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Extra water- and acid-stable MOF-801 with high proton conductivity and its composite membrane for proton exchange membrane Jin Zhang, Huijuan Bai, Qiu Ren, Hong-Bin Luo, Xiaoming Ren, Zheng-Fang Tian, and Shanfu Lu ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b09070 • Publication Date (Web): 02 Aug 2018 Downloaded from http://pubs.acs.org on August 4, 2018

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ACS Applied Materials & Interfaces

Extra water- and acid-stable MOF-801 with high proton conductivity and its composite membrane for proton exchange membrane

Jin Zhang,a,c,† Hui-Juan Bai,b,† Qiu Ren,a,c Hong-Bin Luo,a,c Xiao-Ming Ren*a,c, Zheng-Fang Tian,d Shanfu Lu*b

a

State Key Laboratory of Materials-Oriented Chemical Engineering and College of

Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 210009, P. R. China b

Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of

Chemistry and Environment, Beihang University, Beijing, 100191, P. R. China. c

College of Materials Science and Engineering, Nanjing Tech University, Nanjing

210009, P. R. China d

Hubei Key Laboratory for Processing and Application of Catalytic Materials,

Huanggang Normal University, Huanggang 438000, P. R. China †

These authors contributed equally to this work.

Fax: 86-25-58139481 Tel: 86-25-58139476 E-mail: [email protected] (XMR); [email protected] (SFL)

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Abstract Proton exchange membranes (PEMs), characterized by selectively permitting the transfer of proton and acting as separator in electrochemical devices, have attracted immense attention. The composite membrane, fabricated from organic polymer matrix and high proton-conducting MOF, integrates the excellent physical and chemical perfomances of the polymer and MOF, achieving collective properties for good-performance PEMs. In this study, we demonstrate that MOF-801 shows remarkable proton conductance with σ = 1.88×10-3 S cm-1 at 298 K and 98%RH, specifically, together with extra stability to hydrochloric acid or diluting sodium hydroxide aqueous solution, and boiling water. Furthermore, the composite membranes (denoted as MOF-801@PP-X, where X represents the mass percentage of MOF-801 in the membrane) have been fabricated using the sub-micrometer scale crystalline particles of MOF-801 and blending PVDF-PVP matrix, and these PEMs display high proton conductivity, with σ = 1.84×10-3 S cm-1 at 325 K 98%RH. A composite membrane as PEM was assembled into H2/O2 fuel cell for tests, indicating that these membrane materials have vast potential on PEMs application for electrochemical devices.

Keywords: Metal-organic frameworks; MOF-polymer composite membrane; proton exchange membrane; chemical stability; proton conductivity

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Introduction Proton exchange membranes (PEMs) are characterized by selectively permitting the transfer of proton and acting as separator in a range of electrochemical devices, e.g., electrochemical reactors, fuel cells, electrochromic displays and electrochemical sensors,1-3 thereby it is of interest from the viewpoint of both fundamental and applied researches to explore new applicable PEMs. The most commonly used PEM is Nafion membranes, which shows tremendous proton conductance (σ = 10−1−10−2 S cm−1) in 60−80 °C and 98%RH, however, confront with great challenges during the large scale realistic application, resulting from low thermal stability, hazardous manufacturing process and high cost.4,5 To date, these inherent flaws have not been settled yet. It is crucial to seek for potential alternative membranes that accompany with (1) good proton conductance (σ > 1.0×10−4 S cm−1), (2) excellently thermal stability and chemical stability in the acid and water environment, (3) good mechanical performance, (4) low-cost production and simplistic processes of preparation.6-8 In response, enormous studies are devoting to develop new types of PEMs, examples include modified Nafion, various polymer, and composite membranes.9-17 In recent years, a new type of crystalline porous materials, called as metal−organic frameworks (MOFs) or porous coordination polymers and featured with structure designability and pore size tunability, have attracted much attention and achieved great progress in proton conduction.18-29 Hitherto, thanks to the extensively study by researchers, some of proton conducting MOFs show much high proton conductivity, which reaches up to 10−2 S cm−1,30-32 even 1.82 S cm−1 (at 70 °C and under 90%RH),33 nonetheless most of them have poor chemical stability ascribe to the coordination bonding construction characteristic between metal ion and ligand, and consequently hamper their realistic application in PEMs. In this regard, it is of great significance to explore excellent chemical stable MOFs with high proton conductivity for technique application.34-36 Noticeably, most of proton conducting MOFs reported were studied on the pellets or single crystal of the materials, which are not directly usable as the electrolyte membrane in electrochemical devices. Thereby considering 3



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the practical application of proton conducting MOFs in electrochemical devices, it is necessary to make them as a membrane. Recent studies by us37,38 and other groups39-41 have demonstrated that the composite membrane of MOF with organic polymer integrates the exceptional chemical and physical properties of polymer and proton-conducting MOF, and may achieve collective properties to fabricate high-performance PEMs. Poly(vinylidene fluoride) (PVDF) shows outstanding chemical and thermal stabilities, high mechanical strength, together with the features of low cost and favoring to form membrane, leading to it being one of the most widely used membrane materials in industry.42-44 However, the hydrophobic nature of PVDF appears to major obstacle for PEMs application under high relative humidity owing to the poor proton conductance, and several examples validate that composite membranes based on PVDF matrix display considerable proton conductivity only when soaked in water.37,45 While, Polyvinylpyrrolidone (PVP) is a typical hydrophilic polymer, and the hydrophilic PVP as the matrix can effectively improve water-assisted proton transport performance of the composite membrane. Furthermore, the N-heterocycle of PVP affords to accept protons from acid, suggesting that PVP has the vast potential for PEMs application,39,46 since Zhu et al. reported the first study on polymer composite PEMs of MOF with PVP.38 In this context, a series of blended polymer membranes comprised of PVP and other polymers show high proton conductivity and excellent performance in PEMs application.7,

