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Proton conductors play a significant role in various fields, and recent research has focused on exploring crystalline porous materials for their favourable proton-transport properties. However, synthesizing these materials often poses challenges, especially in achieving crystallinity. In this study, we have successfully developed an innovative approach by constructing an amorphous microporous polymer (AMP) structure. Unlike traditional methods that require crystallization, our AMP maintains a certain pore space, while avoiding the need for strict crystallinity. Remarkably, this newly developed AMP displays high-density sulphonic acid sites on its skeleton, enabling it to function as an efficient proton conductor across a wide range of relative humidity (RH) levels. At 70°C and 100% RH, it achieves an impressive maximum conductivity value of 3.34 × 10−3 S cm−1. Such an excellent performance can be attributed to the low activation energy for proton conduction, measuring a mere 0.266 eV. This signifies a Grotthuss mechanism, indicating that protons readily jump along hydrogen bonds within the material. [ABSTRACT FROM AUTHOR]

Impedance spectroscopy was used to study proton conductivity changing of pre-dried sulfonated perfluorinated and hydrocarbon (polynaphtoleimide) membranes over time during their hydration. For this purpose, commercial perfluorinated membranes Nafion 212, Nafion 211, Gore 18 and hydrocarbon co-polynaphthoyleneimide (co-PNIS) membranes with different hydrophobicity blocks (ODAS/MDAC and ODAS/MDOT) synthesized in this work were used. It was found that the proton conductivity steady state values of Gore 18 membrane were established faster in humidity atmosphere after its drying than for other membranes studied in this work. This membrane demonstrates also better characteristics with cyclic humidity changes from 35 to 75% (sorption) and from 75 to 35% (desorption), which actually simulates start operation of PEMFC after its storage at the normal conditions. It was found that Nafion type membranes possess more universal hydration characteristics PEMFC in whole investigated humidity values interval and reveal consistently both high proton transport values and proton conductivity recovery kinetics parameters from dry state. However, the proton conductivity highest level at RH > 75% is demonstrated by fluorine-free co-PNIS membranes, which is also associated with its higher hydration degree compared to perfluorinated analogues. Moreover, it has been observed that the hydrocarbon co-PNIS (ODAS/MDOT) membrane, with a large difference in the hydrophobicity degree between polymer blocks is characterized by both higher protonic conductivity and its recovery kinetics parameters compared to the hydrocarbon analogue co-PNIS (ODAS/MDAC). The effect of the hydrophobic block on proton transport in co-PNIS membrane is discussed. [ABSTRACT FROM AUTHOR]

The current challenge with sulfonated aromatic polymer proton exchange membranes (PEMs) lies in their inability to enhance proton conductivity, mechanical strength and methanol resistance concurrently. To address this issue, a novel approach has been taken by synthesizing hydrophobic polysulfone grafted with hydrophilic sulfonated polyvinyl alcohol (PSU-g-SPVA) through Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization. This graft polymer is then utilized as a modified material for PEMs in direct methanol fuel cells (DMFCs). The morphology of phase separation within the Nafion matrix is significantly influenced by the proportion of PSU-g-SPVA. Notably, the Nafion/PSU-g-SPVA-40 modified demonstrates superior alcohol resistance, with a methanol permeability rate of 2.32 × 10−7 cm2/s. Furthermore, due to its outstanding proton conductivity, the proton selectivity of this modified membrane is an impressive 10.9 × 104 S s/cm3, which significantly surpasses that of the standard Nafion membrane at 2.82 × 104 S s/cm3. Grafting techniques of hydrophobic main chain and hydrophilic side chains open up a new method for the blending of polymers with huge polarity differences. [ABSTRACT FROM AUTHOR]

The electrochemical potential on the thylakoid membrane and its components in cotyledons of 4-, 7- and 11-day-old Hordeum vulgare L. sprouts was studied using differential absorption spectroscopy and the electrochromic shift of pigment absorption. It was found that the proton motive force decreased and the proportion of its electrical component increased during the ontogenesis of the cotyledon. Exposure to elevated temperature (40°C for 3 h) decreased the electrochemical potential, proton gradient, and thylakoid membrane conductivity for protons and increased the electrical potential on the thylakoid membrane in young 4-day-old sprouts. No significant changes in the formation of the electrochemical potential on the thylakoid membrane were detected in 7-day-old leaves, which had a fully formed photosynthetic apparatus, after heat treatment at 40°C for 3 h. A thermally induced decrease in the electrical component of the proton motive force and an increase in the transthylakoid proton gradient were detected in the senescent cotyledon of 11-day-old sprouts. It was concluded that the electrochemical potential of thylakoid membranes reacts differently to heat effects in Hordeum vulgare L. sprouts of different ages. [ABSTRACT FROM AUTHOR]

Highlights: The effects of the size structure and stability of metal–organic frameworks (MOFs) on proton conduction are comprehensively summarized. Advanced strategies for constructing proton conduction MOFs are critically discussed. Challenges and opportunities for the development of novel proton-conducting MOFs are further outlined. Proton-conducting materials have attracted considerable interest because of their extensive application in energy storage and conversion devices. Among them, metal–organic frameworks (MOFs) present tremendous development potential and possibilities for constructing novel advanced proton conductors due to their special advantages in crystallinity, designability, and porosity. In particular, several special design strategies for the structure of MOFs have opened new doors for the advancement of MOF proton conductors, such as charged network construction, ligand functionalization, metal-center manipulation, defective engineering, guest molecule incorporation, and pore-space manipulation. With the implementation of these strategies, proton-conducting MOFs have developed significantly and profoundly within the last decade. Therefore, in this review, we critically discuss and analyze the fundamental principles, design strategies, and implementation methods targeted at improving the proton conductivity of MOFs through representative examples. Besides, the structural features, the proton conduction mechanism and the behavior of MOFs are discussed thoroughly and meticulously. Future endeavors are also proposed to address the challenges of proton-conducting MOFs in practical research. We sincerely expect that this review will bring guidance and inspiration for the design of proton-conducting MOFs and further motivate the research enthusiasm for novel proton-conducting materials. [ABSTRACT FROM AUTHOR]

The design and development of cost-effective and increased methanol permeable and proton-conductive membranes are critical concerns in the fabrication of polymeric electrolyte membranes (PEM). A solution-casting process was used to create a low-cost PEM based on sulfonated polyvinyl chloride (SPVC)-Polymethyl methacrylate (PMMA) blended with varying concentrations of Poly(sodium 4-styrenesulfonate) (PSS). The contact angle, oxidative stability, swelling ratio, water uptake, and methanol uptake of SPVC/PMMA/PSS membranes were investigated as a function of PSS molar ratio. FT-IR examination, 1H NMR spectra, Raman spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), and scanning electron microscope micrographs were additionally utilized for confirming the chemical structure, morphology, and thermal stability of SPVC/PMMA/PSS membranes. Furthermore, the ion exchange capacity (IEC), proton conductivity, and methanol permeability of SPVC/PMMA/PSS membranes were investigated depending on the PSS concentration. The results showed a significant increase in proton conductivity from 1.80 × 10–2 for SPVC/PMMA/1%PSS to 4.7 × 10–2 S/cm for SPVC/PMMA/5%PSS at ambient temperature. On the other hand, the methanol permeability (P = 8.53 × 10–8 cm2/s) was noticeably lower than that of Nafion 117 (3.39 × 10–6 cm2/s). Additionally, the IEC of the manufactured membrane was 1.38 ± 0.7 meq g−1 for SPVC/PMMA/5%PSS compared to 0.91 meq g−1 for Nafion 117 membranes. The maximum water uptake of the synthesized membranes was 48.37 ± 2.27%, whereas Nafion 117 membrane absorption was 65.44%. According to conductivity studies and the membrane efficiency factor, the ideal PSS content in a polymer matrix is 4 wt.%. Finally, the developed SPVC/PMMA/PSS polyelectrolytic membranes show improvements in essential properties such as methanol permeability, proton conductivity, and IEC when combined with low-cost materials, making them an attractive contender as PEM for DMFCs. [ABSTRACT FROM AUTHOR]

