Proton Diffusion Research Articles

Discrimination of Brain Abscess and Necrotic Brain Tumor with Proton MR Spectroscopy and Diffusion-Weighted Imaging

Objective: To compare the efficacy of MR spectroscopy and diffusion-weighted imaging in discriminating between cystic or necrotic tumors and pyogenic brain abscesses.Study Design: A retrospective study design.Place and Duration of Study: The Study was conducted at the Radiology Department of Nishtar Hospital Multan and General Hospital Lahore, Pakistan, from January 2022 to January 2023. Methods: A total ten patients were included in the study. Of 10 patients, 5 had pyogenic abscesses, and 5 had tumors. Tumors were metastases (2 patients), glioblastomas (2 patients), and anaplastic astrocytoma (1 patient). Proton MR spectroscopy and diffusion-weighted imaging were performed in all patients. Results: Results showed that significant resonance lines (creatine/phosphocreatine, N-acetyl aspartate, and choline) observed in normal brain parenchyma were missing in abscesses or necrosis. MR spectroscopy of abscess showed multiple resonance peaks. Diffusion-weighted images showed that all pyogenic abscesses had lower ADC values and were hyperintense compared to normal brains. Conclusion: Diffusion-weighted imaging is more accurate and less time consuming method for discrimination of brain lesions compared to MR spectroscopy.
 How to cite this: Saqib HA, Asghar A, Firdous A, Zahra M, Islam Z, Mushtaq S. Discrimination of Brain Abscess and Necrotic Brain Tumor with Proton MR Spectroscopy and Diffusion Weighted Imaging. Life and Science. 2023; 4(4): 432-437. doi: http://doi.org/10.37185/LnS.1.1.431

Confinement and interface engineering of CuSiO3 nanotubes for enhancing CO2 electroreduction to C2+ products

Electrochemical CO2 reduction (ECR) to C2+ products is an efficient method to accomplish intermittent energy storage and CO2 utilization. Developing high-selectivity electrocatalysts for C2+ products, especially C2+ alcohols, have attracted more attention but still remains a major challenge. Here, three kinds of short nanotube (<100 nm), long nanotube (>100 nm), and long nanotube-assembled hollow sphere CuSiO3 catalysts with different confined space are fabricated for boosting the ECR to produce C2+ products selectivity. Long CuSiO3 nanotubes exhibit a higher yield of C2+ alcohols (26.8 %) and more satisfactory Faraday efficiency (FE) of 69.5 % for C2+ products than short nanotubes and nanotube-assembled hollow spheres. The confinement effect of long CuSiO3 nanotubes is conducive to promoting the dimerization of the key reaction intermediate (*CO), inhibiting the diffusion of protons and the side-reaction hydrogen evolution reaction (HER). The formed Cu0/Cu+ interfaces in CuSiO3 nanotubes promote the dimerization reactions of adsorbed *CO. The synergistic effect of nanotubes confinement and Cu0/Cu+ interfaces facilitate the CC coupling reaction to C2+ products via ECR.

Lithium-induced subacute diencephalic angio endotheliopathy.

A 65-years-old woman with bipolar affective disorder presented to our ED with a severe lithium intoxication and the recent onset of confusion, clumsiness, and tremors. Symptoms worsened to stupor and anarthria immediately after hospital admission. Gadolinium-enhanced brain Magnetic Resonance Imaging (MRI) showed signal hyperintensity involving both thalami in T2weighted (T2w)/Fluid Attenuated Inversion Recovery sequences (right > left), restricted areas of proton diffusivity at the level of both occipital lobes and a sharp contrast enhancement of thalami, rhombencephalon, and of leptomeninges from either the temporal, parietal, occipital lobes as well as from the cerebellar folia (right > left). These findings were consistent with a severe form of Posterior Encephalopathy known as Subacute Diencephalic Angio Endotheliopahty (SDAE). In addition, Magnetic Resonance Angiography revealed thrombosis of the right transverse and sigmoidal sinuses up to confluence with the jugular vein. The MRI picture resolved one month later after a course of high dosage dexamethasone. The patient deceased one month after discharge, mainly due to Diabetes Insipidusassociated hypernatremia. Dissecting the "Pandora's box" represented by complex MRI findings (SDAE and sinus thrombosis) in lithium-induced neurotoxicity is fundamental in timely recognizing this threating but potentially reversible clinical picture.