47,48

Hence, if the

sub-micrometer scale high proton-conducting MOF particles are integrated into the blending PVDF-PVP matrix to fabricate composite membrane, and this will bring together the best of individual component, achieving high proton conductance and excellent thermal and chemical stabilities. In this paper, we demonstrate high performance proton-conducting MOF-801, with steeply uptaking water vapor at low relative pressure and the remarkable proton conductivity of 1.88×10-3 S cm-1 at 298 K and 98%RH. Particularly, MOF-801 shows excellent chemical stability in hydrochloric acid or diluting sodium hydroxide 4


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aqueous solutions, and boiling water. The membranes have been facilely prepared with the sub-micrometer scale crystalline particles of MOF-801 and blending PVDF-PVP matrix, and the PEMs prepared display high proton conductance (1.84×10-3 S cm-1) at 325 K 98%RH, and as an illustration of concept application, the composite membranes as PEM were further assembled into H2/O2 fuel cell for tests, and the results suggest these membrane materials have vast potential on PEMs application for electrochemical devices. Results and discussion Crystal structure of MOF-801 The crystal structure of MOF-801 was previously reported.49 For the convenience of better understanding the proton conductance, we describe simply the crystal structure of MOF-801 again. This MOF crystallizes in cubic space group Pn-3, and the zirconium(IV) ion shows tetragonal antiprism coordination geometry with eight oxygen atoms (Fig. S1a). The three-dimensional framework of MOF-801 is built from the zirconium-oxide secondary building unit (SBUs) with linear and ditopic linkers of fumarate. As shown in Fig. S1b, a zirconium-oxide SBU consists of six crystallographically equivalent zirconium ions, which are connected together through eight µ3-oxygen atoms, amongst them, four hydroxyl (OH) groups and four O2- ions. Each of SBUs is coordinated to 12 fumarates and each of fumarates is coordinated to two SBUs to build a three-dimensional framework, which has a network of porous tetrahedral and octahedral cages (ref. Fig. S1c, 1d and Fig. 2). The internal pore diameters in framework were of 7.4 Å, 5.6 Å and 4.8 Å, respectively, calculated using Platon program.49 Synthesis, chemical- and thermal-stability of MOF-801 The sub-micrometer scale microcrystals of MOF-801 were achieved via a slight modification of the methodology previously reported.49 The sub-micrometer scale crystalline sample was obtained. TEM photos of the sample of MOF-801 display that 5



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the microcrystals aggregate together and a single particle have a sub-micrometer scale (ref. Fig. S3), which consists of the analysis from Laser Particle Size measurement (ref. Fig. S4). The sub-micrometer scale microcrystalline sample was also characterized by IR spectrum (Fig. S5), XPS for C1s, N1s, O1s and Zr3d core levels (ref. Fig. S6 and S7) and thermogrametric (TG) technique (ref. Fig. S8a), respectively. The sample phase purity was examined through Powder X-ray Diffraction (PXRD) technique. As shown in Fig. 1, the experimental PXRD profile of MOF-801 is well agreement with the simulated pattern of MOF-801, which is obtained from the single-crystal structure data using the program of Mercury3.1, indicating that the microcrystalline sample of MOF-801 has high phase purity. To inspect the stability of MOF-801 in water, the microcrystalline samples of MOF-801 had been immersed in water at ambient temperature for 3 days and boiling water for 12 h as well, respectively, as depicted in Fig. 1 and Fig. S8b, and the PXRD patterns of the samples soaked in cooling or boiling water are nearly identical to that of as-synthesized sample of MOF-801, demonstrating that MOF-801 possesses extra stability to water. The samples of MOF-801 had also been soaked in hydrochloric acid (6.0 mol/L) and diluting sodium hydroxide (0.1 mol/L) aqueous solutions for 3 days, respectively. As shown in Fig. 1, their PXRD patterns indicated that MOF-801 exhibits excellently acidic and diluting basic stability. It is worth mentioning that, up to date, only few numbers of proton conducting MOFs with good stability in both acidic and alkali circumstances. The PXRD profile of the sample used for the impedance test demonstrates that the structure of MOF-801 was maintained although it shows slight poor crystallinity regarding the as-synthesized sample. Furthermore, the variable temperature PXRD patterns indicate that MOF-801 preserves its structural integrity up to 250 °C at least (ref. Fig. S9). The excellent chemical and thermal stabilities render MOF-801 to have the practical applicability in the field of proton conduction.

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Fig. 1 PXRD profiles of MOF-801 samples immersed in boiling water or DMF, HCl (6 mol/L) or NaOH (0.1 mol/L) aqueous solutions, after used for AC impendence measurement, the as-prepared and the simulated PXRD pattern, respectively. Proton conductance of MOF-801 The impedance measurement was performed on the compressed pellet of microcrystalline sample for assessing the proton conductivity of MOF-801, and the frequency spans from 102 to 106 Hz, and the temperature ranges from 289 to 334 K at 98% relative humidity (RH) in the measurements. All the Nyquist plots at different temperatures shown in Fig. 2a display high similarity, which is comprised of imperfect arc at the high frequency and tail at the low frequency. In general, both bulk and grain boundary conduction might be expected. In this study, In the high frequency region, the Nyquist plots performed with an imperfect arc rather than two separated arcs, indicating the proton transfer in bulk and grain boundary is difficult to separate from each other, because the value of time constant τ of the two components are comparable, and the analogous behaviors have been well elucidated in other proton conducting materials.50-52 Noteworthily, this MOF exhibits much higher proton conductance with σ = 1.19×10-3 S cm-1 at lower temperature (289 K) and 98%RH. As depicted in Fig. 2b, the proton conductivity of MOF-801 is increased with elevating temperature, and σ = 2.12×10-3 S cm-1 at 302 K, which is higher than the proton conductivity of well-studied proton-conducting MOFs, e.g. PCMOF-5 (1.3×10-3 S cm-1 at 295 K and 98%RH),53 UiO-66(Zr)-(COOH)2 (0.85×10-3 S cm-1 at 298 K and 95%RH),32 (NH4)2[MnCr2(ox)6]3·4H2O (1.1×10-3 S cm-1 at 295 K a1nd 96%RH),54 7