The molecular motion of imidazole (Im) in proton-conducting polyacrylic acid (PAA)/Im composite materials (PAA/xIm, where x represents the number of moles of Im per mole of the carboxyl group of PAA) was investigated using solid-state 2H NMR. For the 2H NMR analysis of polymers in which multiple constituents with different kinetic states coexist, we propose the simultaneous analysis of two 2H NMR spectra observed by the quadruple echo method using different echo intervals. The 2H NMR spectra were analyzed by superimposing simulated spectra with different jumping rates of 180° flip and isotropic rotation of Im. For PAA/0.5Im-d3, Im undergoes 180° flip below 343 K and isotropic rotation above 363 K. For PAA/1.0Im-d3, Im undergoes 180° flip below 323 K and isotropic rotation above 363 K. In the temperature range of 333–343 K, Im undergoing 180° flip and isotropic rotation coexist in PAA/1.0Im-d3. The distributions of the jumping rates of 180° flip and isotropic rotation of Im were obtained. The increase in the amount of Im enhances the jumping rate of the isotropic rotation of Im and the proton conductivity of PAA/xIm at high temperatures. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) crystals have attracted strong interest as a new class of proton-conducting materials that can block atoms, molecules and ions while allowing proton transport through the atomically thin basal planes. Although 2D materials exhibit this perfect selectivity, the reported proton conductivities have been relatively low. Here we show that vacancy-rich titania monolayers are highly permeable to protons while remaining impermeable to helium with proton conductivity exceeding 100 S cm−2 at 200 °C and surpassing targets set by industry roadmaps. The fast and selective proton transport is attributed to an extremely high density of titanium-atom vacancies (one per square nm), which effectively turns titania monolayers into angstrom-scale sieves. Our findings highlight the potential of 2D oxides as membrane materials for hydrogen-based technologies. This study shows that vacancy-rich titania monolayers are highly permeable to protons while remaining impermeable to helium with proton conductivity exceeding 100 S cm−2 at 200 °C and surpassing targets set by industry roadmaps. [ABSTRACT FROM AUTHOR]

Extending the operation of proton exchange membrane fuel cells (PEMFCs) at high temperature (i.e., 120 °C) and/or low relative humidity (< 50% RH) remains a significant challenge due to dehydration and subsequent performance failure of the Nafion electrolyte. We approached this problem by integrating the Nafion matrix with a novel hybrid nanofiller, created through direct growth of TiO2 nanoparticles on the surface of carbon nanotubes. This synthetic approach allowed to preserve an effective nanodispersion of Titania particles in the hosting matrix, thereby boosting dimensional stability, hydrophilicity, and physiochemical properties of the Nafion/MWCNTs-TiO2 (NMT-x) nanocomposites compared to parental Nafion. At optimal concentration (i.e., 3 wt% with respect to the polymer), the nanocomposite membrane exhibited high transport characteristics with impressive water retention capabilities, resulting in a proton conductivity of 8.3 mS cm− 1 at 80 °C and 20% RH. The Titania nanoparticles plays a key role in retaining water molecules even under dehydrating conditions, while also directly contributing to proton transport. Additionally, the long carbon nanotubes promote the formation of additional paths for proton conductivity. These combined features enabled the NMT-3 membrane to achieve a maximum power output of 307.7 mW/cm2 in a single H2/air fuel cell (5 cm2 active electrode area and 0.5 mg Pt/cm2 at both electrodes) under very challenging conditions, specifically at 120 °C and 30% RH. This represents a significant advancement towards overcoming the limitations of traditional Nafion membranes and opens up new possibilities for high-temperature, low-humidity H2/air fuel cell applications. [ABSTRACT FROM AUTHOR]

Sulfonated poly (ether ether ketone) (SPEEK) has received substantial attention for its potential to improve the electrochemical behavior and thermomechanical capabilities of direct methanol fuel cells. This study examines how the integration by solution casting of microcrystalline cellulose (MCC) and 2,3-dialdehyde cellulose (DAC) onto highly sulfonated PEEK (with a sulfonation degree of 80%) affects its physicochemical properties and morphological structures. The mechanical attributes and proton conductivity of the polymer matrix are impacted by MCC and DAC inclusion into SPEEK membrane. The maximum proton conductivity was seen in the SPEEK/MCC membranes at 70 °C (up to 0.1 S cm−1). The proton conductivity in methanol vapor was increased by SPEEK/DAC membranes at high temperatures as opposed to pristine SPEEK and SPEEK/MCC membranes. [ABSTRACT FROM AUTHOR]

Four alkaline earth metal-based compounds were synthesized under hydrothermal conditions, using BPTC (benzophenone-3,3′,4,4′-tetracarboxylate) as ligand, and are hereinafter referred to as M-BPTC (M = Mg, Ca, Sr, Ba). These compounds exhibit interesting structural diversity, variable chemical and thermal stability, as well as antimicrobial activity and proton conductivity. The Ca-BPTC (C17H13O12Ca) belongs to the triclinic crystal system, P-1 space group (a = 6.9330 Å, b = 9.8359 Å, c = 14.8717 Å, α = 78.351°, β = 81.043°, γ = 71.696°). The Sr-BPTC (C17H10O11Sr2) crystallized into an orthorhombic crystal system, Pbca space group (a = 6.9945 Å, b = 10.3767 Å, c = 47.882 Å and α = β = γ = 90°) and showed proton conduction up to 55 °C. The compound Ba-BPTC (C17H8O10Ba2) belongs to the triclinic crystal system, P-1 space group (a = 4.39030 Å, b = 11.9969 Å, c = 16.0108 Å, α = 71.6830°, β = 86.2360°, γ = 89.790°). The crystal structure of the compound of Mg2+ with BPTC was not elucidated. The calcium coordination polymer and magnesium compound showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa and antifungal activity against Candida albicans. [ABSTRACT FROM AUTHOR]

A polymer nanocomposite based on sulfonated polyphenylene oxide with amino-functionalized mesoporous silica was designed, synthesized, and tested as a new material for proton exchange membrane (PEM preparation. Characterization of the intermediate and final products of synthesis was realized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and thermal analysis. Broadband Dielectric Spectroscopy (BDS) was used to determine dielectric properties including ionic conductivity. Thermogravimetric analysis has provided important information regarding the composition and thermal stability of the three compounds, subject to thermal degradation: 1) the amino-silica with cetyltrimethylammonium bromide (CTAB) template inside the pores (MS-NH2I), 2) the mesoporous amino-silica after removing the template (MS-NH2II) and 3) the polymer nanocomposite (sPPO-MS-NH2). The thermal decomposition of the composite samples occurs in three stages: in the first, up to 150 °C, water and organic solvents were lost; the second stage, between 200-300 °C, was due to breaking the organic functionalities (-NH2, amino and -SO3H, sulfonic acid), and the third stage, above 400 °C was due to polymer chain degradation. The final residue at 700 °C reflects the contribution of inorganic silica. The proton conductivity, for polymeric (sPPO) and composite (sPPO-MS-NH2) membranes was determined from BDS dates, both in dry and hydrated states. For dried samples, the higher values of proton conductivities were: 0.16 mS cm−1 (sPPO, 70 °C) and 0.03 mS cm−1 (sPPO-MS-NH2, 120 °C), and the higher values of proton conductivity increased for the hydrated samples with two orders of magnitude: 36.5 mS cm−1 (sPPO, 40 °C) and 22.4 mS cm−1 (sPPO-MS-NH2, 50 °C). However, the proton conductivity is still dependent on the hydration state, even for the composite membrane. [ABSTRACT FROM AUTHOR]

