Imidazolium functionalized block copolymer anion exchange membrane with enhanced hydroxide conductivity and alkaline stability via tailoring side chains

To develop polymer electrolyte membrane with both high hydroxide conductivity and good alkaline stability, series of poly(arylene ether sulfone)s block copolymers bearing varied imidazolium functionalized aromatic pendants are synthesized, and the relationship between ionic pendants and the membrane properties are investigated and discussed. Atomic force microscopy (AFM) results suggest that, the well-controlled block copolymers and pendent aromatic chain structures are responsible for the formation of the well-defined microphase-separated morphology which is benefit to construct highly conductive ionic transport channels in membrane. The membranes tethering longer imidazolium functionalized aromatic pendants (Im-DFDM-bPES) exhibit large hydroxide conductivity than those bearing shorter ones (Im-DFDB-bPES) in spite of their comparable IEC values, this is in accordance with their sizes of hydrophilic domains in membrane. Among the membranes, Im-DFDM-bPES-x7y32 with IEC of 1.30 mequiv g^?1 gives the highest hydroxide conductivity (34.2 and 98.7 mS cm^?1 at 25 and 80 °C, respectively). Besides, both Im-DFDM-bPES and Im-DFDB-bPES membranes exhibit high alkaline stability after aging under severe conditions (4 M NaOH at 80 °C) for 144 h, where the aged Im-DFDM-bPES and Im-DFDB-bPES give hydroxide conductivity remaining by 74.8%–77.2% and 64.5%–66.4%, mechanical properties with maximum stress of 47.36–51.30 MPa and 60.03–62.28 MPa, respectively, indicating good chemical stability of both imidazolium moiety and block copolymer backbone.     

Block copolymer anion exchange membrane containing polymer of intrinsic microporosity for fuel cell application

High hydroxide conductivity and good stability of anion exchange membranes (AEMs) is the guarantee that anion exchange membrane fuel cells (AEMFCs) yield high power output for a long time. Balanced conductivity and stability can be better guaranteed by adopting a relatively low ion exchange capacity (IEC) while reducing the ion transport resistance Herein, a novel block copolymer AEM was designed and synthesized, which contains hydrophobic polymer of intrinsic microporosity (PIM) blocks and hydrophilic, quaternized polysulfone (PSF) blocks. The PIM block imparts high free volume to the membrane so that the resistance of hydroxide ion transport can be reduced; meanwhile, the hydrophilic block can self-assemble more easily to produce a better developed hydrophilic microphase, which may function as efficient channels for hydroxide ion transport. Both transmission electron microscopy images and small-angle X-ray scattering patterns suggested that the resulting AEM possessed a microphase separated morphology. The membrane showed a conductivity of 52.6 mS cm^-l at 80 °C with a relatively low IEC of 0.91 mmol g^?1. It also exhibited a good dimensional stability, swelling ratio maintained almost constant (ca. 17%) at 25 to 80 °C. The assembled H₂/O₂ fuel cell yielded a peak power density of 270 mW cm^?2 at 560 mA cm^?2. Our work demonstrates that incorporation of PIM in an AEM by means of block polymerization is an efficient way of promoting microphase separation and facilitating ion transport.     

Fluorene-containing poly(arylene ether sulfone)s with imidazolium on flexible side chains for anion exchange membranes

Anion exchange membranes with high ionic conductivity and dimensional stability attract a lot of research interests. In present study, a series of fluorene-containing poly(arylene ether sulfone)s containing imidazolium on the flexible long side-chain are synthesized via copolycondensation, Friedel-Crafts reaction, ketone reduction, and Menshutkin reaction sequentially. The membranes used for characterization and membrane electrode assembly are obtained by solution casting and ion exchange thereafter. The morphology of the membranes is studied via transmission electron microscopy, and the microphase separation is observed. The long side-chain structure is responsible for the distinct hydrophilic-hydrophobic microphase separation, which facilitates the transport of hydroxide ions in the membranes. The incorporation of imidazolium on the flexible long side-chain is favorable for the ionic aggregation and transport in the membranes. The resulted membranes exhibit high hydroxide conductivities in the range of 48.5–83.1 mS cm⁻¹ at 80 °C. All these membranes show good dimensional stability and thermal stability. The single cell performance shows a power density of 102.3 mW cm⁻² at 60 °C using membrane electrode assembly based-on one of the synthesized polymers.     

