proton conductivity.PCP-MCN nanoparticles are used as additives to fabricate PCP-MCN/Nafion composite membranes.Microstructures and characteristics of PCP-MCN and these membranes have been extensively investigated.Significant enhancement in proton conduction for PCP-MCN around 55℃ is interestingly found due to the thermal motion of the PCP molecular chains.Robust mechanical properties and higher thermal decomposition temperature of the composite membranes are directly ascribed to strong intermolecular interactions between PCP-MCN and Nafion side chains,i.e.,the formation of substantial acid–base pairs(-SO_(3)^(-)…^(+)H–NH-),which further improves compatibility between additive and Nafion matrix.At the same humidity and temperature condition,the water uptake of composite membranes significantly increases due to the incorporation of porous additives with abundant functional groups and thus less crystallinity degree in comparison to pristine Nafion.Proton conductivity(σ)over wide ranges of humidities(30-100%RH at 25℃)and temperatures(30-98℃ at 100%RH)for prepared membranes is measured.The s in PCPMCN/Nafion composite membranes is remarkably enhanced,i.e.0.245 S/cm for PCP-MCN-3wt.%/Nafion is twice that of Nafion membrane at 98℃ and 100%RH,because of the establishment of well-interconnected proton transport ionic water channels and perhaps faster protonation–deprotonation processes.The composite membranes possess weak humidity-dependence of proton transport and higher water uptake due to excellent water retention ability of PCP-MCN.In particular,when 3 wt.%PCP-MCN was added to Nafion,the power density of a single-cell fabricated with this composite membrane reaches impressively 0.480,1.098 W/cm^(2) under 40%RH,100%RH at 60℃,respectively,guaranteeing it to be a promising proton exchange membrane.
文摘Graphene oxide(GO)filler containing diversified Nafion-based proton exchange membrane(PEM)is studied to know the unique physical and chemical properties and performances of PEM.Nafion-SPEEK 1%-GO 0.75%(NSG-0.75%)composite shows the highest proton conductivity of 0.327 S·cm^(-1) at 90℃ and 100%RH(relative humidity)among all the PEM investigated.The descending order of significant proton conductivity is found as;Nafion-sPGO(1%)0.306 S·cm^(-1)>Nafion/ZIF-8@GO 0.280 S·cm^(-1)>Nafion/PGO(2%)0.277 S·cm^(-1)>Nafion/GO-sulfur(3%)0.232 S·cm^(-1)>Nafion/GO-poly-SPM-co-PEGMEMA(1%)0.229 S·cm^(-1)>Nafion/Ce-sPGO(1%)0.215 S·cm^(-1).The proton conductivity,water uptake capacity and ion exchange capacity,hydration number,thermal and oxidative stability,mechanical integrity(tensile strength),maximum power,and current density are found to be increased while activation energy and fuel crossover show a decrement as GO or modified GO is incorporated in the Nafion matrix.Principal component analysis(PCA)predicted a significant correlation between the proton conductivity and the properties;the water uptake capacity,ion exchange capacity,hydration number,maximum power density,and maximum current density are 0.598%,0.688%,0.894%,0.980%,and 0.852%accordingly.A multiple linear model equation of proton conductivity is defined with the parameters of water uptake capacity,ion exchange capacity,hydration number,maximum power density,and maximum current density whereas the regression coefficient is 0.9923.
基金supported by the National Natural Science Foundation of China(No.22071045)the Excellent Youth Science Fund Project of Henan Province(No.202300410042)+2 种基金the Natural Science Foundation of Henan Province(No.232300420372)Henan Universitythe State Key Laboratory of Physical Chemistry of the Solid Surface of Xiamen University。
文摘Two 3d-4f-5d heterometallic cluster-containing polyoxometalates,formulated as Na_(22){(SbW_(9)O_(33))_(4)[La_(3)W_(6)MO_(18)(H_(2)O)_(8)(CH_(3)COO)_(4)]_(2)}·nH_(2)O(abbreviated as La_(6)M_(2),M=Co/Mn)were synthesized and structurally characterized.Single-crystal X-ray diffraction analyses reveal that the polyanions of La_(6)Co_(2)and La_(6)Mn_(2)consist of the uncommon 3d-4f-5d clusters{La_(6)W_(12)Co_(2)}and{La_(6)W_(12)Mn_(2)},which are encapsulated by four trilacunary Keggin tungstoantimonates to form the parallelogram-shaped title compounds.Additionally,the polyanions can be extended into a two-dimensional(2D)frame by the linkage of peripheral Na+ions.The inner space of the 2D layer was filled with water molecules and thus an H-bonded network was formed,which is expected to exhibit a fascinating proton conductivity.The study of water-assisted proton conduction demonstrated that La_(6)Co_(2)and La_(6)Mn_(2)were temperature-and humiditydependent proton conductors,respectively,and the proton conductivities could reach 1.3×10^(-2)and 2.3×10^(-2)S/cm at 65℃and 90%RH conditions.