The polymer composite membranes based on sulfonated poly (ether ether ketone) (SPEEK) and strontium cerate (SrCeO3) were prepared by dispersing SrCeO3 nanoparticles into SPEEK solution with the solvent casting method. The prepared composite membranes are characterized by X-ray diffraction analysis, Fourier infrared spectroscopy, scanning electron microscopy, water uptake, ion exchange capacity, proton conductivity, methanol permeability, thermogravimetric analysis, and oxidative stability. Significant improvement has been attained through the successful combination of the organic and inorganic phases. TGA showed that all the composite membranes exhibited good thermal stability. The maximum proton conductivity of 32.1 mS/cm was achieved at (25 °C) upon incorporating 06 wt.% of the SrCeO3 nanoparticle. The excellent proton conductivity of the membranes can be attributed to the presence of SrCeO3 nanoparticles, which can act as pathways for proton transport. The prepared polymer composite membranes exhibited high selectivity compared with pure SPEEK and Nafion 117. From the observed results, the prepared 94 wt% SPEEK and 06 wt% SrCeO3 composite membranes can be considered opposite polymer electrolyte membranes for the application of direct methanol fuel cell (DMFC) applications. [ABSTRACT FROM AUTHOR]

Dimensional regulation in polyoxometalates is an effective strategy during the design and synthesis of polyoxometalates-based high proton conductors, but it is not available to date. Herein, the precise regulation of dimensionality has been realized in an unprecedented gigantic molybdenum blue wheel family featuring pentagonal {(W)Mo5} motifs through optimizing the molar ratio of Mo/W, including [Gd2Mo124W14O422(H2O)62]38− (0D-{Mo124W14}, 1), [Mo126W14O441(H2O)51]70− (1D-{Mo126W14}n, 2), and [Mo124W14O430(H2O)50]60− (2D-{Mo124W14}n, 3). Such important {(W)Mo5} structural motif brings new reactivity into gigantic Mo blue wheels. There are different numbers and sites of {Mo2} defects in each wheel-shaped monomer in 1–3, which leads to the monomers of 2 and 3 to form 1D and 2D architectures via Mo–O–Mo covalent bonds driven by {Mo2}-mediated H2O ligands substitution process, respectively, thus achieving the controllable dimensional regulation. As expected, the proton conductivity of 3 is 10 times higher than that of 1 and 1.7 times higher than that of 2. The continuous proton hopping sites in 2D network are responsible for the enhanced proton conductivity with lower activation energy. This study highlights that this dimensional regulation approach remains great potential in preparing polyoxometalates-based high proton conductive materials. [ABSTRACT FROM AUTHOR]

An inexpensive membrane with high proton conductivity and high fuel cell performance, which can be an alternative to Nafion for PEMFC (Proton exchange membrane fuel cell), will overcome the obstacle to widespread commercialization of fuel cells due to high cost. For this purpose, SPEEK (sulfonated polyether ether ketone)-PVA (polyvinyl alcohol) blend membranes with colloidal silica additives were synthesized in this study. Ludox AS-40 was used as the colloidal silica source and the blend membrane was prepared by solution casting method. Water uptake capacity, swelling property, size change, dynamic mechanical analysis, ion exchange capacity, AC impedance analysis, hydrolytic and oxidative stability experiments of the synthesized Ludox additives blend membranes for fuel cell application were carried out, and the membranes were also characterized by FTIR (Fourier transform infrared) analysis. While the water uptake capacities of SPEEK/PVA membranes containing 1% Ludox, 5% Ludox, and 10% Ludox at room temperature were found to be 14.08%, 14.84%, and 16.6%, respectively, the water uptake capacities at 80oC increased to 14.73%, 15.17%, and 17.11%. The proton conductivities of 1% Ludox, 5% Ludox and 10% Ludox doped SPEEK/PVA membranes at 80oC were 0.25 S/cm, 0.56 S/cm, and 0.65 S/cm, respectively. Similarly, ion exchange capacities were determined to be 1.41 meq/g, 1.63 meq/g, and 1.71 meq/g, respectively. All Ludox-added membranes exhibited excellent hydrolytic stability, retaining approximately 88% of their mass after 650 h. In addition, in oxidative stability experiments carried out in 4 ppm Fe+ 2 at 80oC, the 10% Ludox-added membrane exhibited the highest weight loss of 88.8% at the end of 24 h, while the 5% Ludox-additive membrane retained 91.6% of its total weight. Considering the proton conductivity and longevity tests of the synthesized membranes, they are thought to be promising structures. [ABSTRACT FROM AUTHOR]

This study explored the catalytic performance of two robust zirconium-based metal–organic frameworks (MOFs), MIP-202(Zr) and UiO-66-(CO2H)2 in the ring-opening of epoxides using alcohols and amines as nucleophilic reagents. The MOFs were characterized by techniques such as FT-IR, PXRD, FE-SEM, and EDX. Through systematic optimization of key parameters (catalyst amount, time, temperature, solvent), MIP-202(Zr) achieved 99% styrene oxide conversion in 25 min with methanol at room temperature using 5 mg catalyst. In contrast, UiO-66-(CO2H)2 required drastically harsher conditions of 120 min, 60 °C, and four times the catalyst loading to reach 98% conversion. A similar trend was observed for ring-opening with aniline –MIP-202(Zr) gave 93% conversion in one hour at room temperature, while UiO-66-(CO2H)2 needed two hours at 60 °C for 95% conversion. The superior performance of MIP-202(Zr) likely stems from cooperative Brønsted/Lewis acid sites and higher proton conductivity enabling more efficient epoxide activation. Remarkably, MIP-202(Zr) maintained consistent activity over five recycles in the ring-opening of styrene oxide by methanol and over three recycles in the ring-opening of styrene oxide by aniline. Testing various epoxide substrates and nucleophiles revealed trends in reactivity governed by electronic and steric effects. The results provide useful insights into tuning Zr-MOF-based catalysts and highlight the promise of the cost-effective and sustainable MIP-202(Zr) for diverse epoxide ring-opening reactions on an industrial scale. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) are compatible with perfluorosulfonic acid (PFSA) polymers due to their rich hydrophilic functional groups and nanoscale particle size, making them suitable as inorganic fillers for proton exchange membranes. In this work, CQDs synthesized by a simple microwave-assisted pyrolysis method were used to improve the performance of PFSA proton exchange membranes. Research indicates that at 80 °C and 100% relative humidity (RH), the proton conductivity of the PFSA membrane increased to 254 mS/cm with the addition of 0.5 wt% CQDs filler, compared to 249 mS/cm for the original PFSA membrane. This enhancement in proton conductivity is likely attributed to the hydrophilic functional groups present on CQDs, such as carboxyl groups (–COOH) and amino groups (–NH2). Furthermore, a notable decrease in hydrogen permeability was observed in the composite membranes due to the incorporation of CQDs. Specifically, the hydrogen permeability of the PFSA/CQDs-2 composite membrane was reduced by approximately 44% compared to the original PFSA membrane. This reduction in hydrogen permeability is likely a result of cross-linking between the sulfonic acid groups in PFSA and the amino groups in CQDs. In conclusion, CQDs contribute to better proton conductivity, lower hydrogen permeability, and enhanced thermal and mechanical stability for PFSA membranes, making them a potential membrane material for high-temperature operation in proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