Constructing micro-phase separation structure by multi-arm side chains to improve the property of anion exchange membrane

In order to improve the performance of anion exchange membrane (AEMs) as the core component of alkaline fuel cell, a novel pentamethyl-contained phenolphthalein multi-arm monomer is synthesized. The highly imidazolium-functionalized poly (arylene ether ketone) membrane (Im-PEK-x) are prepared by introducing 1,2-dimethylimidazole as hydrophilic segments. The monomer, polymer and anion exchange membranes are confirmed by ¹H NMR spectra. The well-defined micro-phase separated structure of membranes is conducive to ion transport and the structure is investigated by TEM and SAXS. The imidazolium-functionalized membranes (Im-PEK-0.8) exhibits high ionic conductivity (0.148 S/cm at 80 °C). The tensile strength of Im-PEK-0.8 membrane is 30.06 MPa. Furthermore, after immersing in 60 °C, 2 M NaOH solution for 240 h, the ionic conductivity remains 0.092 S/cm for Im-PEK-0.8. The 1,2-dimethylimidazole enhance alkaline stability by steric effect of the substituent group at the C2 position. All these results indicate that this is a new method to enhance conductivity and stability performance of AEMs.     

Novel multi-channel anion exchange membrane based on poly ionic liquid-impregnated cationic metal-organic frameworks

The “trade-off” effect between hydroxide conductivity and dimensional stability is challenging issue for anion exchange membrane fuel cells (AEMFCs). In this study, the framework of UiO-66-NH₂ is for the first time applied to anion exchange membranes (AEMs). The robust pore walls of UiO-66-NH₂ with mechanical and structural durabilities protect the membrane from the excessive swelling effects (a swelling ratio of 7%). In addition, the framework of UiO-66-NH₂ is directly modified into (UiO-66-NH₂)⁺Cl⁻ as hydroxide conduction channels by anion stripping for the first time. And we construct well-organized ion nanochannels by the in-situ self-assembly of N,N,N′,N' -tetramethyl-1,6-hexanediamine (TMHDA) and allyl bromide within the highly ordered pores of (UiO-66-NH₂)⁺Cl⁻. The obtained QA@(UiO-66-NH₂)⁺Cl⁻ then incorporated into pristine membrane (QAPPO) to fabricate the novel multi-channel AEMs. The hydroxide conductivity of QA@(UiO-66-NH₂)⁺Cl⁻/PPO is up to 123 mS⋅cm⁻¹ at 80 °C, which is greatly improved compared to QAPPO pristine membrane.     

Preparation and performance of bisimidazole cationic crosslinked addition-type polynorbornene-based anion exchange membrane

The late transition metal catalyst system (η³-allyl)Pd(PPh₃)Cl/Li[B(C₆F₅)₄]·2.5Et₂O (Li[FABA]) was used to catalyze 5-norbornene-2-methylenehexyl ether (NB-MHE) and 5-norbornene-2-methylene-(6-bromohexyl) ether (NB–O–Br) controllable addition copolymerization to obtain post-functionalized vinyl addition-type block copolymer aP(NB-O-Br-b-NB-MHE). 1,6-Bis(2-methylimidazole)hexane (Bis-MeIm) was used as a crosslinking agent to prepare a series of anion exchange membranes (AEMs) CL-aP(NB-O-Br-b-NB-MHE). The initial thermal decomposition temperature of the obtained addition-type polynorbornene-based AEM was about 250 °C. The AEM had moderate water uptake (WU) and swelling ratio (SR), and obvious micro-phase separation structure that could be observed from the AFM phase diagram. It could maintain high OH^? conductivity (85.07 mS cm^?1, 80 °C) and alkali resistance stability (soaking alkali for more than 500 h at 25 °C). In the single cell test of the H₂/O₂ fuel cell assembled by CL5-aP(NB-O-Br-b-NB-MHE), the peak power density was 177 mW cm^?2.     