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and comparable to some efficient proton conducting materials of Cd-5TIA (3.61×10-3 S cm-1 at 301 K and 98%RH),55 MOF-808 (2.65×10-3 S cm-1 at 290 K and 98% RH),37 (NH4)2(adp)[Zn2(ox)3]·3H2O (8×10-3 S cm-1 at 298 K and 98%RH).56 At 334 K and 98%RH, the maximum value of 4.16×10-3 S cm-1 has been obtained, which is nearly more than fourfold of the proton conductivity at 289 K. This remarkable proton conductivity value at 334 K is competable with that of high proton conductivity water-assisted proton conducting materials, such as UiO-66(Zr)(COOH)2 (2.3×10-3 S cm-1 at 363 K and 95%RH),32 Zr2(PO4)H5(L)2·H2O (1×10-3 S cm-1 at 413 K and 96%RH).57 Furthermore, the time-dependent impedance was investigated in the period of eight days at room temperature and 98%RH, and the measurement was performed every other day. As depicted in Fig. S12, the impedance spectra obtained in different times show no significant change, indicating that MOF-801 possesses long-term proton-conducting stability. The proton transport activation energy was determined by means of the Arrhenius equation (1),

ln(σT ) = ln A −

Ea k BT

(1)

where the symbols σ, A, Ea and kB represent the proton conductivity, the pre-exponential factor, the proton-transport activation energy and Boltzmann constant, respectively. The Arrhenius plot of MOF-801 is plotted in Fig. 2c, which is linearly approximated in the temperature ranges of 289-334 K. The activation energy value was estimated as 0.256 eV, which lies in the range of Ea < 0.4 eV and corresponds to the typical Grotthuss mechanism.58 On the basis of the crystal structure analysis,49 the H-bonds form among the coordinated water molecules, OH groups in the Zr6O4(OH)4 SBUs and the coordinated COO- groups on the surface of the cavities. Besides this, the water molecules at low uptake mainly reside in in the tetrahedral cavities and form the H-bonds between water molecules in the cavities as well as between the OH groups in the Zr6O4(OH)4 SBUs and the water molecules in the cavities, whereas the 8


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water molecules at high uptake occupy both two types of tetrahedral and octahedral cavities, and the H-bonds connect the water molecules in the tetrahedral and octahedral cavities and the OH groups in the Zr6O4(OH)4 SBUs. Obviously, the water molecules absorbed conduce to form well-established hydrogen-bonding network in the framework of MOF-801, the hopping process of protons could be realized by proton transfer in the H-bond networks of …Zr6O4(OH)4…(H2O)n… or/and derived from the coordinated carboxylate groups and OH groups in Zr6O4(OH)4 SBUs, and this proton-hopping process is similar to that observed in other hydrated proton conductors.32, 59

(b)

(a)

(c)

(d)

Fig. 2 (a) Nyquist plots of MOF-801 at selected temperatures and 98% RH (b, c) plots of σ vs. T and ln(σT) vs. 1000/T for MOF-801 (d) water vapor adsorption isotherms (298 K) of MOF-801. Filled and open symbols correspond to adsorption and desorption processes, respectively. To take a closer investigation of the relationship between the relative humidity and proton conductivity in the MOF, the humidity-dependent proton conductivity has been measured at 298 K, as shown in Fig. S13, the proton conductivity of MOF-801 9



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is rapidly increased with increasing relative humidity in the ranges of 43-98%RH. The conductivity is found to be 1.92×10-7 S cm-1 at 43% RH, 1.64×10-5 S cm-1 at 75% RH, and the maximum value is 1.88×10-3 S cm-1 at 98%RH. The highly humidity-dependent conductance indicates that the water molecules in cages of MOF-801 framework play a crucial role in proton conduction for MOF-801, which is because that the water molecules absorbed in octahedral and tetrahedral cavities of the framework are favorable to generating well-established hydrogen-bonding networks, and these hydrogen-bonding networks as effective pathways would give rise to MOF-801 showing higher proton conductivity under high relative humidity. This observation is also agreed well with the aforementioned Grotthuss mechanism with participation of water molecules. At the lower relative humidity, the insufficient hydrogen-bonding networks, formed between the small amount of water molecules in the framework and the Zr6O4(OH)4 clusters, could not provide an efficient proton-hopping pathway, thus resulting in poor proton conductivity, while, the amount of adsorbed water in the framework increases with the relative humidity, and thus, more efficient hydrogen-bonding networks of …Zr6O4(OH)4…(H2O)n… would be generated in high relative humidity, and achieving high proton conductivity. The water adsorption profile of MOF-801 shows that the amount of water adsorbed increases with the rising relative pressure of water vapor (ref. Fig. 2d), implying that the MOF-801 is capable of adsorbing water at lower relative humidity. Additionally, the proton conductance of MOF-801 under anhydrous condition has also been measured, as shown in Fig. S14, the MOF-801 exhibits negligible proton conductivity. This

finding

implies

that

the

protons

hop

in

the

H-bond

networks

of …Zr6O4(OH)4…(H2O)n…, but not the surface of the cavities. Preparation and characterization of membranes MOF-801@PP-X In terms of excellent stability and high proton conductivity, and as a step toward the realistic application, we have successfully fabricated mixed matrix membranes (MMMs) in which the microcrystalline powders of MOF-801 as filler dispersed in blending PVP-PVDF supporting matrix. Here the composite membranes were denoted 10