In this study, polymer-coated anisotropic inorganic nanowires dispersed in PBI matrix were introduced to construct 1D proton conducting channels within PBI. Ionic-liquid and solvothermal methods were used for the synthesis of ZrO2 and W18O49 NWs, which were coated with PVPA and PDDA polymers to increase their proton conductivity. Our results showed that, prepared membranes have amorphous nature due to the dominating presence of PBI. SEM analysis revealed the average thickness of membrane of about 36 µm. TG/DTA analysis detected lower weight loss of W18O49 NWs (total 2.8%) compared to ZrO2 NWs (18%). Proton conductivity analysis showed that, PDDA/W18O49 NWs possess relatively 4 times higher proton conductivity (4 × 10−4 Scm−1) compared to PDDA/ZrO2 NWs (1 × 10−4 Scm−1) at 80 ℃. In addition, PDDA-coated W18O49 NWs dispersed PBI membranes showed the highest fuel cell current density (1.2 A/cm2) and power density (215 mW/cm2) at 150 ℃ after 24 h which is nearly 2.5 times higher than pure PBI membrane. In addition, they exhibited the lowest in-situ proton resistance of about (0.47 Ω) compared with that of pure PBI membrane (0.8 Ω). Our results are introducing new concepts towards the development of thin and efficient polymer electrolyte membranes for PEM fuel cells. [ABSTRACT FROM AUTHOR]

Nafion, a widely utilized commercial membrane in direct methanol fuel cells (DMFC), presents significant limitations due to its cost and susceptibility to high methanol crossover. This study explores alternative membranes, focusing on Sodium Alginate/Poly (Vinyl Alcohol) (SA/PVA) blends with montmorillonite (MMT) modification as an inorganic filler. The MMT content in the SA/PVA membrane was varied from 2 to 20 wt% using the solvent casting method. Optimally, 10 wt% MMT content demonstrated the highest proton conductivity (9.38 mScm−1) and the lowest methanol uptake (89.28%) at ambient temperature. The SA/PVA-MMT membrane exhibited superior thermal stability, optimal water absorption, and reduced methanol uptake, attributed to the electrostatic attraction within the sodium alginate and PVA polymer matrices interacting with H+, H3O+, and –OH ions. The homogeneous dispersion of 10 wt% MMT, along with its hydrophilic properties, facilitated an efficient proton transport channel in SA/PVA-MMT membranes. Increasing MMT content enhanced membrane hydrophilicity, indicating that 10 wt% MMT loading is crucial for adequate water intake to activate proton transfer. This study suggests that the developed membrane holds great potential as a cost-effective alternative with competent performance for future applications. [ABSTRACT FROM AUTHOR]

In bacteria, F-type ATPase (F-ATPase) plays a key role in bioenergetics and couples ATP synthesis/hydrolysis with the transport of ions (H+ or Na+) across the membrane. The ion specificity of the enzyme is determined by the amino acid sequence of subunits c and a. Here, we introduced several mutations (7 in subunit c and 6 in subunit a) into F-ATPase of thermophilic bacterium Bacillus sp. PS3 in order to change the ion specificity of the enzyme from proton to sodium. The mutations did not affect the ATPase activity of the enzyme, but led to loss of proton conductivity and impaired the binding of subunit a to the c-subunit oligomer, rather than changed the ion specificity. [ABSTRACT FROM AUTHOR]

A novel tetraamine, 4,4’-oxy-bis[4-(trifluoromethyl)-1,2-benzendiamine] (7), was synthesized through a seven-step synthetic procedure starting from 1-chloro-4-nitro-2-(trifluoromethyl)benzene (1). Polybenzimidazole CF3-PBI-OO was prepared from 4,4’-oxybis(benzoic acid) (OBA) and tetraamine (7) using Eaton’s reagent as the solvent. To achieve a relatively high molecular weight, the temperature and concentration should be well controlled. CF3-PBI-OO exhibited a high inherent viscosity of 2.1 dL/g, measured in methanesulfonic acid (MSA) with a concentration of 0.2 g/dL at 35 ℃. We provide a relatively fast method to fabricate membranes by dissolving them in MSA. CF3-PBI-OO also required less time (2.7 h) to achieve a saturated PA uptake (271%), when immersed in a 75% phosphoric acid solution at room temperature. CF3-PBI-OO membrane with a PA uptake of 213% demonstrated the optimal combination of properties. The membrane exhibited a high proton conductivity of 115 mS/cm at 160 ℃. The single fuel cell based on CF3-PBI-OO demonstrated a peak power density of 691 mW/cm2 at 160 ℃. It showed superior performance compared to commercially available m-PBI when subjected to the same test conditions. [ABSTRACT FROM AUTHOR]

The focus of the work was on layered perovskite-related materials as potential electrolytic components of devices such as proton-conducting solid oxide fuel cells for clean energy. The possibility of isovalent substitution in the In-sublattice of the two-layer perovskite BaLa2In2O7 has been experimentally investigated. It has been found that the replacement of half the structural positions of In3+ ions by Y3+ ions leads to an increase in oxygen ion conductivity due to an increase in their mobility as a result of an increase in interlayer space. It is shown that the increase in proton conductivity upon doping is due to both an increase in the mobility of the protons and an increase in their concentration. The BaLa2InYO7 exhibits predominantly proton conductivity at temperatures below 500 °C. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded organic frameworks (HOFs) are versatile materials with potential applications in proton conduction. Traditional approaches involve incorporating humidity control to address grain boundary challenges for proton conduction. This study finds vitrification as an alternative strategy to eliminate grain boundary effect in HOFs by rapidly melt quenching the kinetically stable HOF-SXU-8 to glassy state HOF-g. Notably, a remarkable enhancement in proton conductivity without humidity was achieved after vitrification, from 1.31 × 10−7 S cm−1 to 5.62× 10−2 S cm−1 at 100 °C. Long term stability test showed negligible performance degradation, and even at 30 °C, the proton conductivity remained at high level of 1.2 × 10−2 S cm−1. Molecule dynamics (MD) simulations and X-ray total scattering experiments reveal the HOF-g system is consisted of three kinds of clusters, i.e., 1,5-Naphthalenedisulfonic acid (1,5-NSA) anion clusters, N,N-dimethylformamide (DMF) molecule clusters, and H+-H2O clusters. In which, the H+ plays an important role to bridge these clusters and the high conductivity is mainly related to the H+ on H3O+. These findings provide valuable insights for optimizing HOFs, enabling efficient proton conduction, and advancing energy conversion and storage devices. Proton conduction is one of the interesting applications of hydrogen-bonded organic frameworks. Here, the authors report hydrogen-bonded organic framework that can be transformed into glassy state, effectively mitigating grain boundary effects, and significantly enhancing proton conduction performance. [ABSTRACT FROM AUTHOR]

Phosphoric acid doped proton exchange membranes often experience performance degradation above 200 °C due to membrane creeping and phosphoric acid evaporation, migration, dehydration, and condensation. To address these issues, here we present gel-state polybenzimidazole membranes with double cross-linked three-dimensional layered structures via a polyphosphoric acid sol-gel process, enabling stable operation above 200 °C. These membranes, featuring proton-conducting cross-linking phosphate bridges and branched polybenzimidazole networks, effectively anchor and retain phosphoric acid molecules, prevent 96% of its dehydration and condensation, improve creep resistance, and maintain excellent proton conductivity stability. The resulting membrane, with superior through-plane proton conductivity of 0.348 S cm−1, delivers outstanding peak power densities ranging from 1.20–1.48 W cm−2 in fuel cells operated at 200-240 °C and a low voltage decay rate of only 0.27 mV h−1 over a 250-hour period at 220 °C, opening up possibilities for their direct integration with methanol steam reforming systems. Phosphoric acid (PA) doped proton exchange membranes (PEMs) often degrade above 200 °C due to membrane creeping, PA dehydration, and condensation. Here, the authors introduce gel-state polybenzimidazole PEMs with double cross-linked 3D layered structures, enabling efficient and stable fuel cell operation above 200 °C. [ABSTRACT FROM AUTHOR]