基金supported by the National Natural Science Foundation of China (Nos. 21901133 and 22071126)Key Research and Development Project of Shandong Province (No. 2019GGX102006)the State Key Laboratory of Fine Chemicals (No. KF1905)。
文摘Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, a series of metal-organic complexes were synthesized and characterized under the assembly of electron donor phosphonate, electron acceptor polypyridine ligand and spin carrier rare earth ions. All the compounds exhibited remarkable and reversible responses with photochromism and photomodulated fluorescence, originated from photogenerated radicals via electron transfer from phosphonates to polypyridine ligands. For the Dy analog, slow magnetic relaxation was observed at cryogenic temperature, indicating the single-molecule magnetic behavior. Furthermore, photogenerated radicals could enhance the proton conductive behavior, with about 2 times larger in magnitude after light irradiation for Dy and Y compounds. The introduction of photoluminescence, magnetism and proton conduction into metallic phosphonates can provide potential applications for photochromic materials.
基金The project supported by National Natural Science Foundation of China under Grant No. 90306015
文摘The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-field have been numerically studied by Runge-Kutta way in our soliton model. The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping of medium, the velocity of its conductivity increases with increasing of the externally applied electric-field and decreasing of the damping coefficient of medium, but the proton-soliton disperses for quite great fluctuation of the ＂force constant and damping coefficient. In the numerical simulation we find that the proton-soliton in our model is thermally stable in a large region of temperature of T ≤ 273 K under influences of damping and externally applied electric-field in ice crvstal. This shows that our model is available and appropriate to ice.
基金the National Natural Science Foundation of China(No.21871061)the Foundation of Basic and Applied Basic Research of Guangdong Province(No.2021A1515010274)+2 种基金the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032)the Science and Technology Planning Project of Guangdong Province(No.2021A0505030066)the Science and Technology Program of Guangzhou(No.201807010026)。
文摘Two primitive metal-organic frameworks(MOFs),Ni L1 and Ni L2,based on Ni_(8)O_(6)-cluster and ditopic pyrazolate linkers,L1(with rigid alkyne arms)and L2(with flexible alkyne chains),were prepared.The proton conductivities of these MOFs in pristine form and imidazole-encapsulated forms,Im@Ni L1 and Im@Ni L2,were measured and compared.Upon introduction of imidazole molecules,the proton conductivity could be increased by 3 to 5 orders of magnitude and reached as high as 1.72×10^(-2)S/cm(at 98%RH and 80℃).Also,whether imidazole molecules were introduced or not,Ni_(8)O_(6)-based MOFs with L2 in general gave better proton conductivity than those with L1 signifying that flexible side arms indeed assist proton conduction probably via establishment of efficient proton-conducting channels along with formation of highly ordered domains of water/imidazole molecules within the network cavities.Beyond the active Ni_(8)O_(6)-cluster,tuning flexibility of linker pendants serves as an alternative approach to regulate/modulate the proton conductivity of MOFs.
基金supported by the National Natural Science Foundation of China(Nos.21978138 and 22035003)the Fundamental Research Funds for the Central Universities(Nankai University)the Haihe Laboratory of Sustainable Chemical Transformations(No.YYJC202101).
文摘Herein,we developed for the first time two carboxylic acid based intrinsic proton conductors(COOHCOF-1 and COOH-COF-2)via pre-assembly approach.The obtained COOH-COF-1 and COOH-COF-2 not only show outstanding chemical and thermal stabilities,but also exhibit superhigh intrinsic proton conductive behaviors.Especially,the intrinsic proton conductivity of COOH-COF-2 is up to 2.6×10^(−3) S/cm at 353 K and 98%RH,which is the highest value among all the reported acid functionalized COFs.This work lights up the way for the rational design of functional COFs with remarkably intrinsic proton conducting performance and related practical applications.