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as MOF-801@PP-X, where X is the mass percentage of MOF-801 (X%) in MOF-801@PP-X and X = 0, 20, 40, 60, respectively. The PXRD patterns of composite membranes MOF-801@PP-X together with the as-synthesized MOF-801 are illustrated in Fig. 3, all membranes show MOF-801 characteristic diffractions, and the relative intensities of MOF-801 diffractions gradually enhanced with increasing its relative amount in the membranes, demonstrating that the crystalline structure of MOF-801 is maintained without any change in the supporting matrix. The morphology and cross section of each composite membrane was characterized by scanning electron microscopy (SEM), and the corresponding SEM images are shown in Fig. 4 and Fig. S16, the microcrystals of MOF-801 are evenly mixed and distributed in the membranes, and this can be further validated by the energy-dispersive X-ray spectroscopy (EDS). The elemental mapping shows the oxygen and zirconium elements homogeneously distributed in the membranes (ref. Fig. S17). Besides, with increasing content of MOF-801 in the composite membranes, the microcrystals of MOF-801 are more closely spaced and the surface roughness of composite membrane increases. Interestingly, the flexibility of composite membrane speedily increases when it was exposed to the high relative humidity (98%RH) environment and this is because that PVP access to absorb water from the high relative humidity environment, resulting in the increase of flexibility of the membranes.

Fig. 3 PXRD profiles of the as-synthesized MOF-801 and the membranes of MOF-801@PP-X (X = 0, 20, 40 and 60, respectively). 11



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(b)

(a)

(c)

(d)

Fig. 4 (a) SEM image of MOF-801@PP-60 and the elemental mapping images for (b) F, (c) O, (d) Zr in MOF-801@PP-60. Proton conductance of composite membranes MOF-801@PP-X The proton conductivity of membranes MOF-801@PP-X were evaluated by impedance spectra, and the membranes were exposed in the 98%RH environment and temperature range of 289-334 K during the measurement. The representative Nyquist plots are displayed in Fig. S20 and the proton conductivities have been obtained. As depicted in Fig. 5 and Fig. S 20h, all the membranes display increased proton conductivity with elevating temperature, with temperature increasing from 289K to 321K, the proton conductivity increases from 8.20×10-6 and 4.35×10-5 to 3.13×10-5 and 2.43×10-4 S cm-1 for MOF-801@PP-20 and MOF-801@PP-40, respectively. As for MOF-801@PP-60, the proton conductivity σ = 9.05×10-4 S cm-1 at 289K, and the maximum of 1.84×10-3 S cm-1 is achieved at 325 K. while, the bare composite membrane MOF-801@PP-0 shows much lower proton conductance (4.46×10-6 S cm-1) at 298K in contrast with that of MOF-801 incorporated membranes. Apparently, 12


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the proton conductivity increases with rising mass percentage of MOF-801 in a membrane, and this observation demonstrates that MOF-801 improves directly the proton transport performance of membranes because of its high intrinsic proton conductance.

Fig. 5 ln(σT) vs. 1000/T plots of membranes MOF-801@PP-X (X = 0, 20, 40 and 60). PEMFC performance of composite membranes The high proton conductivity of the membranes encourages us to examine their single fuel cell performance. The composite membrane MOF-801@PP-60 was chosen as the representative to fabricate a membrane electrode assembly. As depicted in Fig. 6a, the open circuit voltage (OCV) is 0.95 V at 303 K and 100%RH, which is comparable to that obtained in other composite membranes reported, such as CS/H3PO4@MIL-101-6 (0.91V), CS/S-MIL-101-6 (0.91 V), CS/H2SO4@-MIL-101-8 (0.95 V),60 and less than Nafion based membranes (1.01 V).61 Additionally, the open circuit voltage is no clear change after the membrane electrode assembly worked for twenty-six hours. Meanwhile, as displayed in Fig. 6b, the MOF-801@PP-60-based MEA shows the maximum power density of 2.2 mW cm-2 at 4.53 mA cm-2, which means that the membrane is promising on PEMs application for electrochemical devices.

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(a)

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(b)

Fig. 6 (a) Plot of open-circuit voltage versus time (b) Polarization and power density curves of MOF-801@PP-60 at 303 K and 100%RH. Conclusion In summary, the thorough investigation disclosed that MOF-801 shows impressive proton conductivity of 1.88×10-3 S cm-1 at 298 K and 98%RH, and ultra-stability to hydrochloric acid or sodium hydroxide aqueous solutions, and boiling water. These excellence performances in both proton conductance and stability are better than that of many up to date proton conducting MOFs recently reported. As a significant step toward the practical application in PEMs, the membranes were facilely and successfully fabricated using the sub-micrometer scale crystalline particles of MOF-801 with blending PVDF-PVP matrix, and the studies demonstrated that the composite membrane MOF-801@PP-60 shows much high proton conductance with σ = 1.84×10-3 S cm-1 at 325 K and 98%RH, together with great potentially applicable as PEMs. Our study gives rise to a fresh impetus for the practical application of proton conducting MOFs composite materials as PEMs in electrochemical devices. Experimental section Materials and reagents Solvents and chemicals used in this study are analytical grade and without further purification. 14


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Preparation of MOF-801. The sub-micrometer scale microcrystals of MOF-801 were harvested following a slightly modifying procedure published in the literature.49 Fumaric acid (1 mmol, 116 mg), ZrOCl2·8H2O (1 mmol, 322 mg) and the solvent of DMF/formic acid (4 mL/1.4 mL) were mixed and stirred at ambient temperature, then the mixture was transferred to a 10 mL Teflon-lined autoclave, kept at 130 ℃ for 6 h. White precipitate of MOF-801 was achieved when the Teflon-lined autoclave was cooled down to ambient temperature. The precipitate was separated by suction, washed with deionized water for 3 times (10 mL each time), and finally dried at 80 ℃ under vacuum for 24 h for all measurements. Yield: ca. 68% calculated according to the reactant of fumaric acid. Elemental microanalysis calculated for [Zr6O4(OH)4(fumarate)6](DMF)1.9(H2O)22: C, 18.79; H, 3.89; N, 1.40. Found: C, 18.83; H, 3.42; N, 1.47. Preparation of composite membranes. In this study, the composite membrane (MOF-801@PP-X) was fabricated by a slurry casting method. The sub-micrometer scale microcrystals of MOF-801 were mixed with PVP (70wt%) and PVDF (30wt%) for the corresponding composite membrane, and the amount of MOF-801 is 20, 40 and 60wt% in each membrane. A similar procedure was utilized for all composite membranes preparation, and the typical process is described here for the preparation process of membrane with 20wt% of MOF-801, and the sample is labeled as MOF-801@PP-20. MOF-801 microcrystals (100 mg) were sonically dispersed in DMF (3 mL) for 1 h to produce a suspension solution, and PVP/PVDF powders (280 mg/120 mg) were added to the suspension solution, and the mixture was stirred at room temperature for 4 h to give a homogeneous jelly. Such homogeneous jelly was poured onto a glass slide, which is dried under vacuum at 70 ℃ for 2 h for removing DMF. The solidified membrane was removed from the slide and washed with deionized water for three times (10 mL/time), and dried in air for all kinds of measurements. General Methods. Elemental analyses were performed for C, H, and N using an 15