The influence of the type of crosslinking agent for poly(vinyl alcohol) (PVA) (glutaraldehyde or epichlorohydrin) on the structure, morphology, thermal stability, and electrochemical properties of composite membranes based on the domestic perfluorinated sulfonic acid copolymer LSC, an analog of Nafion®, has been studied. The introduction of hydrophilic PVA has led to an increase in the moisture content of the membranes, which, taking into account the structural features, affects the proton conductivity. The presence of up to 5 wt % of cross-linked PVA in the composite membrane has not significantly changed the initial structure of LSC. The degree of crystallinity of the composite membranes upon the introduction of PVA has been slightly increased as compared to the original LSC membrane. With an increase in the amount of PVA in the composite, a domain surface morphology has appeared, its roughness being clearly increased. The increase in the PVA content in the LSC-PVA-GA samples has led to a noticeable increase in the temperature of thermal decomposition of sulfonic acid groups, while it has remained almost unchanged for the LSC-PVA-ECH samples. [ABSTRACT FROM AUTHOR]

Low-sulfonation-level polyether sulfone octyl sulfonamide (LSPSO) was blended with a layered double hydroxides (LDHs, Mg2AlCl)/sepiolite nanostructure clay as a filler to create an electrolyte membrane for fuel cell applications. Comprehensive characterization of the composite membranes was conducted, encompassing Fourier-transform infrared spectroscopy, X-ray diffraction, mechanical stability assessment, thermal gravimetric analysis, ion exchange capability, swelling characteristics, water uptake performance, and electrochemical impedance spectroscopy analysis. In comparison to the pristine LSPSO membrane, the presence of LDHs/sepiolite nanoarchitecture material within LSPSO exhibited superior water retention and proton conductivity values, especially at elevated temperatures. The proton conductivity of the composite membranes reached approximately 250 mS/cm, while the unmodified LSPSO membrane only achieved 35 mS/cm at 100 °C. Moreover, LSPSO composite membranes demonstrated enhanced chemical and thermal stability along with higher proton conductivity when compared to pristine LSPSO membranes. These findings highlight the potential of developing tailored LSPSO composite membranes to advance the prospects of commercial applications in proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

An innovative methodology was employed to fabricate ion exchange membranes tailored for fuel cell applications. This approach entailed blending low sulfonated polyether sulfone octyl sulfonamide (LSPSO) with Hectorite (Hect) clay at varying weight percentages (1 wt%, 3 wt%, and 6 wt%). The resultant composite membranes underwent comprehensive characterization via Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis, aiming to assess their surface morphology and thermal resilience. Remarkably, the thermal stability of the composite membrane exhibited a substantial enhancement in comparison to the pristine LSPSO membrane. Moreover, the incorporation of 6 wt% Hectorite into the composite membrane yielded a noteworthy amplification in proton conductivity, achieving a fourfold increase (141.66 mS/cm) as opposed to the LSPSO membrane in isolation (35.04 mS/cm). Consequently, the Hect/LSPSO composite membrane exhibits remarkable potential as an electrolyte membrane for fuel cells operating at temperatures surpassing 100 °C. [ABSTRACT FROM AUTHOR]

Proton transport in nanofluidic channels is not only fundamentally important but also essential for energy applications. Although various strategies have been developed to improve the concentration of active protons in the nanochannels, it remains challenging to achieve a proton conductivity higher than that of Nafion, the benchmark for proton conductors. Here, taking H3Sb3P2O14 and HSbP2O8 as examples, we show that the interactions between protons and the layer frameworks in layered solid acid HnMnZ2O3n+5 are substantially reduced at the monolayer limit, which significantly increases the number of active protons and consequently improves the proton conductivities by ∼8 ‒ 66 times depending on the humidity. The membranes assembled by monolayer H3Sb3P2O14 and HSbP2O8 nanosheets exhibit in-plane proton conductivities of ~ 1.02 and 1.18 S cm−1 at 100% relative humidity and 90 °C, respectively, which are over 5 times higher than the conductivity of Nafion. This work provides a general strategy for facilitating proton transport, which will have broad implications in advancing both nanofluidic research and device applications from energy storage and conversion to neuromorphic computing. High performance proton conductor is highly desired for energy application. Here authors report an increase in the number of active protons in solid acid at the monolayer limit, enabling membranes with proton conductivity 5 times higher than that of Nafion. [ABSTRACT FROM AUTHOR]

A sole inorganic framework-material formulated as [Li(H2O)4][{CuI(H2O)1.5} {CuII(H2O)3}2{WVI12O36(OH)6}]·N2·H2S·3H2O (1), consisting of a hydroxylated polyoxometalate (POM) anion, [{WVI12O36(OH)6}]6− and a mixed-valent Cu(II)- and Cu(I)-aqua cationic complex species, [{CuI(H2O)1.5}{CuII(H2O)3}2]5+, has been utilized to explore its proton conductivity studies. The POM cluster anion is functionalized with six hydroxyl groups, meaning there are six WVI-OH groups per cluster unit. Compound 1, insoluble in water, can be described as an inorganic acid because its water suspension shows an acidic pH. The presence of these six hydroxyl groups per cluster unit having six labile protons has encouraged us to perform proton conductivity studies of this system. The highest proton conductivity of compound 1 is 1.72 ×10−2 S cm−1 at a temperature of 80 °C at 98% relative humidity (RH). Arrhenius plot has been constructed from the temperature-dependent proton conductivity values. The concerned Arrhenius plot has shown good linearity throughout the temperature range of 40 to 80 °C, revealing an activation energy of 0.41 eV. The compound has also shown remarkable stability in the conductivity value for 40 h. The proton conductivity studies of a framework-material [Li(H2O)4][{CuI(H2O)1.5} {CuII(H2O)3}2{WVI12O36(OH)6}]·N2·H2S·3H2O (1) have been performed. Compound 1 exhibits proton conductivity value of 1.72 ×10−2 S cm−1 at a temperature of 80 °C at 98% relative humidity. The concerned Arrhenius plot gives the activation energy value of 0.41 eV. [ABSTRACT FROM AUTHOR]

As the third generation of fuel cells, solid oxide fuel cell (SOFC) provides a clean and low-pollution technology. Electrolyte material, which often plays a vital role in SOFC, has always been the focus and difficulty of research. Y-doped barium cerate-based proton conductor electrolyte, BaCe1–xYxO3–δ (x = 0, 0.05, 0.1, 0.15), were prepared using the nitrate-citrate-glycine combustion method. A series of tests and characterizations were performed to examine the structural, morphological, and electrical properties. X-ray diffraction (XRD) analysis proved that the BCY powders with pure cubic perovskite structure were formed after calcined at 1100 °C. SEM results showed that the BCY ceramics sintered at 1350 °C were dense and well-developed grains. The electrochemical performance of BCY proton conductor electrolyte was determined using the electrochemical impedance spectroscopy in dry air and wet air atmosphere at 400–800 °C. Results showed that Y-doped BaCeO3-based material had superior conductivity in air and the conductivity of proton conductor was significantly improved under wet air environment. Furthermore, the electrical conductivity of BCY samples was related to the amount of Y3+ doping. The conductivity in a water vapor environment achieved a maximal value of 0.039 S cm−1 at 800 °C when x = 0.15. So BaCe1–xYxO3-based materials can be used as a proton conductor electrolyte for SOFC in the medium temperature range. [ABSTRACT FROM AUTHOR]