文摘A γ - type of layered zirconium hydrogen phosphate, Zr(HPO 4) 2·2H 2O( γ ZrP), was synthesized under hydrothermal conditions and characterized by powder X ray diffraction and thermogravimetric analysis. The temperature dependence of the proton conductivity in γ ZrP was investigated in a temperature range of 23￣413 ℃ by ac impedance spectroscopy. The variation of the conductivity with water loss and phase transitions was observed. The best proton conductivity in γ ZrP is 6×10 -4 S·cm -1 at 60 ℃. The proton conductivities in the dehydrated sample are ￣10 -5 at 150 ℃ and ￣10 -4 S·cm -1 at 350 ℃, respectively. The conductivities as a function of humidity in the temperature range of 120￣200 ℃ were measured.
基金supported by the National Natural Science Foundation of China(21401147 and 21301134)Basic Research Program of Natural Science from Shaanxi Provincial Government(2015JQ2032)+2 种基金Scientific Research Program from Education Department of Shaanxi Provincial Government(2013JK0654)Opening Foundation from State Key Laboratory of Coordination Chemistry in Nanjing University(201219)the Program for Distinguished Young Scholars of Xi’an Polytechnic University(201403)
文摘A heterometal-organic framework {[Pr2Ca（betc）2（H2O）7]·H2O}n（1） was prepared by the hydrothermal reaction of 1,2,4,5-benzenetetracarboxylic acid（H4betc） with Pr（NO3）3 and CaCO3, and further characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Complex 1 crystallizes in triclinic, space group P1 with a = 7.3668（12）, b = 10.1726（14）, c = 11.2264（15） A, a = 100.404（2）, b = 106.113（3）, g = 109.158（3）o, V = 728.48（19） A3, Mr = 966.26, Z = 1, F（000） = 470, Dc = 2.203 g/cm3, m（Mo Kα） = 3.585 mm-1, the final R = 0.0195 and w R = 0.0470（I 〉 2s（I））. Complex 1 is a 3D network with pcu topology with 1D porosity and rich hydrogen-bonding interactions. The proton conductivity of complex 1 was also studied under ~97% relative humidity and the different temperature conditions.
基金supported by the National Natural Science Foundation of China(22209060,22208126)the Natural Science Foundation of Jiangsu Province(BK20220539,BK20210782,BK20210774)+2 种基金the National Key R&D Program of China(2018YFE0121200)the China Postdoctoral Science Foundation(2023M731359,2024T170356)the Young Talent Support Fund from Jiangsu University(22JDG018)。
文摘The proton conductive electrolytes operating under high temperature(100-200℃)are highly desired for high temperature proton exchange membrane fuel cells(HTPEMFC),which possess high CO tolerance,easy thermal-water management,and high efficiency.However,conventional proton exchange membranes face the challenge of proton carrier leaking.To conquer such issue,in this work,the nanometer-sized proton transport channels are constructed in ZIF-8 membrane,in which deep eutectic solvents(DES)act as proton carriers to build continuous hydrogen-bonding networks.The microporous structure of ZIF-8 would inhibit DES leaking by size sieving.An excellent proton conductivity is achieved in the DES@ZIF-8 membrane,which is 1.21×10^(-2)S cm^(-1)at 180℃.Furthermore,it is discovered that weak electron donors could optimize the proton transport pathway by tuning the structure and HOMO of hydrogen-bonding networks,which would lower the activation energy for proton hopping and enhance rapid proton transport.As a proof of concept,the DES@ZIF-8 membrane is fabricated directly into a H_(2)/O_(2)HTPEMFC.This work provides not only a kind of efficient proton conducive electrolytes,but also theoretical support for improving proton conductivity by optimizing hydrogen-bonding networks.