Molecular analysis of hydrogen-bond structures in polymer electrolyte membrane in polymer electrolyte fuel cells below freezing temperatures

The PEFC has been attracted to achieve carbon neutralization with using of cars and so on. Unclearness of the internal state of the polymer electrolyte membrane (PEM) below freezing temperature is one of the biggest problems toward expansion of operating temperature. Our final objective is to reveal the internal state of PEM and transport mechanism in such environment. We performed the reactive force field molecular dynamics to analyze the internal structure of PEM because under such environment chemical reaction is the key transport mechanisms. A radial distribution function (RDF) was performed to analyze the structure in PEM. Our RDF was in good agreement with other simulation results. We found the increase of water molecules in the overlapped solvation area with the decrease in temperature. The water molecules hardly move in the overlapped area, indicating that proton diffusivity decreases.

Proton diffusion in PAM hydrogels

AbstractHydrogels are widely used in the field of biomedicine because of their excellent biocompatibility. In most cases, the pH range applicable to drugs is limited, so it is meaningful to study the diffusion of protons in hydrogels. In this work, the diffusion rate of protons in hydrogels was monitored by a self‐made device, and the factors affecting the diffusion rate of protons were studied. The self‐made device consists of a supply chamber and a receiving chamber with a piece of hydrogel sandwiching between them. It was found that the thickness of hydrogel had a great influence on proton diffusion. The thicker the hydrogel is, the slower the proton diffusion rate is. At the same time, the diffusion coefficient of protons in PAM hydrogel was calculated to be 1.28 ± 0.09 × 10−5 cm2/s (HCl, 25°C). The diffusion coefficient is a function of temperature, and its value increases with the increase in temperature. The effect of the solid content of hydrogel on proton diffusion was also considered, but in the range of solid content 1.81%–10.07%, the proton diffusion rate was almost unaffected. Moreover, anions also have a decisive effect on proton diffusion, with smaller anions leading to faster proton diffusion in the hydrogel.

Aqueous Organic Batteries Using Proton as Charge Carrier.

Benefiting from the merits of low cost, non-flammability and high operational safety, aqueous rechargeable batteries have emerged as promising candidates for large-scale energy storage applications. Among various metal-ion/non-metallic charge carriers, proton (H+ ) as a charge carrier possesses numerous unique properties such as a fast proton diffusion dynamics, a low molar mass and a small hydrated ion radius, which endow aqueous proton batteries (APBs) with a salient rate capability, a long-term life span and an excellent low-temperature electrochemical performance. In addition, redox-active organic molecules, with the advantages of structural diversity, rich proton-storage sites and abundant resources, are considered as attractive electrode materials for APBs. However, as far as application is concerned, the charge storage and transport mechanisms of organic electrodes in APBs is still in infancy. Therefore, finding suitable electrode materials and uncovering the H+ storage mechanisms are significant for the applications of organic materials in APBs. Herein, the latest research progresses on organic materials such as small molecules and polymers for APBs are reviewed. Furthermore, a comprehensive summary and evaluation of APBs employing organic electrodes as anode and/or cathode is provided, especially on their low-temperature and high-power performances, along with systematic discussions for guiding the rational design and the construction of APBs based on organic electrodes. This article is protected by copyright. All rights reserved.