Partially crosslinked comb-shaped PPO-based anion exchange membrane grafted with long alkyl chains: Synthesis,characterization and microbial fuel cell performance

Anion exchange membranes (AEMs) with higher ion exchange capacities (IECw) are limited to applications due to excessive swelling and higher water uptake. Crosslinked macromolecular structures have been a strategy to balance between ionic conductivity and swelling in membranes. However, highly crosslinked AEMs are usually mechanically brittle and poorer in ion transport. Thus we report a series of partially diamine crosslinked (X = 10%, 15%, 20%) comb-shaped AEMs functionalized with dimethylhexadecylammonium groups exhibiting improved flexibility, water uptake and swelling properties over conventional un-crosslinked or fully crosslinked materials. The higher conductivities in these PPO AEM(X) (for example, X = 20%, IECw = 1.96 mmol/g, σ(OH⁻) ~ 67 mS/cm at 80 °C) are attributed to the distinct nanophase separation as observed in SAXS and AFM analyses. Finally, the microbial fuel cell performances of the membranes were compared with commercially available cation and anion exchange membranes.     

Novel polymer electrolytes based on triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) with ionically active SiO2

A novel polymer electrolyte based on triblock copolymer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) with ionically active SiO₂ inclusions has been designed. The electrolyte shows favorable features for ion migration such as low glass transition temperature and high concentration of amorphous phase. Combined with the effect of active SiO₂, its ionic conductivity is about 8.0 × 10⁻⁵ S cm⁻¹ at 30 °C, which exceeds that for the PEO-based systems. As applying them to cells with LiFePO₄-type cathodes, a capacity of about 147.0 mAh g⁻¹ is obtained at 60 °C, which is retained by more than 90% after 40 charge/discharge cycles. Moreover, about 100 mAh g⁻¹ could still be delivered as temperature decreases to 30 °C.     

Novel anion exchange membrane with poly ionic liquid-confined hypercrosslinked polymer for enhanced anion conduction and stability

Hypercrosslinked polymer (HCP) holds great potential for utilization as novel anion exchange membrane (AEM) material due to their rich microporous structure and high thermal/chemical stability while remaining challenges due to lack of hydroxide carriers. Herein we report a novel strategy of fabricating poly ionic liquid (PIL)-confined HCP for ion transfer. PIL precursors are loaded into the pores of HCP and in-situ polymerized to prepare PIL@HCP, which is then incorporated into quaternized poly (2,6-dimethyl-1,4-phenylene oxide) (QAPPO) to fabricate composite membrane. The introduction of PIL provides high concentration of quaternary ammonium (QA) groups in the porous networks of HCP. And the organic components impart outstanding compatibility between PIL@HCP and QAPPO matrix. All these permit the formation of interconnected hydroxide transfer channels through the membranes. Especially, the rigid and hydrophobic HCP functions with steric hindrance effectively impedes the attack of hydroxide ions on QA groups and maintains structure stability. Accordingly, the PIL@HCP/QAPPO composite membrane with high ion exchange capacity (IEC) of 2.33 mmol g^?1 achieves a hydroxide conductivity of 98 mS cm^?1 (80 °C, 100% RH), 92% higher than that of QAPPO. Meanwhile, the area swelling degree of PIL@HCP/QAPPO reduces to 13.6% in comparison to QAPPO (25.7%) and its conductivity retains 88% after alkaline treatment.     

Hydrogen production by electrochemical methanol reformation using alkaline anion exchange membrane based cell

Electrochemical methanol reformation (ECMR) is an alternative promising technology for producing hydrogen at low energy consumption compared to water electrolysis. In this process, solid polymer electrolyte Nafion® is widely employed, due to its superior proton conductivity. However, major limitations are the utilisation of expensive platinum based catalysts, high cost of the above membrane and the crossover of methanol through the polymer electrolyte membrane. In the present work, attempt has been to made to use low cost polymer electrolyte membrane and less noble electro catalyst. A series of Anion Exchange Membranes (AEM) are synthesized from Poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) for its application in ECMR. PPO is successfully made into anion conducting by chloromethylation followed by quaternization. Two AEM's are synthesized by optimizing chloromethylation reaction time to 5 h and quaternization time to 5 and 8 h and are labelled as QPPO (C5, Q5) and QPPO (C5, Q8) respectively. Further, with the view to improve the anion conductivity further, composite AEMs are prepared by incorporating inorganic anion conducting quaternized graphene oxide particles in the matrix of PPO and QPPO (C5, Q8) polymers separately to obtain two polymers PPO/QGO and QPPO/QGO. The anionic conductivity of PPO/QGO and QPPO/QGO polymer is 1.2 × 10⁻⁴ and 1.5 × 10⁻⁴ S cm⁻¹ respectively. Both the membranes are subjected as electrolyte for ECMR application using membrane electrode assembly made by with in house synthesized nitrogen doped graphene supported Pd catalyst (Pd/NG) as anode catalyst and commercial Pt/C as cathode catalyst. The performance of composite membrane was compared with the commercial Fumasep® FAA anion exchange membrane. The polarization studies of ECMR cell with composite membrane shows comparable performance with that of commercial Fumasep® FAA-2 FAA membrane. The durability of the membrane(s) in the electrolysis environment was tested for about 20 h.     