基金supported by the National Natural Science Foundation of China(22075169)Shaanxi Fundamental Science Research Project for Chemistry and Biology(22JHQ026)Shaanxi University of Science and Technology。
文摘Multicomponent crystalline materials construct more complex and diversified structures with different combinations and modes,which expands the material structure space and application fields.In this work,we have successfully synthesized two twocomponent ionic hydrogen-bonded organic frameworks(iHOF-32 and iHOF-33)and a three-component iHOF(iHOF-34).Guanidine hydrochloride which is rich in N and H and has a short chain length strengthens the hydrogen bonding network of iHOF,thereby aiding in the efficient migration of protons.The rigid architecture of 1,1'-diamino-4,4'-bipyridine diiodide furnishes additional scaffolding for the iHOFs and enhances its robustness under harsh conditions.iHOF-34 accomplishes the combination of the ultra-high proton conductivity of iHOF-32 and the robustness of iHOF-33 by the synergistic interaction among the three components of ligands.In addition,iHOF-34 was fabricated as a composite membrane with a peak proton conductivity of 1.55×10^(-1)S cm^(-1),which is 3.8 times higher than that of recast Nafion,and has extensive potential in fuel cells.The self-assembly strategy of multicomponent HOFs opens up new avenues for constructing diverse structures while promising new opportunities for applications in the fields of proton conduction and energy storage.
基金supported by the Royal Society(No.RGS\R2\202203Lan_4824933)the Engineering and Physical Sciences Research Council(Nos.EP/N509577/1,EP/T517793/1,and EP/S03305X/1).
文摘Enhancing the proton conductivity of proton exchange membranes(PEMs)is essential to expand the applications of proton exchange membrane fuel cells(PEMFCs).Inspired by the proton conduction mechanism of bacteriorhodopsin,cucurbit[n]urils(CB[n],where n is the number of glycoluril units,n=6,7,or 8)are introduced into sulfonated poly(ether ether ketone)(SPEEK)matrix to fabricate hybrid PEMs,employing a nature-inspired chemical engineering(NICE)methodology.The carbonyl groups of CB[n]act as proton-conducting sites,while the host–vip interaction between CB[n]and water molecules offers extra protonconducting pathways.Additionally,the molecular size of CB[n]aids in their dispersion within the SPEEK matrix,effectively bridging the unconnected proton-conducting sulfonic group domains within the SPEEK membrane.Consequently,all hybrid membranes exhibit significantly enhanced proton conductivity.Notably,the SPEEK membrane incorporating 1 wt.%CB[8](CB[8]/SPEEK-1%)demonstrates the highest proton conductivity of 198.0 mS·cm^(−1) at 60°C and 100%relative humidity(RH),which is 228%greater than that of the pure SPEEK membrane under the same conditions.Moreover,hybrid membranes exhibit superior fuel cell performance.The CB[8]/SPEEK-1%membrane achieves a maximum power density of 214 mW·cm^(−2),representing a 140%improvement over the pure SPEEK membrane(89 mW·cm^(−2))at 50°C and 100%RH.These findings serve as a foundation for constructing continuous proton-conducting pathways within membranes by utilizing supramolecular macrocycles as fuel cell electrolytes and in other applications.
基金the state assignment on the topic“Interdisciplinary approaches to the creation and study of micro-/nanostructured systems”(No.125012200595-8)Conductivity measurements of the samples were performed in accordance with the state task for FRC PCP and MC RAS(No.124013000692-4).
文摘A series of solid solutions with high content of Tb_(2)O_(3)-(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.667-0.830)are synthesized in the Tb_(2)O_(3)-TiO_(2)system via co-precipitation and/or mechanical activation.This is followed by high-temperature annealing for 4-22 h.The X-ray diffrac-tion method showed that the fluorite structure was realized for(Tb_(x)Ti_(1−x))4O_(8−2x)(x=0.75-0.817).The solid solution Tb_(3.12)Ti_(0.88)O_(6.44)(64mol%Tb_(2)O_(3)(x=0.78))with a fluorite structure exhibited a maximum hole conductivity of~22 S/cm at 600℃.To separate the ionic component of the conductivity in the electronic conductor Tb_(3.12)Ti_(0.88)O_(6.44),its high entropy analogue,(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44),was synthesized in which all rare-earth elements(REE)cations exhibited valency of+3.Consequently,the contribution of ionic(proton)conductivity(~7×10^(−6)S/cm at 600℃)was revealed with respect to the background of dominant hole conductivity.The proton conduct-ivity of high-entropy oxide(HEО)(La_(0.2)Gd_(0.2)Tm_(0.2)Lu_(0.2)Y_(0.2))_(3.12)Ti_(0.88)O_(6.44)was confirmed by the detection of the isotope effect,where the mobility of the heavier O-D ions was lower than that of the O-H hydroxyls,resulting in lower conductivity in D_(2)O vapors when com-pared to H_(2)O.