(Invited) First-Principles Molecular Dynamics Investigations of Proton and Hydroxide Transport in Model Anion-Exchange- and Proton-Exchange Membranes in Nanoconfined, Low-Hydration Environments

Fuel cell-based anion-exchange membranes (AEMs) and proton exchange membranes (PEMs) have considerable potential as cost-effective, clean energy conversion devices. However, a fundamental atomistic understanding of the hydroxide and hydronium diffusion mechanisms in AEM and PEM environments is an ongoing challenge. In recent years, nano-confined structures have been exploited in the study of cost-effective and reliable polymer architectures for electrochemical devices. In this study, first-principles molecular dynamics simulations are employed to investigate the influence of the water distribution, temperature, internal geometry, cation chemistry, and presence of carbon dioxide on the diffusion rate of protons and hydroxide ions in nanoconfined geometries that serve as mimics of PEM and AEM environments and to reveal key design principles1-8. The simulations indicate that the water distribution is a determinative factor in the diffusion process, which is also arrested when carbon dioxide is present. Moreover, it is found that hydroxide diffusion in AEMs is largely vehicular or a combination of vehicular and structural while proton diffusion in PEMs is largely structural. Pairs of cations in AEMs create bottlenecks for hydroxide diffusion while the anion groups in PEMs become active participants in proton diffusion. It is found that the temperature dependence of hydroxide diffusion in AEMs is non-monotonic, exhibiting a “kink” over a particular temperature range at which dD OH ─/dT < 0, a finding that is confirmed experimentally. The presence of carbon dioxide is found to suppress hydroxide diffusion, also in agreement with experiment. Looking forward, we investigate the influence of the solvent chemistry on proton transport and propose new nanoconfined environments with the potential to enhance proton transport rates considerably using these liquids.

A Negative-Based TiO2 Electrode for Aqueous Proton Batteries

Complementary solutions to Li-ion batteries must be studied for the growing need for energy demand. Accordingly, we have been interested in developing negative electrode materials of TiO2 capable of reversibly intercalating proton ions for aqueous batteries. One of these batteries’ main challenges comes from the low potential window available. Aqueous batteries cannot provide sufficient energy density with a thermodynamic working potential of only 1.23V. To do so, we have optimized the intrinsic transport properties of proton-ions can lead to the reduction of side reactions such as Hydrogen Evolution Reaction (HER).Solvothermal route synthesis made at different temperatures (from 90°C to 150°C) gives access to different TiO2 structures. At 90°C, a lamellar type lepidocrocite is obtained, including sheets of “TiO2” and water in the inter-lamellar spaces. This inter-lamellar space allows proton conduction by the Grotthus mechanism [1]. But, lepidocrocite type TiO2has been shown to be a non-conductive ionic conductor. To make it conductive, different cations can be inserted into the inter-lamellar space during the solvothermal synthesis, thus allowing the reorganization of water molecules, then facilitating the intercalation, conduction, and diffusion of protons [2]. Several levels of Zn2+ were tested: from 10 to 50 mol% relative to Ti4 +. At 150°C, we have been able to stabilize a complete condensed anatase (one polymorph of TiO2) phase while a defect anatase phase has been synthesized at a temperature between 90°C and 150°C. Interestingly, the quantity of defect can be tuned by the temperature and the hydrolysis ratio, h=nH2O/nTi=3.33 [3]. These defects are mainly cationic vacancies, thanks to X-Ray Pair Distribution Function (PDF) analysis.The electrochemical properties of these materials (shaped with carbon black as conductive support and Nafion as a binder) were studied in half-cell aqueous electrolyte buffered at pH 5 (CH3COOH/CH3COOK, pKa = 4.76, (1M)). Experimental capacities of more than 100 mAh/g, 80% of coulombic efficiency over 100 cycles have been obtained and potentials down to -1.4V (V vs Ag/AgCl, KCl saturated) have been achieved.For defective anatase (synthesized at 110°C), the CV curves exhibit two distinct peaks that can be linked to the co-existence of two sites for proton intercalation. The proton can be intercalated either inside a vacancy or within the lattice. This behavior allows a promising working potential of -1.6V with a gravimetric capacity of 250 mAh.g-1 with a 90% of efficiency over 50 cycles. Finally, the relationship between structure and electrochemical properties will be discussed in this presentation with the objective of designing an efficient MnO2/TiO2 aqueous battery.REFERENCE:[1] Wu, X.; Hong, J. J.; Shin, W.; Ma, L.; Liu, T.; Bi, X.; Yuan, Y.; Qi, Y.; Surta, T. W.; Huang, W.; Neuefeind, J.; Wu, T.; Greaney, P. A.; Lu, J.; Ji, X. Nat. Energy 2019, 4 (2), 123–130 [2] Chimie, E. D.; Analytique, C.; Centre, D. P.; Kang, P. S. Sorbonne Université Design de Matériaux Lamellaires Par Chimie Douce Pour Batteries à Proton et Ion Multivalent. 2020.[3] Kang, S; Singh. A; Badot, J-c; Reeves, K; Durand-Vidal, Serge, Legein, C; Body, Monique, Dubrunfaut, O; Borkiewez, O; Tremblay, B; Laberty-Robert, C; Dambournet, D Chemistry of Materials 2020 32 (21), 9458-9469 Figure 1