The perfluorosulfonic acid (PFSA) membrane doped with two-dimensional conductive filler Ti3C2Tx is a fuel cell proton exchange membrane with high application potential. Experimental studies showed that the proton conductivity of Nafion/Ti3C2Tx composite membrane is improved significantly compared with that in pure Nafion. However, the microscopic mechanism of doping on the enhancement of membrane performance is remain unclear now. In this work, molecular dynamics simulation was used to investigate the microscopic morphology and proton transport behaviors of Nafion/Ti3C2Tx composite membrane at the molecular level. The results shown that there were significant differences about the diffusion kinetics of water molecules and hydroxium ions in Nafion/Ti3C2Tx at low and high hydration levels in the nanoscale region. With the increase of water content, Ti3C2Tx in membrane was gradually surrounded by ambient water molecules to form a hydration layer, and forming a relatively continuous proton transport channel between Nafion polymer and Ti3C2Tx monomer. The continuous proton transport channel could increase the number of binding sites of proton and thus achieving high proton conductivity and high mobility of water molecules at higher hydration level. The current work can provide a theoretical guidance for designing new type of Nafion composite membranes. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of polypyrrole coated over sulfonated polyvinyl alcohol and graphene oxide-nanosized ZnO network-based nanocomposite actuators (SPVA/GO/ZnO-Nps/PPy). The solution casting approach was used to create the membrane. HO3SC6H3-1,2-(CO2H)2 was used as a sulfonating agent during the sulfonation process of polyvinyl alcohol. A polypyrrole coating is done on a sulfonated polyvinyl alcohol and graphene oxide-nanosized ZnO network substrate using an aqueous chemico-oxidation polymerization process with in-situ polypyrrole synthesis. The consistent network that can block water loss was also revealed using scanning electron microscopy. An adequate ion-exchange potential of 1.79 meq g−1 was demonstrated by the dry membrane sulfonated polyvinyl alcohol graphene oxide-nanosized ZnO networks with polypyrrole coatings. It was observed that the membrane's absorption capacity at 45 °C was around 80.45% after roughly 24 h of dousing. Excellent proton conductivity of 1.69 × 10−3 Scm−1 was observed by the polypyrrole coating of the nanocomposite membrane. The membrane's capacity to lose water was estimated to be around 37.8% for 10 min, at 6 V. In addition, at 4 V, the electro-mechanical characterization revealed a maximum tip displacement of 15.5 mm. In comparison to earlier published expensive polymer-based membranes, the claimed nanocomposite membrane improved water-absorption, ion-exchange capacity, and ionic-conductivity enhanced the electrical characteristics with good performance of tip deflection. The development of a microgripper based on a polypyrrole coated over sulfonated polyvinyl alcohol and graphene oxide-nanosized ZnO network-based nanocomposites membrane (SPVA/GO/ZnO-Nps/PPy) has a lot of potential for use as soft robotic actuators. [ABSTRACT FROM AUTHOR]

Fuel cells on polybenzimidazole (PBI) membrane belong to high-temperature polymer-electrolyte membrane fuel cells (HT-PEMFC). When a polymer-electrolyte complex of PBI with o-phosphoric acid (PA) is applied as a proton-conducting membrane, the proton conductivity is provided without humidification above 120°C. Hydrogen-air HT-PEMFCs are able of operating effectively at 150–200°C, which allows application of technical hydrogen contaminated with CO as fuel. However, it should be noted that application of conventional "thin-film" Pt/C electrodes based on electrically conductive carbon black with Pt nanoparticles in aggressive PA environment results in electrochemical corrosion of carbon, which leads to the loss of Pt electrocatalyst particles and their aggregation (Ostwald ripening). Evidently, there is a need to replace the carbon black with more stable carbon nanostructured materials. It has been shown that self-supporting mats (essentially "felt") based on carbon nanofibers (CNF) can be used as HT-PEMFC anodes. The CNF mats were obtained in three stages. At the first stage, the nanofiber precursor material was obtained by electrospinning of solution of a copolymer of acrylonitrile with methyl acrylate (with addition of ZrCl4). Then, the mats were stabilized by thermal oxidation (350°C, air). Afterwards, the CNFs were kept in Zn(NO3)2 (porogen) solution and pyrolyzed (1000 C, vacuum). To improve the proton conductivity, N-phosphonoethylated cardo poly(benzimidazole) (PBI-PhT-P) was deposited on the CNF surface which leads to an improvement in the performance characteristics of HT-PEMFC. The obtained materials were examined by electron microscopy. Their specific surface area and specific volume were investigated by the N2 and CO2 adsorption methods (up to 597 m2/g and 0.170 cm3/g). After Pt deposition, the CNFs were successfully tested as anodes (up to 0.4 mA/cm2 at 625 mV) in hydrogen-air HT-PEMFC. [ABSTRACT FROM AUTHOR]

This work presents a method for the synthesis of multifunctional hydrogels based on polymer framework obtained by UV-initiated polymerization of the acrylic monomers (acrylamide, acrylonitrile, and sulfo-group-containing monomer (3-sulfopropyl acrylate potassium salt, 2-acrylamido-2-methylpropane sulfonic acid, and sodium styrene sulfonate)) in the presence of N,N′-methylenebisacrylamide as a cross-linking agent. Composite polymer/silica nanogels have been created in situ using a TEOS-based sol–gel system and the above-mentioned polymeric matrices. The synthesized material characteristics such as composition, morphology, and thermal stability were explored with FTIR, SEM, and DCS. In addition, the effect of temperature, inorganic component content, sulfo-group-containing monomer to proton conductivity and water uptake have been explored. The obtained hydrogels possess proton conductivity up to 19 mSm/cm with potential implying for application in electrochemical devices and superabsorbent material. This method is user-friendly and cost-efficient, and proceeds in an aqueous environment under atmospheric conditions without the use of heavy metal catalysts. [ABSTRACT FROM AUTHOR]

An editorial is presented, discussing the significance of the Nano Research Young Innovators Awards in recognizing the achievements of 33 outstanding researchers under 45 years of age in the field of bio-inspired nanomaterials. It highlights key topics covered by the awardees, including innovative approaches to treat Parkinson's disease, advancements in nanotranslacers, and the development of organic thin-film transistors for disease-related biomarker detection.

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–guest interaction between CB[n] and water molecules offers extra proton-conducting 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. [ABSTRACT FROM AUTHOR]

Perovskite-like materials with mixed ionic and electronic conductivity are considered as promising functional materials for proton-ceramic electrochemical devices. In the present work, a solid-solution series La0.9Sr0.1Sc1–xMnxO3 – δ, where scandium ions in the B-cation position are gradually replaced by manganese ions, was obtained and studied for the first time. The obtained materials were certified by X-ray phase analysis, scanning electron microscopy, and energy-dispersive microanalysis. The dopant influence on the studied materials' sintering ability and morphology is elucidated. The electrical conductivity of the solid solutions as a function of temperature and gas phase humidity was investigated by the dc four-probe method. [ABSTRACT FROM AUTHOR]

Based on the preparation of chloromethylated polysulfone(CMPS), two types of sulfonated polysulfone, naphthalenesulfonic acid type sulfonated polysulfone(PS-NS) and pyrenesulfonic acid type sulfonated polysulfone(PS-TS) were successfully obtained via nucleophilic substitution with 2-naphthol-6,8-disulfonic acid dipotassium(NS) and 8-hydroxy-1,3,6-pyrene trisulfonic acid sodium(TS) as reagents, respectively. The PS-NS and PS-TS Proton exchange membranes (PEMs) were obtained by solution casting method after characterizing their structure by FT-IR and 1H-NMR. The impact of phenyl side chain on performance including water uptake(WU), swelling ratio(SR) and proton conductivity(PC) of PEMs were explored. Atomic force microscopy(AFM) shows that the phase separation structures of PS-NS and PS-TS PEMs are distinct due to the positioning of the hydrophilic sulfonic acid groups far away from the hydrophobic main chain. So the PS-NS and PS-TS PEMs keep excellent size stability, oxidative stability and methanol permeability at high WU. At the same bonding amount(BA) of sulfonic acid, due to less hydrophilic chain segment and a larger number of sulfonic acid groups in the hydrophilic chain segment, which is conducive to the aggregation of ion cluster. The PS-TS present better size stability and anti-oxidative at high WU. The SR of PS-TS-3 PEM was only 20.3 and 48.1%. Meanwhile, the methanol permeability was only 7.54 × 10−7cm2·s−1 at room temperature, much lower than commercialization Nafion115 PEM (16.8 × 10−7cm2/s at room temperature). The research results are of great significance for the design and preparation of high-performance membrane materials. [ABSTRACT FROM AUTHOR]