文摘To develop proton-conducting materials with high hydrothermal and acid-base stability and to elucidate the proton-transport mechanism through visualized structural analysis,two new lanthanum phosphite-oxalates with 3D frameworks,designated as[La(HPO_(3))(C_(2)O_(4))0.5(H_(2)O)_(2)](La‑1)and(C_(6)H_(16)N_(2))(H_(3)O)[La_(2)(H_(2)PO_(3))_(3)(C_(2)O_(4))_(3)(H_(2)O)](La‑2)(C_(6)H_(14)N_(2)=cis-2,6-dimethylpiperazine),were prepared by hydrothermal and solvothermal conduction,respectively.La‑1 was constructed with lanthanum phosphite 2D layers and C_(2)O_(4)^(2-)groups,whereas La‑2 was constructed with lanthanum oxalate 2D layers and H_(2)PO^(3-)groups.Alternating current(AC)impedance spectra indicate that the pro-ton conductivities of both compounds could reach 10^(-4)S·cm^(-1)and remain highly durable at 75℃and 98%of rela-tive humidity(RH).Due to the abundance of H-bonds in La‑2,theσof La‑2 was higher than that of La‑1.La‑1 exhibited excellent water and pH stability.CCDC:2439965,La‑1;443776,La‑2.
基金financially supported by the National Natural Science Foundation of China (No. 21774006)
文摘The sulfonated poly(α-methyl styrene-b-isobutylene-b-α-methyl styrene)copolymers(S-ASIBS)with the average molar percentage of sulfonic acid(-SO_(3)H)groups(SP)ranging from 3.6 mol%to 14.3 mol%could be synthesized by sulfonation of ASIBS with acetyl sulfate.The hydrophilic ionic channels were generated for proton exchange membranes(PEMs)by ion aggregation of-SO_(3)H groups and microphase separation between hydrophobic polyisobutylene and hydrophilic sulfonated poly(α-methyl styrene)segments in S-ASIBS.The proton transport ability was improved while oxidative stability was decreased by increasing SP in S-ASIBS.The appropriate SP of about 12.7 mol%in S-ASIBS provides the available PEMs with high proton transport ability,low methanol permeability and good oxidative stability.The absence of active tertiary hydrogen atoms along S-ASIBS copolymer chains avoids their attack by peroxy radicals.The residual rates of weight(RW)and proton conductivity(Rσ)of S-ASIBS-12.7 membrane after oxidation treatment for 916 h were 84.3%and 88.1%respectively,near to those of commercial Nafion 117(RW=87.9%,Rσ=90.3%).The membrane electrode assembly(MEA)could be prepared by using various S-ASIBS as PEMs for direct methanol fuel cell.The single cell with S-ASIBS-12.7 MEA behaves high performance of open circuit voltage(OCV)of 548 mV and peak power density(Pmax)of 36.1 mW·cm^(-2),which is similar to those of Nafion 117(OCV=506 mV,P_(max)=35.6 mW·cm^(-2)).To the best of our knowledge,this is the first example of advanced S-ASIBS membrane with high proton conductivity,excellent fuel barrier property and remarkable oxidative stability for promising PEMs.
文摘Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge behind self-supporting CONs membrane lies in weak noncovalent interlayer interactions and thus loose stacking,insufficient strength and structure stabilities.Herein,we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs(CON-NH2)to negatively-charged sulfonated CONs(CON-SO_(3)H).Ultrathin and large lateral sized CON-SO_(3)H and CON-NH2 are synthesized,followed by restacking to prepare freestanding CONs membrane with CON-SO_(3)H as the membrane bulk.Benefiting from effective interlayer interconnection due to strong electrostatic interaction,the obtained CON-SO_(3)H/CON-NH2 membrane displays features of ultrahigh integrity,dense stacking,eminent water/acid/base/organic solvents stabilities and mechanical strength(109 MPa).The shortened-SO_(3)H distance contributes to construct site-continuous transfer pathways,and the deprotonated-SO_(3)H and protonated-NH2 form acid-base pairs to decrease interfacial resistance,which impart membrane superior proton conductivity of 486 mS cm^(-1)(80℃,100%RH).This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.
基金supported by the National Natural Science Foundation of China(No.22179047)the Development of Scientific and Technological Project of Jilin Province(20230201139GX).