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Elementar Vario EL III analytical instrument. PXRD data were collected on a Bruker D8 diffractometer, operated at 40 kV and 40 mA, with Cu Kα radiation (λ = 1.5418 Å) in the range of 2θ = 5−50° with 0.01° per step. TG analysis was carried out using a TA2000/2960 instrument from 20 to 800 °C in N2 atmosphere. The morphologies of sub-micrometer scale crystals MOF-801, and the composite membranes were investigated using Hitachi S-3400 field emission SEM and JEM-2800. The proton conductivity at a certain humidity was measured using CHI 660D electrochemical workstation with conventional three-electrode method, and the alternating current frequency spans from 100 Hz to 1 MHz with 5 mV signal amplitude. The proton conductivity in the anhydrous environment was evaluated by impedance measurements under N2 atmosphere, which were collected using Concept 80 system, and the frequency ranges from 1 Hz to 10 MHz. The membrane electrode assembly (abbr. MEA) was finally prepared by cold pressing the electrodes using a 4.0 cm2 (2.0 cm×2.0 cm) membrane and then fixed the sample between two graphite plates with parallel gas flow channels. The Pt loaded on both cathode and anode is of 0.5 mg cm-2, respectively. Fuel cell test system was operated 30 ℃ with humidified H2 and O2 fed into the cell at the flow rate of 100 and 200 mL min-1, respectively. The single cell was firstly activated via constant voltage charge-discharge for 1 h to ensure the fuel cell performance reaching the steady state. Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: Tetragonal-antiprismatic coordination geometry of ZrO8, octahedral SBU of Zr6O4(OH)4(COO)12, octahedral cage, tetrahedral cage in crystal structure of MOF-801, Packing diagram showing octahedral and tetrahedral cages in MOF-801 viewed along direction, TEM photos of the as-synthesized sample of MOF-801, Particle size distribution of MOF-801 obtained using Laser Particle Size Analyzer, IR spectrum of as-synthesized sample of MOF-801, XPS spectrum of MOF-801, XPS spectra of C1s, N1s, O1s and Zr3d in MOF-801, TG curve of 16


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MOF-801, PXRD patterns of the samples as-synthesized and soaked in DMF for 3 days together with the simulated pattern of MOF-801, Variable temperature PXRD patterns of MOF-801 in 30-190 °C and 30-400 °C, PXRD patterns of MOF-801 before and after treatment with 0.1 M H3PO4, NaOH 0.2 M and HCl 6 M, Nyquist plots of MOF-801 at 298 K with different relative humidity and humidity-dependent proton conductivity at 298 K, Circle fitting of MOF-801 at 298 K, Time-dependent Nyquist plots of MOF-801 at room temperature and 98% RH, Nyquist plots of MOF-801 at selected temperatures under anhydrous conditions, Optical images of MOF-801@PP-X (X = 0, 20, 40, 60), SEM images of surface morphology and cross section of membrane MOF-801@PP-X (X = 0, 20, 40 and 60), SEM images of 1@PP-60 and the elemental mapping images of C, F, O, Zr in MOF-801@PP-60, TG plots of MOF-801@PP-X (X = 0, 20, 40 and 60), Swelling ratio of MOF-801@PP-X (X = 0, 20, 40 and 60) at 30 °C, H2 crossover current density of MOF-801@PP-60 composite membrane at 303 K and at 100% RH, Current density at a constant cell voltage of 0.60 V at 303 K and at 100% RH for 1440 minutes in single cell, The stress-strain curves of MOF-801@PP-X (X = 40 and 60) composite membrane, Nyquist plots of MOF-801@PP-X (X = 0, 20, 40 and 60) at 98% RH at selected temperatures, Plots of lg(σ) versus T of composite membranes MOF-801@PP-X (X = 0, 20, 40 and 60) (PDF). Acknowledgment The authors are thankful for the support of the Priority Academic Program Development of Jiangsu Higher Education Institutions, the National Nature Science Foundation of China (21671100), and the Postgraduate Research & Practice Innovation Program of Jiangsu Province ( KYCX17_0930).

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References 1.

Kreuer, K. D. Proton Conductivity: Materials and Applications. Chem. Mater. 1996, 8, 610−641.

2.

Kreuer, K. D.; Paddison, S. J.; Spohr, E.; Schuster, M. Transport in Proton Conductors for Fuel-Cell Applications: Simulations, Elementary Reactions, and Phenomenology. Chem. Rev. 2004, 104, 4637−4678.

3.

Alberti, G.; Casciola, M. Solid State Protonic Conductors, Present Main Applications and Future Prospects. Solid State Ionics 2001, 145, 3−16.

4.

Paddison, S. J. Proton Conduction Mechanisms at Low Degrees of Hydration in Sulfonic Acid−Based Polymer Electrolyte Membranes. Annu. Rev. Mater. Res. 2003, 33, 289−319.

5.