The present study selected 5, 5′-((6-(ethylamino)-1, 3, 5-triazine-2, 4-diyl) bis(azanediyl))diisophthalic acid (H4EATDIA) as ligand and an amino-functionalized cuprum-based MOF (EA-JUC-1000), successfully synthesized by microwave-assisted method, for proton conduction and dopamine sensing applications. In order to enhance the proton-conducting potential of EA-JUC-1000, the Brönsted acid (BA) encapsulated composites (BA@EA-JUC-1000) are dopped into chitosan (CS) to form a series of hybrid membranes (BA@EA-JUC-1000/CS). The impedance results display that the best proton conductivity of CF3SO3H@EA-JUC-1000/CS-8% reaches up to 1.23 × 10–3 S∙cm−1 at 338 K and ~ 98% RH, 2.6-fold than that of CS. Moreover, the EA-JUC-1000 is in-situ combined with reduced graphene oxide (rGO) (rGO/EA-JUC-1000), which makes EA-JUC-1000 have a wide detection range (0.1 ~ 500 μM) and a low limit of detection (50 nM), together with good anti-interference performance, reproducibility and repeatability. In addition, the electrochemical sensing method has been successfully applied to detect DA in bovine serum samples. The dual-functional MOF-based hybrid membrane and composites including proton conduction and DA sensing would provide an example of practical application for MOFs. [ABSTRACT FROM AUTHOR]

Single crystals of nitrate phosphate Pb2[PO4](NO3)⋅H2O (LNP), which have electrical conductivity and magnetic properties, were prepared by mild hydrothermal synthesis; sp. gr. P21/c, a = 9.5709(4) Å, b = 7.3061(3) Å, c = 10.5644(5) Å, β = 106.37(1)°, Rhkl = 0.0548. This approach simplifies the preparation of the crystals compared to their synthesis from gels used previously. The new compound is the second representative of this class containing a mixed anionic radical. The structure determination, which revealed the layered nature and allowed the positioning of a part of hydrogen atoms of water molecules, provides an explanation for the proton conductivity of the crystals found previously. [ABSTRACT FROM AUTHOR]

Ionic and electronic transport in electrodes is crucial for electrochemical energy storage technology. To optimize the transport pathway of ions and electrons, electrode materials are minimized to nanometer-sized dimensions, leading to problems of volumetric performance, stability, cost, and pollution. Here we find that a bulk hexagonal molybdenum oxide with unconventional ion channels can store large amounts of protons at a high rate even if its particle size is tens of micrometers. The diffusion-free proton transport kinetics based on hydrogen bonding topochemistry is demonstrated in hexagonal molybdenum oxide whose proton conductivity is several orders of magnitude higher than traditional orthorhombic molybdenum oxide. In situ X-ray diffraction and theoretical calculation reveal that the structural self-optimization in the first discharge effectively promotes the reversible intercalation/de-intercalation of subsequent protons. The open crystal structure, suitable proton channels, and negligible volume strain enable rapid and stable proton transport and storage, resulting in extremely high volumetric capacitance (~1750 F cm–3), excellent rate performance, and ultralong cycle life (>10,000 cycles). The discovery of unconventional materials and mechanisms that enable proton storage of micrometer-sized particles in seconds boosts the development of fast-charging energy storage systems and high-power practical applications. Nanostructured electrode materials pose several challenges, including poor volumetric performance, severe side reactions, high costs, and complexity. Here, the authors develop a micrometer-sized bulk hexagonal molybdenum oxide with unconventional charge storage mechanism for fast and stable proton storage. [ABSTRACT FROM AUTHOR]

Nanocomposite membranes of average thickness 100 µm were successfully fabricated using a phase inversion method which involved use of sulfonated polyether ether ketone (SPEEK) incorporated with nanoclays of cloisite 30B and bentonite. The membranes were characterized for their organic functional groups, morphological structure, thermal and physical properties under the influences of cloisite 30B and bentonite addition in SPEEK matrix. The presence of nanoclays was confirmed by the changes observed in the membrane morphology and improved glass transition temperature in pristine SPEEK membrane. The fuel cell performance of the membranes was determined by their water uptake capacity, methanol permeability and proton conductivity. The 0.5 wt% addition of cloisite and bentonite in SPEEK showed 2.1% reduction of water uptake as compared to the pristine SPEEK membrane. The cloisite-added SPEEK membrane showed the average proton conductivity of 3.05 × 10–5 S cm−1 at 80 °C. Nevertheless, cloisite- and bentonite-incorporated SPEEK nanocomposite membranes demonstrated the reduced proton conductivity of 6.14% in the methanol permeability as compared to the pristine SPEEK membrane. Hence, the modified SPEEK nanocomposite membranes with cloisite and bentonite are being suggested to be a promising proton exchange membrane for direct methanol fuel cell. [ABSTRACT FROM AUTHOR]

Present work demonstrates development and characterization of Nexar-based nanocomposite membranes to evaluate their potential as an alternative to Nafion. Nanocomposite membranes are characterized through XRD, FTIR, SEM, and TGA for crystallinity, surface morphology, functionalities, and thermal stability. Membrane thickness, and protonic resistivity are determined. Modification of Nexar with doped silica and sulfonated silica nanoparticles is checked for water uptake (UR), swelling ratio (SR), ion exchange capacity, proton conductivity at different temperatures, humidity, and activation energies. Incorporating silica and functionalized silica into Nexar drastically changed WU and SR. Proton conductivity improved by 58.8% for sulfonated silica membrane, comparing pristine Nexar. At low humidity, composite membranes showed better proton conductivity than pristine Nexar. Low activation energies supported mainly Grotthus mechanism for proton transport. Thus, present work suggests Nexar-based functionalized nanocomposite membranes owing to higher IEC and less swelling ratio may help higher proton conductivity necessary for PEM fuel cell operation. [ABSTRACT FROM AUTHOR]

Composite membranes comprising sulfonated poly (ether ether ketone) (SPEEK) blended with varying proportions of sulfo ethyl cellulose (SEC) at 5 wt% and 10 wt% were fabricated for fuel cell application. The structural, morphological, and thermal properties of these membranes were investigated using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The composite membranes exhibited enhanced thermal stability and increased water absorption compared to the pristine SPEEK. Moreover, the proton conductivity of the composite membranes surpassed that of pure SPEEK, reaching up to 110 mS/cm at temperatures exceeding 100 °C. [ABSTRACT FROM AUTHOR]