Promoting Hydrogen Evolution and Oxidation by Reconstructing Hydrogen-Bonding Network of Interfacial Water

The hydrogen evolution and oxidation reactions (HER/HOR) at the electrode-water control the performance of water electrolyzers and hydrogen fuel cells, two important devices for deep decarbonization of our economy (1). Platinum (Pt) catalyzes the HER/HOR with exceptional activity and stability across a wide pH range. However, its activity progressively decreases by about two orders of magnitude as the pH increases from 0 to 13 (2, 3). The lack of understanding of this pH dependence reflects our fundamental knowledge gaps in electrochemistry and has hindered the advancement of alkaline electrolyzers and fuel cells.Herein, we promoted the HER/HOR of Pt in base by introducing N-methylimidazoles in the Pt-water interface. In situ spectroscopic characterization of the interface together with computations showed that the N-methylimidazoles form strong hydrogen-bonding with neighboring water molecules thereby reconstructing the H-bond network of interfacial water. We accordingly established a unified mechanism by which the HER/HOR in acid and base proceeds via diffusion of protons and hydroxides, respectively through the H-bond network of interfacial water by the Grotthuss mechanism. This mechanism accounts for the pH-dependent HER/HOR kinetics of platinum, a long-standing puzzle. Utilization of N-methylimidazoles as the HER/HOR probes and promoters not only leads to the elucidation of the HER/HOR mechanism but also holds great promise for applications. We have demonstrated 40% performance improvement of an anion exchange membrane water electrolyzer by adding 10-5 M 1,2-dimethylimidazole into the 0.1 M potassium hydroxide solution fed into its Pt cathode. Acknowledgements This work was supported by the Office of Naval Research (ONR) grant N000141712608 (Q.J.)This research used beamline 7-BM (QAS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory Contract DE-SC0012704. Beamline operations were supported in part by the Synchrotron Catalysis Consortium Grant DE-SC0012335. V. R. Stamenkovic, D. Strmcnik, P. P. Lopes and N. M. Markovic, Nat. Mater., 16, 57 (2017). J. Durst, A. Siebel, C. Simon, F. Hasché, J. Herranz and H. A. Gasteiger, Energy Environ. Sci., 7, 2255 (2014). W. Sheng, Z. Zhuang, M. Gao, J. Zheng, J. G. Chen and Y. Yan, Nat. Commun., 6 (2015). Figure 1

Modification of Misfit-Layered Cathode Materials for Improving Electrocatalyic Activity in Reversible Protonic Ceramic Cells