Mauritz, K. A.; Moore, R. B. State of Understanding of Nafion. Chem. Rev. 2004, 104, 4535−4586.

6.

Peighambardoust, S. J.; Rowshanzamir, S.; Amjadi, M. Review of the Proton Exchange Membranes for Fuel Cell Applications. Int. J. Hydrogen Energy 2010, 35, 9349-9384.

7.

Guo, Z.; Xu, X.; Xiang, Y.; Lu, S.; Jiang, S. P. New Anhydrous Proton Exchange Membranes for High-Temperature Fuel Cells Based on PVDF–PVP Blended Polymers. J. Mater. Chem. A 2015, 3, 148-155.

8.

de Bruijn, F. A.; Dam, V. A. T.; Janssen, G. J. M. Review: Durability and Degradation Issues of PEM Fuel Cell Components. Fuel Cells 2008, 8, 3-22.

9.

Li, Q.; He,R.; Jensen, J. O.; Bjerrum, N. J. Approaches and Recent Development of Polymer Electrolyte Membranes for Fuel Cells Operating above 100 °C. Chem. Mater. 2003, 15, 4896-4915.

10. Laberty-Robert, C.; Valle, K.; Pereira, F.; Sanchez, C. Design and Properties of 18


Page 19 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Functional Hybrid Organic-Inorganic Membranes for Fuel Cells. Chem. Soc. Rev. 2011, 40, 961-1005. 11. Kim, Y.; Ketpang, K.; Jaritphun, S.; Park, J. S.; Shanmugam, S. A Polyoxometalate Coupled Graphene Oxide–Nafion Composite Membrane for Fuel Cells Operating at Low Relative Humidity. J. Mater. Chem. A 2015, 3, 8148-8155. 12. Kang, D. W.; Song, J. H.; Lee, K. J.; Lee, H. G.; Kim, J. E.; Lee, H. Y.; Kim, J. Y.; Hong, C. S. A Conductive Porous Organic Polymer with Superprotonic Conductivity of a Nafion-Type Electrolyte. J. Mater. Chem. A 2017, 5, 17492-17498. 13. Patel, H. A.; Mansor, N.; Gadipelli, S.; Brett, D. J.; Guo, Z. Superacidity in Nafion/MOF Hybrid Membranes Retains Water at Low Humidity to Enhance Proton Conduction for Fuel Cells. ACS Appl. Mater. Interfaces 2016, 8, 30687-30691. 14. Sun,

H.;

Tang,

B.;

Wu,

P.

Two-Dimensional

Zeolitic

Imidazolate

Framework/Carbon Nanotube Hybrid Networks Modified Proton Exchange Membranes for Improving Transport Properties. ACS Appl. Mater. Interfaces 2017, 9, 35075-35085. 15. Lin, B.; Cheng, S.; Qiu, L.; Yan, F.; Shang, S.; Lu, J. Protic Ionic Liquid-Based Hybrid Proton-Conducting Membranes for Anhydrous Proton Exchange Membrane Application. Chem. Mater. 2010, 22, 1807-1813. 16. Yan, F.; Yu, S.; Zhang, X.; Qiu, L.; Chu, F.; You, J.; Lu, J. Enhanced Proton Conduction in Polymer Electrolyte Membranes as Synthesized by Polymerization of Protic Ionic Liquid-Based Microemulsions. Chem. Mater. 2009, 21, 1480−1484. 17. Chen, P.; Hao, L.; Wu, W.; Li, Y.; Wang, J. Polymer-Inorganic Hybrid Proton Conductive Membranes: Effect of the Interfacial Transfer Pathways. Electrochim. 19



Page 20 of 26

Acta 2016, 212, 426-439. 18. Gui, D.; Dai, X.; Tao, Z.; Zheng,T.; Wang, X.; Silver, M. A.; Shu, J.; Chen, L.; Wang, Y.; Zhang, T.; Xie, J; Zou, L; Xia, Y.; Zhang, J; Zhao, L.; Diwu, J.; Zhou, R.; Chai, Z.; Wang, S. Unique Proton Transportation Pathway in a Robust Inorganic Coordination Polymer Leading to Intrinsically High and Sustainable Anhydrous Proton Conductivity. J. Am. Chem. Soc. 2018, 140, 6146-6155. 19. Meng, X.; Wang, H. N.; Song, S. Y.; Zhang, H. J. Proton-Conducting Crystalline Porous Materials. Chem. Soc. Rev. 2017, 46, 464-480. 20. Li, A.-L.; Gao, Q.; Xu, J.; Bu, X.-H. Proton-Conductive Metal-Organic Frameworks: Recent Advances and Perspectives. Coord. Chem. Rev. 2017, 344, 54-82. 21. Dong, X. Y.; Hu, X. P.; Yao, H. C.; Zang, S. Q.; Hou, H. W.; Mak, T. C. Alkaline

Earth

Metal

(Mg,

Sr,

Ba)-Organic

Frameworks

Based

on

2,2',6,6'-Tetracarboxybiphenyl for Proton Conduction. Inorg. Chem. 2014, 53, 12050-12057. 22. Li, J.; Cao, X. L.; Cao, Y. Y.; Zhang S. R.; Du, D. Y.; Qin, J. S.; Li, S. L.; Su, Z. M.; Lan, Y. Q. The Enhancement on Proton Conductivity of Stable Polyoxometalate-Based Coordination Polymers by the Synergistic Effect of Multiproton Units. Chem. Eur. J. 2016, 22, 9299-9304. 23. Zhang, F. M.; Dong, L. Z.; Qin, J. S.; Guan, W.; Liu, J.; Li, S. L.; Lu, M.; Lan, Y. Q.; Su, Z. M.; Zhou, H. C. Effect of Imidazole Arrangements on Proton-Conductivity in Metal-Organic Frameworks. J. Am. Chem. Soc. 2017, 139, 6183-6189. 24. Qin, L.; Yu, Y. Z.; Liao, P. Q.; Xue, W.; Zheng, Z.; Chen, X. M.; Zheng, Y. Z. A "Molecular Water Pipe": A Giant Tubular Cluster {Dy72} Exhibits Fast Proton Transport and Slow Magnetic Relaxation. Adv. Mater. 2016, 28, 10772-10779. 20