High chemical stability anion exchange membrane based on poly(aryl piperidinium): Effect of monomer configuration on membrane properties

In recent years, ether-free polyaryl polymers prepared by superacid-catalyzed Friedel-Crafts polymerization have attracted great research interest in the development of anion exchange membranes(AEMs) due to their high alkali resistance and simple synthesis methods. However, the selection of monomers for high-performance polymer backbone and the relationship between polymer structure construction and properties need further investigated. Herein, a series of free-ether poly(aryl piperidinium) (PAP) with different polymer backbone steric construction were synthesized as stable anion exchange membranes. Meta-terphenyl, p-terphenyl and diphenyl-terphenyl copolymer were chosen as monomers to regulate the spatial arrangement of the polymer backbone, which tethered with stable piperidinium cation to improve the chemical stability. In addition, a multi-cation crosslinking strategy has been applied to improve ion conductivity and mechanical stability of AEMs, and further compared with the performance of uncrosslinked AEMs. The properties of the resulting AEMs were investigated and correlated with their polymer structure. In particular, m-terphenyl based AEMs exhibited better dimensional stability and the highest hydroxide conductivity of 144.2 mS/cm at 80 °C than other membranes, which can be attributed to their advantages of polymer backbone arrangement. Furthermore, the hydroxide conductivity of the prepared AEMs remains 80%–90% after treated by 2 M NaOH for 1600 h, exhibiting excellent alkaline stability. The single cell test of m-PTP-20Q4 exhibits a maximum power density of 239 mW/cm² at 80 °C. Hence, the results may guide the selection of polymer monomers to improve performance and alkaline durability for anion exchange membranes.     

Preparation and characterization of organic-inorganic hybrid anion exchange membrane based on crown ether functionalized mesoporous SBA-NH2

In this paper, self-made diformyl-dibenzo-18-crown-6 ether (DDB₁₈C₆) is in-situ grafted into the pores of mesoporous molecular sieve (SBA-NH₂), and then the aforementioned modified molecular sieve (SBA-C) is introduced into the polyvinyl alcohol solution, and then the glutaraldehyde as the crosslinking agent to synthesized the anion exchange membrane under for fuel cell application. During the experiment, a series of anion exchange membranes (P-(SBA_x%-C), x is the mass fraction of SBA-NH₂) is developed and the pore channels and chemical structures of the aforementioned membrane is verified by FT-IR, SAXD, N₂ adsorption-desorption, ¹H NMR and XPS. Moreover, the performance of the membrane synthesized in this paper is also investigated and the results revealed that the unique membrane internal structure can improve the OH^? transportation efficiency. Furthermore, the ionic conductivity of P-(SBA_10%-C) membrane is the highest (0.107S·cm^?1) and the power density is the highest (354.8 mW cm^?2) at 80 °C. By immersing P-(SBA_10%-C) membrane in 6 mol L^?1 KOH solution for 168 h, the conductivity at 80 °C only decreased by 2%, proving that P-(SBA_10%-C) has a higher conductivity, good single cell performance and alkali stability.     

Anion exchange membranes based on poly (ether ether ketone) containing N-spirocyclic quaternary ammonium cations in phenyl side chain