文摘The thiol-imidazole functionalized(p-triphenyl-pentafluorobenzaldehyde)polymer(IMPTP)was prepared and quaternized with different side chains to obtain imidazolium-modified Me-IMPTP,He-IMPTP and BIM-IMPTP membranes for application in high-temperature proton exchange membrane fuel cells(HT-PEMFCs).The presence of the thioether group in the polymers enabled radical scavenging for antioxidant properties,while imidazolium cations interacted strongly with H_(2)PO_(4) to prevent phosphoric acid(PA)leaching.The prepared BIM-IMPTP membrane incorporating bisimidazolium cation string with a long alkyl spacer demonstrated the highest mass retention of 82.93%after being immersed in Fenton's reagent for 24 h.Additionally,the PA-doped BIM-IMPTP membranes exhibited excellent PA retention under high-humidity conditions(80℃/100%RH).The single cell equipped with the BIM-IMPTP/320%PA membrane achieved a maximum power density(PDmax)of 945 mW cm^(-2)at 160℃.Among the four membranes with a similar acid doping content(ADC),the BIM-IMPTP/163%PA membrane with bis-cation pairs in the side chains exhibited a well-developed microphase-separated structure and high proton conductivity(119.0 mS cm^(-1)at 180℃).The single cell assembled with BIM-IMPTP/163%PA membrane maintained a PDmax of 613 mW cm^(-2)at 160℃ and demonstrated long-term operational stability under both 150/400 mA cm^(-2)and 80℃/200 mA cm^(-2)conditions.These results indicate that the introduction of thioether and bis-cation pairs in the structural design of polymers contributes significantly to the long-term stability of HT-PEMs.
基金National Natural Science Foundation of China(Nos.92161111 and 21901038)Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,ChinaInternational Cooperation Fund of Science and Technology Commission of Shanghai Municipality,China(No.21130750100)。
文摘Highly reduced molybdenum red(MR)clusters have emerged as a new type of polyoxomolybdates(POMos)and showed great potential as electron/proton reservoirs for energy conversion and storage,as well as for catalysis.However,the limited structural diversity of MR clusters significantly hinders further exploration of their potential as functional materials.Herein,we describe the synthesis of a novel highly reduced MR cluster{Mo_(49)}(compound 1)based on rational assembly of a variety of basic building blocks(BBs).In addition to the well-established BBs found in the family of MR clusters,the unique tetrahedral{MoVI 4}BB plays a key role in directing the assembly to afford trigonal pyramid-like structure of compound 1,which consists of 49 Mo and 148 O atoms with a high reduction degree of 73%.Moreover,at 80℃and 98%relative humidity(RH),the pellet sample of compound 1 displays good proton conductivity of 7.88×10^(-3)S/cm owing to the efficient hydrogen-bonded network built from the surface oxygen atoms,protons and vip water molecules.This research offers new insights into the assembly and synthesis of MR clusters through a BB strategy and manifests their significant potential for advanced applications.
基金supported by the Natural Science Foundation of Jilin Province-Free Exploration General Project(YDZJ202201ZYTS331)the National Natural Science Foundation of China(21801038)+1 种基金the Science and Technology Research Foundation of Jilin Educational Committee(JJKH20221158KJ)the Fundamental Research Funds for the Central Universities(2412022ZD002,2412022ZD009)。
文摘Highly reduced polyoxometalates(POMs) are predicted to be used as rather high energy density materials;however,it still suffers from the limited cluster species and reduction ratio.Here we demonstrate that it is possible to employ the building block strategy to generate a highly reduced polyoxomolybdate(C_(2)H_(8)N)_(14)(NH_(4))_(4)H_(14)[Mo_(48)-ⅤMo_(26)ⅥO_(202)(OH)_(12)(SO_(4))_(6)]·46H_(2)O(Mo_(74)).The fundamental Mo-based{Mo_x}(x=4,5,and 6) building blocks,which are templated by tetra-coordinated anions{MoO_(4)}or{SO_(4)},not only lay foundation for the formation of Mo_(74) featuring an unprecedented reduction ratio of 65%,but also give rise to SBBs-mediated(secondary building blocks) supramolecular dense packing interactions among the isolated Mo_(74) clusters that are favorable for proton conduction.Remarkably,high proton conductivity(2.04×10^(-2)S cm^(-1)) had been realized at 50℃ and 90% relative humidity,revealing one of the well-known POMs-based crystalline proton conducting materials.This result highlights that this building block approach possesses great potential in producing highly reduced POM systems that can achieve controllable reduced ratio and desirable properties.