Page 21 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


25. Wei, Y. S.; Hu, X. P.; Han, Z.; Dong, X. Y.; Zang, S. Q. Mak, T. C. Unique Proton Dynamics in an Efficient MOF-Based Proton Conductor. J. Am. Chem. Soc. 2017, 139, 3505-3512. 26. Luo, H. B.; Ren, L. T.; Ning, W. H.; Liu, S. X.; Liu, J. L.; Ren, X. M. Robust Crystalline Hybrid Solid with Multiple Channels Showing High Anhydrous Proton Conductivity and a Wide Performance Temperature Range. Adv. Mater. 2016, 28, 1663-1667. 27. Bao, S.-S.; Shimizu, G. K. H.; Zheng, L.-M. Proton Conductive Metal Phosphonate

Frameworks.

Coordin.

Chem.

Rev.

2017.

DOI:

10.1016/j.ccr.2017.11.029. 28. Luo, H. B.; Wang, M.; Zhang, J.; Tian, Z. F.; Zou, Y.; Ren, X. M. Open-Framework Chalcogenide Showing Both Intrinsic Anhydrous and Water-Assisted High Proton Conductivity. ACS Appl. Mater. Interfaces 2018, 10, 2619-2627. 29. Kim, S.; Joarder, B.; Hurd, J. A.; Zhang, J.; Dawson, K. W.; Gelfand, B. S.; Wong, N. E.; Shimizu, G. K. H. Achieving Superprotonic Conduction in Metal-Organic Frameworks through Iterative Design Advances. J. Am. Chem. Soc. 2018, 140, 1077-1082. 30. Ramaswamy, P.; Wong, N. E.; Gelfand, B. S.; Shimizu, G. K. A Water Stable Magnesium MOF That Conducts Protons over 10-2 S cm-1. J. Am. Chem. Soc. 2015, 137, 7640-7643. 31. Zhai, Q. G.; Mao, C.; Zhao, X.; Lin, Q.; Bu, F.; Chen, X.; Bu, X.; Feng, P. Cooperative Crystallization of Heterometallic Indium-Chromium Metal-Organic Polyhedra and Their Fast Proton Conductivity. Angew. Chem. Int. Ed. 2015, 54, 7886-7890. 32. Phang, W. J.; Jo, H.; Lee, W. R.; Song, J. H.; Yoo, K.; Kim, B.; Hong, C. S. Superprotonic Conductivity of a UiO-66 Framework Functionalized with 21



Page 22 of 26

Sulfonic Acid Groups by Facile Postsynthetic Oxidation. Angew. Chem. Int. Ed. 2015, 54, 5142-5146. 33. Li, X.-M.; Dong, L.-Z.; Li, S.-L.; Xu, G.; Liu, J.; Zhang, F.-M.; Lu, L.-S.; Lan, Y.-Q.

Synergistic

Conductivity

Effect

in

a

Proton

Sources-Coupled

Metal–Organic Framework. ACS Energy Lett. 2017, 2, 2313-2318. 34. Wu, H.; Yang, F.; Lv, X.-L.; Wang, B.; Zhang, Y.-Z.; Zhao, M.-J.; Li, J.-R. A Stable

Porphyrinic

Metal–Organic

Framework

Pore-Functionalized

by

High-Density Carboxylic Groups for Proton Conduction. J. Mater. Chem. A 2017, 5, 14525-14529. 35. Ramaswamy, P.; Wong, N. E.; Shimizu, G. K. MOFs as Proton ConductorsChallenges and Opportunities. Chem. Soc. Rev. 2014, 43, 5913-5932. 36. Zhao, X.; Mao, C.; Bu, X.; Feng, P. Direct Observation of Two Types of Proton Conduction Tunnels Coexisting in a New Porous Indium–Organic Framework. Chem. Mater. 2014, 26, 2492-2495. 37. Luo, H. B.; Wang, M.; Liu, S. X.; Xue, C.; Tian, Z. F.; Zou, Y.; Ren, X. M. Proton Conductance of a Superior Water-Stable Metal-Organic Framework and Its Composite Membrane with Poly(vinylidene fluoride). Inorg. Chem. 2017, 56, 4169-4175. 38. Wang, M.; Luo, H. B.; Zhang, J.; Liu, S. X.; Xue, C.; Zou, Y.; Ren, X. M. An Open-Framework Manganese(II) Phosphite and Its Composite Membranes with Polyvinylidene Fluoride Exhibiting Intrinsic Water-Assisted Proton Conductance. Dalton Trans. 2017, 46, 7904-7910. 39. Liang, X.; Zhang, F.; Feng, W.; Zou, X.; Zhao, C.; Na, H.; Liu, C.; Sun, F.; Zhu, G. From Metal–Organic Framework (MOF) to MOF–Polymer Composite Membrane: Enhancement of Low-Humidity Proton Conductivity. Chem. Sci. 2013, 4, 983-992. 22