The demand for sustainable regeneration energies such as solar and wind has been continuously increasing by the rise of environmental issues. However, several major technical issues such as intermittent electricity production and high system construction cost are major obstacles to large-scale commercialization for regeneration energies [1]. Reversible protonic ceramic cells (RPCCs) can be an alternative choice because of their high efficiency, long-term durability at intermediate temperatures, and bifunctionality for producing both hydrogen and electricity in an electrochemical device [2]. Until now, perovskite-structured cathode (air/steam electrode) materials have been in spotlight due to their fast oxygen reaction kinetics in RPCCs [3]. However, in spite of their high electrocatalytic activity for oxygen electrode reactions (oxygen evolution and reduction), low phase stability in humid atmospheres, thermal expansion mismatch to common proton electrolytes, and relatively low proton conductivity of RPCCs are still major obstacles to enter the era of hydrogen economy [4, 5]. Hence, we demonstrate novel misfit-layered structure Ca3Co4O9+δ (CCO)-based materials to overcome these technical issues with superior catalytic activity for high performance RPCCs. The thermal expansion coefficient value of CCO is 10-12×10−6 K−1, which is relatively similar to that of the BaCeO3-based proton electrolytes, implying that the CCO-based materials are thermo-mechanically stable during cell operations [6]. In addition, the needle-like morphology of the CCO-based materials is quite valuable in the supply of steam (or air) to the catalytic active sites and elimination the water produced by the electrochemical reaction. Furthermore, with the doping of alkali metal ion (Li, Na, and K) into Ca-site, CCO generates extra charge carrier species with the modified Co oxidation state. This triggers the proton uptake and diffusion properties of CCO-based materials with the improved electrical conductivity. As a result, 5 mol% Na-doped CCO-cell shows exceptionally high performance in both protonic ceramic fuel cell and electrolysis cell modes for RPCCs.

Recycling of PFSA-Based Membranes and Their Re-Application in PEM Fuel Cells

The commercialization of PEM fuel cells offers a promising opportunity to overcome our dependence on fossil fuels and provides an attractive alternative for automotive and stationary power applications.[1] However, PEMFCs are still costly in production, with the main cost factor due to the fabrication of the perfluorosulfonic acid (PFSA)-based proton exchange membrane and the noble metal catalysts.[2,3] Recycling of these components could increase the economic attractiveness of PEMFCs. However, while the high resistance of the ionomer membrane to thermal and chemical degradation is favorable for their use in fuel cells, it also makes membrane recycling a major challenge.Here, we present a newly developed recycling strategy to recover PFSA-based membranes after operation by a hydrothermal treatment. Both short side chain (SSC) and long side chain (LSC) ionomers with EWs of 800 and 1000 were investigated. In contrast to previously published methods, we were able to recover the PFSA ionomer by using water instead of high-boiling organic solvents, such as DMF or DMSO.[4,5] The recycled membranes were obtained from the recycled PFSA ionomer solution by doctor-blading. They were investigated by in-situ Raman techniques for studying the water uptake and analyzed by IR and small-angle X-ray scattering (SAXS) techniques to get a more detailed insight into their morphology. In single cell tests at standard (80 °C) and enhanced (up to 130 °C) PEMFC operating temperatures, the recycled membranes showed an increased cell performance as compared to the pristine 3M-800EW membrane. Solid-state NMR measurements confirmed that no chemical changes in the membrane occurred due to the heat-treatment process.We assume that the observed performance boost can be attributed to an increased water uptake and retention. Furthermore, a change in the polymer matrix formation may be responsible for the observed behavior, which led to an expanded water filled channel structure, where water can accumulate to facilitate proton diffusion as H3O+ through the channels. To confirm this assumption, the morphology of the recycled membranes will be investigated by in situ SAXS measurements at different temperatures and degrees of hydration.[1] I. Staffell, D. Scamman, A. Velazquez Abad, P. Balcombe, P. E. Dodds, P. Ekins, N. Shah, K. R. Ward, Energy Environ. Sci. 2019, 12, 463–491.[2] J. Fan, M. Chen, Z. Zhao, Z. Zhang, S. Ye, S. Xu, H. Wang, H. Li, Nat. Energy 2021, 6, 475–486.[3] D. Papageorgopoulos, Fuel Cell R&D Overview. 2019 Annual Merit Review and Peer Evaluation Meeting, 2019.[4] Q. Xu, X. Chen, S. Wang, C. Guo, Y. Niu, R. Zuo, Z. Yang, Y. Zhou, C. Xu, Energies 2022, 15, 8717.[5] H. F. Xu, X. Wang, Z. G. Shao, I. M. Hsing, J. Appl. Electrochem. 2002, 32, 1337–1340.