It was reported that the existence of N-spirocyclic quaternary ammonium (QA) cation could improve alkaline stability of anion exchange membrane materials (AEM). Therefore, the cyclo-quaternization reaction with pyrrolidine (Pyr) and piperidine (Pip) was carried out to prepare quaternized poly (ether ether ketone)s bearing five-membered and six-membered N-spirocyclic quaternary ammonium (QA) groups in the phenyl side chains (QPEEK-spiro-pyr and QPEEK-spiro-pip), respectively. From the transmission electron microscope, the hydrophilic-hydrophobic phase-separated morphology was formed in QPEEK-spiro membranes after incorporating N-spirocyclic QA cations and bulky spacer simultaneously in the phenyl side chain. The effect of N-spirocyclic QA groups on performance of resulted AEMs was then studied in detail. The anion conductivities of QPEEK-spiro-pyr and QPEEK-spiro-pip in OH^? form at 80 °C were 49.6 and 30.9 S cm^?1, respectively. The remaining proportions of hydroxide conductivity for QPEEK-spiro-pyr and QPEEK-spiro-pip membranes after immersing in 1 M NaOH at 60 °C were 81.0% and 74.7%, respectively, which were higher than that of 62.3% for QPEEK-TMA containing conventional QA groups in the phenyl side chain. Fuel cell assembled with QPEEK-spiro-pyr achieves a peak power density of 90 mW cm^?2. These results indicate the strategy of simultaneously introducing N-spirocyclic QA cations and bulky spacers can improve the performance of AEM to a certain extent. There are some other factors that influence the alkaline stability of the prepared AEMs, such as the existence of ether bonds in the main chain. However, this work still provides a valuable reference towards the molecular design of AEMs with improved performance.     

Enhanced ionic conductivity of anion exchange membranes by grafting flexible ionic strings on multiblock copolymers

A new strategy to prepare high-conductivity anion exchange membranes (AEMs) is presented here. A series of phenolphthalein-based poly(arylene ether sulfone nitrile) multiblock AEMs has been synthesized by selectively grafting flexible ionic strings on hydrophilic segments to form ionic regions. Moreover, the phenolphthalein groups are introduced to force chains apart and create additional interchain spacing. In addition, the nitrile groups suspended on main chains are aimed at enhancing the anti-swelling behavior of as-prepared AEMs. Along these processes, well-defined phase separation has been attained, forming excellent ion-transport channels. The effective phase separation has been confirmed by atomic force microscopy. Finally, as-prepared AEMs exhibit a high hydroxide conductivity, ranging from 40.1 to 121.6 mS cm⁻¹ in the temperature range of 30–80 °C, and superior ionic conductivity to IEC ratio at 80 °C. Furthermore, excellent thermal stability and desirable mechanical strength have been rendered by as-prepared AEMs. However, the alkaline stability of as-prepared AEMs requires further optimization.     

The effect of side chain length on the morphology and transport properties of fluorene-based anion exchange membranes

Poly[(fluorene alkylene)- co(biphenyl alkylene)] (PFBA) compounds with quaternary ammonium (QA) groups (PFBA-nC-QAs) that are linked with side chains of various lengths (n = 1～6 carbon atoms) are designed and synthesized by a superacid catalysis reaction, which has the advantages of low cost, easy synthesis and mild reaction conditions. The correlative properties of PFBA-nC-QAs, including water uptake, thermal stability, morphology, ion conductivity and alkaline stability, are discussed in detail. The side chain length is vital to the morphology and transport performance of PFBA-nC-QAs. As the side chain length increases, the alkaline stability and hydroxide ion conductivity of the prepared membranes improve with decreasing water uptake. Experimental results indicate that the hydroxide conductivity of PFBA-6C-QA is 154 mS cm^?1 at 80 °C. Moreover, no degradation of functional groups of PFBA-6C-QA is observed during 30 days of immersion in 2 M NaOH at 80 °C. The peak power density of PFBA-6C-QA is 278 mW cm^?2 at 60 °C with a hydrogen/air single fuel cell. By controlling the length of the polymer side chain, the method is simple and effective for building anion exchange membranes with high performance.     

A novel anion exchange membrane based on poly (2,6-dimethyl-1,4-phenylene oxide) with excellent alkaline stability for AEMFC

We report a novel comb-shaped anion exchange membrane based on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) and 4-(dimethylamino)butyraldehyde diethyl acetal (DABDA). The Menshutkin reaction successfully introduced DABDA into the brominated PPO backbone, which was proved through FT-IR and ¹H NMR. The distinct hydrophilic/hydrophobic microphase separation structure observed by transmission electron microscope (TEM). As the increase of grafting degree, so does the water uptake, swelling ratio, hydroxide conductivity and alkaline stability. The membranes also possess good mechanical property with tensile strength from 14.2 to 38.11 MPa. This is due to the increasing number of hydroxide and unique steric hindrance effect caused the higher water uptake and higher dimensional stability. Simultaneously, especially PPO/DABDA-60 in comb-shaped membranes demonstrate an excellent long-term alkali resistance stability. In a 576-h alkali resistance stability test, the retained ionic conductivity of the PPO/DABDA-60 membrane is 96% of the initial value. The PPO/DABDA-60 is a potential candidate material for AEM.     