Page 23 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


40. Yang, L.; Tang, B.; Wu, P. Metal–Organic Framework–Graphene Oxide Composites: a Facile Method to Highly Improve the Proton Conductivity of PEMs Operated Under Low Humidity. J. Mater. Chem. A 2015, 3, 15838-15842. 41. Wu, B.; Lin, X.; Ge, L.; Wu, L.; Xu, T. A Novel Route for Preparing Highly Proton Conductive Membrane Materials with Metal-Organic Frameworks. Chem. Commun. 2013, 49, 143-145. 42. Liu, F.; Hashim, N. A.; Liu, Y.; Abed, M. R. M.; Li, K. Progress in the Production and Modification of PVDF Membranes. J. Membr. Sci. 2011, 375, 1-27. 43. Qing, G.; Kikuchi, R.; Takagaki, A.; Sugawara, T.; Oyama, S. T. CsH2PO4/Polyvinylidene Fluoride Composite Electrolytes for Intermediate Temperature Fuel Cells. J. Electrochem. Soc. 2014, 161, F451-F457. 44. Thanganathan, U.; Nogami, M. Effects of SiO2 and P2O5 on Structural, Thermal and Conductivity Properties of Inorganic Materials Doped with PVDF. RSC Adv. 2012, 2, 9596. 45. Peng, Y.; Xu, G.; Hu, Z.; Cheng, Y.; Chi, C.; Yuan, D.; Cheng, H.; Zhao, D. Mechanoassisted Synthesis of Sulfonated Covalent Organic Frameworks with High Intrinsic Proton Conductivity. ACS Appl. Mater. Interfaces 2016, 8, 18505-18512. 46. Wu, C.; Lu, S.; Wang, H.; Xu, X.; Peng, S.; Tan, Q.; Xiang, Y. A Novel Polysulfone–Polyvinylpyrrolidone Membrane with Superior Proton-to-Vanadium Ion Selectivity for Vanadium Redox Flow Batteries. J. Mater. Chem. A 2016, 4, 1174-1179. 47. Lu, S.; Xu, X.; Zhang, J.; Peng, S.; Liang, D.; Wang, H.; Xiang, Y. A Self-Anchored Phosphotungstic Acid Hybrid Proton Exchange Membrane Achieved via One-Step Synthesis. Adv. Energy Mater. 2014, 4, 1400842. 48. Xu, X.; Wang, H.; Lu, S.; Peng, S.; Xiang, Y. A Phosphotungstic Acid 23



Page 24 of 26

Self-Anchored Hybrid Proton Exchange Membrane for Direct Methanol Fuel Cells. RSC Adv. 2016, 6, 43049-43055. 49. Furukawa, H.; Gandara, F.; Zhang, Y. B.; Jiang, J.; Queen, W. L.; Hudson, M. R.; Yaghi, O. M. Water Adsorption in Porous Metal-Organic Frameworks and Related Materials. J. Am. Chem. Soc. 2014, 136, 4369-4381. 50. Liu, S.; Yue, Z.; Liu, Y. Incorporation of Imidazole within the Metal-Organic Framework UiO-67 for Enhanced Anhydrous Proton Conductivity. Dalton Trans 2015, 44, 12976-12980. 51. Stankiewicz, J.; Tomás, M.; Dobrinovitch, I. T.; Forcén-Vázquez, E.; Falvello, L. R. Proton Conduction in a Nonporous One Dimensional Coordination Polymer. Chem. Mater. 2014, 26, 5282-5287. 52. Umeyama, D.; Horike, S.; Inukai, M.; Itakura, T.; Kitagawa, S. Inherent Proton Conduction in a 2D Coordination Framework. J. Am. Chem. Soc. 2012, 134, 12780-12785. 53. Taylor, J. M.; Dawson, K. W.; Shimizu, G. K. A Water-Stable Metal-Organic Framework with Highly Acidic Pores for Proton-Conducting Applications. J. Am. Chem. Soc. 2013, 135, 1193-1196. 54. Pardo, E.; Train, C.; Gontard, G.; Boubekeur, K.; Fabelo, O.; Liu, H.; Dkhil, B.; Lloret, F.; Nakagawa, K.; Tokoro, H.; Ohkoshi, S.; Verdaguer, M. High Proton Conduction in a Chiral Ferromagnetic Metal-Organic Quartz-Like Framework. J. Am. Chem. Soc. 2011, 133, 15328-15331. 55. Panda, T.; Kundu, T.; Banerjee, R. Self-Assembled One Dimensional Functionalized Metal-Organic Nanotubes (MONTs) for Proton Conduction. Chem. Commun. 2012, 48, 5464-5466. 56. Sadakiyo, M.; Yamada, T.; Kitagawa, H. Rational Designs for Highly Proton-Conductive Metal-Organic Frameworks. J. Am. Chem. Soc. 2009, 131, 24


Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


9906-9907. 57. Donnadio, A.; Nocchetti, M.; Costantino, F.; Taddei, M.; Casciola, M.; da Silva Lisboa, F.; Vivani, R. A Layered Mixed Zirconium Phosphate/Phosphonate with Cxposed Carboxylic and Phosphonic Groups: X-ray Powder Structure and Proton Conductivity Properties. Inorg. Chem. 2014, 53, 13220-13226. 58. Xu, G.; Otsubo, K.; Yamada, T.; Sakaida, S.; Kitagawa, H. Superprotonic Conductivity in a Highly Oriented Crystalline Metal-Organic Framework Nanofilm. J. Am. Chem. Soc. 2013, 135, 7438-7441. 59. Yamada, T.; Sadakiyo, M.; Kitagawa, H. High Proton Conductivity of One-Dimensional Ferrous Oxalate Dihydrate. J. Am. Chem. Soc. 2009, 131, 3144-3145. 60. Dong, X.-Y.; Li, J.-J.; Han, Z.; Duan, P.-G.; Li, L.-K.; Zang, S.-Q. Tuning the Functional Substituent Group and Guest of Metal–Organic Frameworks in Hybrid Membranes for Improved Interface Compatibility and Proton Conduction. J. Mater. Chem. A 2017, 5, 3464-3474. 61. Zhang, J.; Tang, Y.; Song, C.; Zhang, J.; Wang, H. PEM Fuel Cell Open Circuit Voltage (OCV) in the Temperature Range of 23 °C to 120 °C. J. Power Sources 2006, 163, 532-537.

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TOC

MOF-801 shows remarkable room-temperature proton conductivity, together with extra stability to hydrochloric acid or diluting sodium hydroxide aqueous solutions, and boiling water. Moreover, its composite membranes with blending PVDF-PVP matrix display great potential for PEMs application.

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Extra water- and acid-stable MOF-801 with high ... - ACS Publications

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