A new and robust MnCo1.9Sb0.1O4 spinel cathode for proton-conducting solid oxide fuel cells

As a cathode material for proton-conducting SOFCs (H–SOFCs), a novel MnCo1.9Sb0.1O4 (MCSO) spinel material was suggested. The MCSO material was effectively produced, and it demonstrated excellent phase stability at elevated temperatures and chemical stability against CO2 and H2O. Doping Sb into the MnCo2O4 (MCO) allowed for enhanced proton diffusion and surface exchange, as evidenced by electrical conductivity relaxation tests. In addition, an oxygen-vacancy-rich surface was developed for the MCSO material, resulting in the possibility of a high cathode oxygen reduction reaction activity. The MCSO material was examined in the H–SOFC application, and the fuel cell with an MCSO cathode attained a high power density of 1380 mW cm−2 at 700 °C. At 700 °C, the cell employing the Sb-free MCO cathode, which had a comparable cell microstructure to the MCSO cell, only obtained a peak power density of 836 mW cm−2. The higher cell performance resulted from the Sb-modified MCO cathode's increased catalytic activity. In addition, the MCSO cell displayed excellent operational stability under fuel cell operating conditions, indicating that MCSO is a novel and effective spinel cathode for H–SOFCs.

Time-dependent lateral diffusion in WO[formula omitted] thin films

We have studied the anomalous lateral diffusion process in thin tungsten trioxide films by optical means. The diffusion process seems to start at imperfections within the film a few seconds after the H+ ion intercalation begins, and progresses parallel to the surface of the film. We measured the mean square displacement of the diffusion front and used its time-dependence to calculate the instantaneous diffusion coefficient. The anomalous exponents are found to be 2.24 and 2.92 for 400 nm and 270 nm thick films, respectively. We explain the observed large diffusion coefficients and depth dependence of the expansion of the film by interfacial job-sharing diffusion of electrons and protons. Raman measurements were also carried out on virgin films, and on films after the lateral diffusion. Although the observed spectrum after the lateral diffusion is, in general, consistent with the literature for H+ intercalated films, we observe an additional strong band at 855 cm−1. This lateral diffusion process is observed to be irreversible; therefore, it has to be avoided in electrochromic switching devices based on WO3.

Proton transport through interfaces in nanophase-separation of hydrated aquivion membrane: Molecular dynamics simulation approach

We investigate the effect of temperature and hydration on the nanophase-separated structure and proton conductivity in Aquivion and Nafion membranes using molecular dynamics simulation method. By considering two different temperatures (298 and 353 K) and water contents (10 and 20 wt%), our study reveals that Nafion exhibits better nanophase separation and a more mature internal structure of the water phase compared to Aquivion, leading to facilitated proton dissociation and improved proton conduction through vehicular and hopping mechanisms. This study also identifies the formation of a hydronium-mediated bridge configuration that restricts vehicular mobility at low hydration, resulting in a decrease of the vehicular contribution to proton conduction. From quantitative evaluation of the extent of nanophase-separation using structure factor analysis, we find that Nafion has a shorter correlation length with greater concentration contrast in comparison to Aquivion. At high hydration conditions, the hopping mechanism dominates at low temperature while the vehicular mechanism is dominant at high temperature. At low hydration, the vehicular mechanism is significantly decreased due to hydronium-mediated bridge configurations. It is interesting to note that the proton conductivity in the Aquivion membrane is higher despite the Nafion membrane having a higher proton diffusion. We discover that the greater proton conductivity of Aquivion membrane is caused by its higher proton concentration. In general, our findings offer a fundamental knowledge of the connection between nanophase-separated structure and proton transport characteristics in Nafion and Aquivion systems under a range of temperature and hydration circumstances.

Proton/Mg2+ Co-Insertion Chemistry in Aqueous Mg-Ion Batteries: From the Interface to the Inner.