The surface morphology, structural organization, and transport properties of composite membranes based on Russian Nafion-type perfluorinated copolymers filled with zirconium dioxide nanoparticles are studied using atomic force and scanning electron microscopy, X-ray structural analysis, and thermal analysis. A relationship between the morphology of the free surface and the "substrate" surface of Nafion-LSC-1 proton-conductive film membranes and the concentration of zirconium-dioxide nanoparticles (ZrO2) is found. Atomic force and scanning electron microscopy reveals a gradient in the concentration of zirconium-dioxide nanoparticles, with the highest concentration on the substrate side of the membrane. The free surface is characterized by the presence of two phases alternating over the surface area of the membrane, which may be due to the presence of hydrophilic and hydrophobic regions. Zirconium nanoparticles form associates with sizes up to 300 nm. Wide-angle X-ray diffraction data suggest that Nafion-LSC-1 composite membranes have a mesomorphic structure when the concentration of zirconium-dioxide nanoparticles is 1.6 wt %, while the precursors of these membranes are characterized by a crystalline structure. The samples of Nafion-LSC-1 and composite membranes filled with 0.53, 1.12, and 1.61 wt % of nanoparticles are characterized by moisture content, proton conductivity, and heat resistance. [ABSTRACT FROM AUTHOR]

Designing and synthesis of cost-effective and improved methanol permeable and proton conductive membranes are the main challenges for preparation of polymeric electrolyte membrane (PEM). Herein, a cost-effective PEM membrane based on phosphorylated polyvinyl alcohol (PVA)-grafted-cellulose acetate (CA) was prepared by a solution-casting technique. Water and methanol uptakes of phosphorylated PVA/CA membranes were characterized as function with the molar ratio of CA. Additionally, structure and morphology of phosphorylated PVA/CA (Ph-PVA/CA) membranes were verified by FT-IR analysis, SEM investigation. Furthermore, ion exchange capacity (IEC), proton conductivity and methanol permeation of Ph-PVA/CA membranes were examined based on the concentration of OPA basically. The results manifested a perceptible improvement in proton conductivity from 0.035 to 0.05 S/cm at 25 and 70 °C, respectively using 600 μL of OPA, and IEC of 2.1 meq/g using 400 μL of OPA at ambient temperature. On the other hand, methanol permeability (P = 1.08 × 10–10 cm2/s) was lower than Nafion 117 admirably. The optimum OPA concentration was 200 μL according to conductivity measurements (at 10% PVA, 150 μL GA, and CA 7%). Finally, prepared Ph-PVA/CA membranes exhibited enhancement in critical natures such as proton conductivity and IEC combined with its low-cost materials, which make them excellent candidate as PEM for DMFCs application. [ABSTRACT FROM AUTHOR]

Efforts in design and optimization of catalyst layers for polymer electrolyte fuel cells hinge on mathematical models that link electrode composition and microstructure with effective physico-chemical properties. A pivotal property of these layers and the focus of this work is the proton conductivity, which is largely determined by the morphology of the ionomer. However, available relations between catalyst layer composition and proton conductivity are often adopted from general theories for random heterogeneous media and ignore specific features of the microstructure, e.g., agglomerates, film-like structures, or the hierarchical porous network. To establish a comprehensive understanding of the peculiar structure-property relations, we generated synthetic volumetric images of the catalyst layer microstructure. In a mesoscopic volume element, we modeled the electrolyte phase and calculated the proton conductivity using numerical tools. Varying the ionomer morphology in terms of ionomer film coverage and thickness revealed two limiting cases: the ionomer can either form a thin film with high coverage on the catalyst agglomerates; or the ionomer exists as voluminous chunks that connect across the inter-agglomerate space. Both cases were modeled analytically, adapting relations from percolation theory. Based on the simulated data, a novel relation is proposed, which links the catalyst layer microstructure to the proton conductivity over a wide range of morphologies. The presented analytical approach is a versatile tool for the interpretation of experimental trends and it provides valuable guidance for catalyst layer design. The proposed model was used to analyze the formation of the catalyst layer microstructure during the ink stage. A parameter study of the initial ionomer film thickness and the ionomer dispersion parameter revealed that the ionomer morphology should be tweaked towards well-defined films with high coverage of catalyst agglomerates. These implications match current efforts in the experimental literature and they may thus provide direction in electrode materials research for polymer electrolyte fuel cells. [ABSTRACT FROM AUTHOR]

In this research, halloysite nanotubes (HNTs) modified with polydopamine and phosphotungstic acid (PWA) were used to enhance the performance of the SPEEK-based proton exchange membrane (PEM). The PEEK sulfonation process was carried out through an advanced method to obtain a higher degree of sulfonation. To provide more proton-transferring pathways in the structure of the membrane, polydopamine and PWA were coated on the outer and inner/outer surfaces of HNTs (named as DHNT and PHNT), respectively. Coating PWA on the inner surface of HNTs through the application of vacuum was a novel approach in this study that was validated by Fourier transform infrared spectroscopy (FTIR) analysis. The high acidity of PWA, the presence of hydrophilic groups in the structure of polydopamine, and the tubular structure of HNTs improved the water uptake and proton conductivity of the modified PEMs. Accordingly, the DHNT- and PHNT-modified PEMs exhibited 33% and 83% higher water uptake compared to the neat SPEEK membrane. Proton conductivities of the membranes modified with DHNT and PHNT at 60 °C and 100% relative humidity were 63% and 86% higher than that of the neat SPEEK membrane, respectively. In addition, the membrane performance in MFC showed that the cell equipped with the PHNT-modified membrane achieved 7.6% greater maximum power than the commercial Nafion117 membrane. [ABSTRACT FROM AUTHOR]

The zirconium ethylenediamine tetramethylene phosphonate (ZrEDTMPS) proton conductor with –PO3H2 groups which can easily form hydrogen bonds and encourage proton transfer in low RH is synthesized and doped into the PBI-based membranes. The epoxy groups of tetrafunctional N, N, N', N'-tetraglycidy-4,4'-diaminodiphenylmethane (TGDDM) react with the NH groups in polybenzimidazole (PBI) and form a cross-linking network structure to improve the mechanical properties, oxidative stability and dimensional stability of the composite membranes. At 180 °C, the proton conductivity of the mPBI-TGDDM (10%)/ZrEDTMPS (30%) is 0.122, 0.050, and 0.029 S cm−1 at 100%, 50%, and 0 RH, respectively. Meanwhile, the mPBI-TGDDM/ZrEDTMPS membranes exhibit high oxidative stability (the mass loss of membranes is 2.1%). Compared with Nafion 117 (5.5 × 10−7 cm2 s−1), the methanol permeability of mPBI- TGDDM/ZrEDTMPS membrane at 70 °C (6.38 × 10–8 cm2 s−1) is one order of magnitude lower. The mPBI-TGDDM/ZrEDTMPS membranes have good comprehensive performance and can be used in proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

The present work deals with the fabrication of cost-efficient nanocomposite proton exchange membrane (PEM), prepared by incorporation of nanoparticles of Fly Ash (FA) collected from M/s Bina thermal power plant Madhya Pradesh India; within the host PVDF [poly(vinylidene fluoride)] polymer matrix. Subsequently, the nanocomposite membranes are treated with the well-known sulfonating agent chlorosulfonic acid at 60˚C for 1.5 h. The successful incorporation of FA nanoparticles within the host polymer structure along with the sulfonation of the nanocomposite membranes was confirmed by using FTIR, XRD, FESEM-EDX, and AFM studies. The ion exchange capacity (IEC) and proton conductivity (PC) of nanocomposite membranes are observed to be 0.58 meq g−1 and 3.30 × 10−2 S cm−1 respectively. Further, it was interesting to note that the fabricated membranes exhibited enhanced water uptake capacity up to 19.6% with supressed methanol crossover (1.7 × 10−7cm2/s). Among all the fabricated membranes, the membrane SPF-5 (containing 5% w/w FA), exhibited significantly high membrane selectivity 1.94 × 105 Scm−3 s over corresponding Nafion-117 (2.47 × 104 Scm−3 s), which clearly indicates its potency towards an alternative to costly Nafion-117 for DMFCs (direct methanol fuel cells) application. [ABSTRACT FROM AUTHOR]