Degradation prediction model for proton exchange membrane fuel cells based on long short-term memory neural network and Savitzky-Golay filter

Proton exchange membrane fuel cell (PEMFC) as a promising green power source, can be applied to vehicles, ships, and buildings. However, the lifetime of the fuel cell needs to be prolonged in order to achieve a wide range of applications. Consequently, the prediction of the health state draws attention lately and is critical to improving the reliability of the fuel cell. Since the degradation mechanism of the fuel cell is not fully understood, the data-driven method is very suitable for designing degradation prediction models. However, the data-driven method usually requires a lot of data, which is difficult to be obtained. To solve the issues, we propose a degradation prediction model for PEMFC based on long short-term memory neural network (LSTM) and Savitzky-Golay filter in this paper. First, we select the monitoring parameters for building the degradation prediction model by analyzing the degradation phenomenon of the fuel cell. Then, Savitzky-Golay filter is utilized to smooth out the selected data, and the sliding time window is used to generate training samples. Finally, the LSTM is applied to establish the degradation prediction model. Moreover, the dropout layer and mini-batch method are adopted to improve the model generalization ability. We use an actual aging data of the fuel cell to verified the proposed degradation prediction model. The results demonstrate that the proposed model can precisely predict the fuel cell degradation. It is worth mentioning that the determination coefficient (R²) of the test set based on the model trained by 25% of data is 0.9065.     

Ag nanoparticles on mesoporous carbon support as cathode catalyst for anion exchange membrane fuel cell

Silver nanocatalyst (40 wt%) is deposited on commercial mesoporous carbon support material (Ag/C) using two different wet chemical methods, to obtain high electrochemically active surface area. The catalyst materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetric analysis and are evaluated toward the oxygen reduction reaction (ORR) in alkaline media employing the rotating disk electrode method. It is worth noting that the Ag/C leads to oxygen reduction through a direct four-electron pathway in alkaline medium. The silver catalyst on mesoporous carbon exhibits relatively higher mass activity for ORR (38 A g⁻¹) compared to that with Vulcan carbon (32 A g⁻¹) at −0.2 V vs SCE at room temperature. Anion exchange membrane fuel cell shows maximum power density of 310 mW cm⁻² with Ag/C cathode catalyst using H₂ and O₂ gases at 65% RH conditions at 65 °C.     

Electrochemical and fuel cell evaluation of Co based catalyst for oxygen reduction in anion exchange polymer membrane fuel cells

Co based catalyst were evaluated for oxygen reduction (ORR) in liquid KOH and alkaline anion exchange membrane fuel cells (AAEMFCs). In liquid KOH solution the catalyst exhibited good performance with an onset potential 120 mV more negative than platinum and a Tafel slope of ca. 120 mV dec⁻¹. The hydrogen peroxide generated, increased from 5 to 50% as the electrode potential decreased from 175 to −300 mV vs. SHE.In an AAEMFC environment, one catalyst (GP2) showed promising performance for ORR, i.e. at 50 mA cm⁻² the differences in cell potential between the stable performance for platinum (more positive) and cobalt cathodes with air and oxygen, were only 45 and 67 mV respectively. The second catalyst (GP4) achieved the same stable power density as with platinum, of 200 and 145 mW cm⁻², with air at 1 bar (gauge) pressure and air (atm) cathode feed (60 °C), respectively. However the efficiency was lower (i.e. cell voltage was lower) i.e. 40% in comparison to platinum 47.5%.     

Novel single-layer gas diffusion layer based on PTFE/carbon black composite for proton exchange membrane fuel cell

A series of poly(tetrafluoroethylene)/carbon black composite-based single-layer gas diffusion layers (PTFE/CB-GDLs) for proton exchange membrane fuel cell (PEMFC) was successfully prepared from carbon black and un-sintered PTFE, which included powder resin and colloidal dispersion, by a simple inexpensive method. The scanning electron micrographs of PTFE/CB-GDLs indicated that the PTFE resins were homogeneously dispersed in the carbon black matrix and showed a microporous layer (MPL)-like structure. The as-prepared PTFE/CB-GDLs exhibited good mechanical property, high gas permeability, and sufficient water repellency. The best current density obtained from the PEMFC with the single-layer PTFE/CB-GDL was 1.27 and 0.42 A cm⁻² for H₂/O₂ and H₂/air system, respectively.