Co-insertion of protons happens widely and enables divalent-ion aqueous batteries to achieve high performances. However, detailed investigations and comprehensive understandings of proton co-insertion are scarce. Herein, we demonstrate that proton co-insertion into tunnel materials is determined jointly by interface derivation and inner diffusion: at the interface, hdrated Mg2+ has poor insertion kinetics, and therefore accumulates and hydrolyzes to produce protons; in the tunnels, co-inserted/lattice H2 O molecules block the Mg2+ diffusion while facilitate the proton diffusion. When monoclinic vanadium dioxide (VO2 (B)) anode is tested in Mg(CH3 COO)2 aqueous solution, the formation of Mg-rich solid electrolyte interphase on the VO2 (B) electrode and co-insertion of derived protons are probed; in the tunnels, the diffusion energy barrier of Mg2+ +H2 O is 2.7 eV, while that of the protons is 0.37 eV. Thus, protons dominate the subsequent insertion and inner diffusion. As a consequence, the VO2 (B) achieves a high capacity of 257.0 mAh g-1 at 1 A g-1 , a high rate retention of 59.1 % from 1 to 8 A g-1 , and stable cyclability of 3000 times with a capacity retention of 81.5 %. This work provides an in-depth understanding of the proton co-insertion and may promote the development of rechargeable aqueous batteries.

Proton/Mg2+ Co‐Insertion Chemistry in Aqueous Mg‐Ion Batteries: From the Interface to the Inner

AbstractCo‐insertion of protons happens widely and enables divalent‐ion aqueous batteries to achieve high performances. However, detailed investigations and comprehensive understandings of proton co‐insertion are scarce. Herein, we demonstrate that proton co‐insertion into tunnel materials is determined jointly by interface derivation and inner diffusion: at the interface, hdrated Mg2+ has poor insertion kinetics, and therefore accumulates and hydrolyzes to produce protons; in the tunnels, co‐inserted/lattice H2O molecules block the Mg2+ diffusion while facilitate the proton diffusion. When monoclinic vanadium dioxide (VO2(B)) anode is tested in Mg(CH3COO)2 aqueous solution, the formation of Mg‐rich solid electrolyte interphase on the VO2(B) electrode and co‐insertion of derived protons are probed; in the tunnels, the diffusion energy barrier of Mg2++H2O is 2.7 eV, while that of the protons is 0.37 eV. Thus, protons dominate the subsequent insertion and inner diffusion. As a consequence, the VO2(B) achieves a high capacity of 257.0 mAh g−1 at 1 A g−1, a high rate retention of 59.1 % from 1 to 8 A g−1, and stable cyclability of 3000 times with a capacity retention of 81.5 %. This work provides an in‐depth understanding of the proton co‐insertion and may promote the development of rechargeable aqueous batteries.

Ba0.9Co0.7Fe0.2Nb0.1O3-δ perovskite as promising cathode material for proton ceramic fuel cell

The protonic ceramic fuel cell (PCFC) is limited in performance by the delayed oxygen reaction on the cathode caused by low temperature. Herein, we investigate Ba0.9Co0.7Fe0.2Nb0.1O3-δ (BCFN), a cathode material with excellent electrocatalytic activity and structural stability. The electrical conductivity relaxation method was explored for the proton transport ability of BCFN material, which revealed a proton diffusion coefficient of 0.515 × 10−3 cm s−1 at 600 °C. To further enhance the proton conductivity of material and increase the reaction sites, a BCFN-BaCe0.7Zr0.1Y0.1Yb0.1O3−δ (BCZYYb) composite cathode was developed and its average thermal expansion coefficient value was lowered to 15.7 × 10−6 K−1 from 30 to 800 °C. At 700 °C, a single cell with a BCFN-BCZYYb cathode achieves a peak power density of 859 mW cm−2, and the Rp value is 0.05 Ω cm2. Furthermore, good durability of stable operation at 150 mA cm−2 for 100 h is obtained at 600 °C. These results imply that BCFN-BCZYYb could be an effective PCFC cathode.

Interfacial Disordering and Heterojunction Enabling Fast Proton Conduction.

The interfacial disorder is a general method to change the metal-oxygen compatibility and carrier density of heterostructure materials for ionic transport modulation. Herein, to enable high proton conduction, a semiconductor heterostructure based on spinel ZnFe2 O4 (ZFO) and fluorite CeO2 is developed and investigated in terms of structural characterization, first principle calculation, and electrochemical performance. Particular attention is paid to the interfacial disordering and heterojunction effects of the material. Results show that the heterostructure induces a disordered oxygen region at the hetero-interface of ZFO-CeO2 by dislocating oxygen atoms, leading to fast proton transport. As a result, the ZFO-CeO2 exhibits a high proton conductivity of 0.21 Scm-1 and promising fuel cell power output of 1070mWcm-2 at 510 °C. Based upon these findings, a new mechanism is proposed by focusing on the change of O-O bond length to interpret the diffusion and acceleration of protons in ZFO-CeO2 on the basis of the Grotthuss mechanism. This study provides a new strategy to customize semiconductor heterostructure to enable fast proton conduction.

Deep eutectic solvents based on N, N, N-trimethyl propylsulphonate ammonium hydrosulfate-urea as potential electrolytes for proton exchange membrane fuel cell

Deep eutectic solvents (DESs) have been synthesized by using N, N, N-trimethyl propylsulphonate ammonium hydrosulfate as the hydrogen bond acceptor (HBA) and urea as hydrogen bond donor (HBD) in capricious molar ratios. Fourier transform infrared spectrum, the proton nuclear magnetic resonance and carbon-13 nuclear magnetic resonance are employed to confirmed the chemical structures of N, N, N-trimethyl propylsulphonate ammonium hydrosulfate. The synthesized DESs are characterized by thermogravimetric analysis and Fourier transform infrared spectrum. The synthesized DESs exhibit excellent thermal stability, making them suitable electrolytes for proton exchange membrane fuel cell. The viscosity and conductivity of DESs are significantly affected by the molar ratio between HBD and HBA. The four samples are used as electrolytes to evaluate the fuel cell performance. The results indicate that the power density of the four samples decreases in the following order: DES with a molar ratio of HBA/HBD of 1:1 > DES with a molar ratio of HBA/HBD of 2:1 >N, N, N-trimethyl propylsulphonate ammonium hydrosulfate > DES with a molar ratio of HBA/HBD of 1:2. The DES with a molar ratio of HBA/HBD of 1:1 exhibits a significantly higher peak power density of 92.5 mW · cm−2 compared to the peak power density (48.5 mW · cm−2) observed without the addition of urea at 50 °C, while DES with a molar ratio of HBA/HBD of 1:2 displays a much lower peak power density of only 8.7 mW · cm−2 at 30 °C. The proton diffusion coefficient D is a critical factor that significantly impacts fuel cell performance. DESs as proton conducting media is a promising approach to improve cell performance in the proton exchange membrane fuel cell.

Anisotropic proton conduction in double-perovskite GdBaCo2O5.5

The proton-conductive properties of perovskite oxides have attracted attention for applications in sensors and neuromorphic devices. Recently, a unique two-dimensional proton conduction was theoretically predicted in the double-perovskite GdBaCo2O5.5 with a Gd/Ba order along the c-axis. To experimentally confirm the anisotropic proton conductivity, we prepared two types of GdBaCo2O5.5 epitaxial films with different crystal orientations: the films on NdGaO3(110) and SrTiO3(001) substrates had a Gd/Ba order along the in-plane and out-of-plane directions, respectively. Both the GdBaCo2O5.5 films were doped with protons via an electrochemical method under the same conditions at room temperature. From the reaction time dependence of the change in the lattice constants and proton depth profiles of the films, we found that the proton conductivity along the Gd/Ba order was slower than across it, which agreed well with theoretical calculations. The anisotropy of proton conductivity in GdBaCo2O5.5 probably originates from the BaO planes with large Ba2+ ions that hinder proton diffusion.