Efficient Proton Research Articles

Insights Into the Thermal Stability and Proton Transport Mechanism of PTFE‐Nafion Composite Membranes

ABSTRACTThe controllable design of proton exchange membranes (PEMs) with outstanding temperature resistance and efficient proton conduction is essential for high‐temperature PEM fuel cells. In this study, a polytetrafluoroethylene (PTFE)‐Nafion composite PEM was prepared using immersion and high‐temperature heat treatment methods. To understand the thermal stability, the glass transition temperatures of the PTFE‐Nafion and Nafion membranes were tested using static thermomechanical analysis. The PTFE‐Nafion membrane had a higher glass transition temperature than the Nafion membrane. In terms of the microstructure, the PTFE‐Nafion composite membrane exhibited a slightly larger ion domain structure than the Nafion membrane, and the first scattering peak of the PTFE‐Nafion composite membrane appeared at q ≈ 0.018 nm−1, while the pure Nafion membrane peak was located at q ≈ 0.022 nm−1. The PTFE‐Nafion composite membrane also exhibited higher proton conductivity than the Nafion membrane, and the activation energy of the Nafion membrane was approximately 3.5 times higher than that of the PTFE‐Nafion composite membrane. These results demonstrated the difference in proton transport mechanism for the PTFE‐Nafion composite and pure membranes, which may help guide the rational design of PEMs for fuel cells operating in high‐temperature and low‐humidity environments.

Unveiling exceptional conduction mechanism and high proton conductivity in amorphous electrolyte for advanced ceramic fuel cells

The requirement of high ion conductive material working at low temperatures is highly demanding in fuel cells. This study explains a groundbreaking advancement in ceramic fuel cells by exploring the potential of amorphous Sm0.3Al0.7-oxide and the proton conduction mechanism of amorphous oxides. Opposite to conventional crystalline electrolytes, amorphous electrolytes showed superior ion conduction. To study the detailed mechanism of ion conduction, amorphous Sm0.3Al0.7-oxide was selected which exhibited an exceptional proton conductivity of 0.17 S/cm and a power density of 1100 mW/cm2 at 550 °C, significantly surpassing traditional electrolyte materials. Using advance characterization techniques, a new approach has been proposed to provide the reasons for the high conductivity of amorphous materials, which entails a complete mechanism that describes how disordered structure and disoriented grain boundaries facilitate efficient proton conduction by reducing energy barriers and enhancing ionic mobility. Also, it has been described how the high enthalpy and the high energy state of amorphous materials are suitable for enhancing proton conduction. This study aims to clarify why amorphous materials are promising candidates for future fuel cell applications, facilitating significant advancements in SOFC and PCFC technologies and paving the way for more efficient and sustainable energy solutions.

Advanced Iridium Catalysts on Multi-porous Tantalum Oxide Supports for Efficient Proton Exchange Membrane Water Electrolysis

Advanced Iridium Catalysts on Multi-porous Tantalum Oxide Supports for Efficient Proton Exchange Membrane Water Electrolysis

Flux Synthesis of Robust Polyimide Covalent Organic Frameworks with High-Density Redox Sites for Efficient Proton Batteries.

Aqueous proton batteries are attracting increasing attention in the large-scale next-generation energy storage field. However, the electrode materials for proton batteries often suffer from low specific capacity and unsatisfactory cycle durability. Herein, we synthesize two highly crystalline and robust polyimide covalent organic frameworks (COFs) through a solvent-free flux synthesis approach with benzoic acid as a flux and catalyst. The as-synthesized COFs possess enriched redox-active sites for proton storage and intrinsic Grotthuss proton conduction, rendering them ideal candidates for proton electrode materials. The optimal COF electrodes achieve a high specific capacity of 180 mAh/g at 0.1 A/g, among the highest COF-based proton batteries, and exhibit an outstanding rate capability of up to 100 A/g and long-term cycling stability with capacity retention of 99% after 5000 cycles at 5 A/g. The assembled full cells deliver a specific capacity of 150 mAh/g at 0.2 A/g with a maximum energy density of 72 Wh/kg and a maximum supercapacitor-level power density of 64 kW/kg, surpassing all reported COF-based systems. This work paves a new avenue for the design of electrode materials for aqueous proton batteries with high energy density, power density, rate capability and long-term cycling stability.

Effective Proton Conduction in Quasi-Solid Zinc-Manganese Batteries via Constructing Highly Connected Transfer Pathways.

Elusive ion behaviors in aqueous electrolyte remain a challenge to break through the practicality of aqueous zinc-manganese batteries (AZMBs), a promising candidate for safe grid-scale energy storage systems. The proposed electrolyte strategies for this issue most ignore the prominent role of proton conduction, which greatly affects the operation stability of AZMBs. Here we report a water-poor quasi-solid electrolyte with efficient proton transfer pathways based on the large-space interlayer of montmorillonite and strong-hydration Pr3+ additive in AZMBs. Proton conduction is deeply understood in this quasi-solid electrolyte. Pr3+ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α-MnO2 cell could achieve a high specific capacity of 433 mAh g-1 at 0.4 mA cm-2 and an excellent stability up to 800 cycles with a capacity retention of 92.2% at 0.8 mA cm-2 in such water-poor quasi-solid electrolyte for the first time. Ah-scale pouch cell with mass loading of 15.19 mg cm-2 sustains 100 cycles after initial activation, which is much better than its counterparts. Our work provides a new path for the development of zinc metal batteries with good sustainability and practicality.

Long-Range Proton Channels Constructed via Hierarchical Peptide Self-Assembly.

The quest to understand and mimic proton translocation mechanisms in natural channels has driven the development of peptide-based artificial channels facilitating efficient proton transport across nanometric membranes. It is demonstrated here that hierarchical peptide self-assembly can form micrometers-long proton nanochannels. The fourfold symmetrical peptide design leverages intermolecular aromatic interactions to align self-assembled cyclic peptide nanotubes, creating hydrophilic nanochannels between them. Titratable amino acid sidechains are positioned adjacent to each other within the channels, enabling the formation of hydrogen-bonded chains upon hydration, and facilitating efficient proton transport. Moreover, these chains are enriched with protons and water molecules by interacting with immobile counter ions introduced into the channels, increasing proton flow density and rate. This system maintains proton transfer rates closely resembling those in natural protein channels over micrometer distances. The functional behavior of these inherently recyclable and biocompatible systems opens the door for their exploitation in diverse applications in energy storage and conversion, biomedicine, and bioelectronics.

Effective Proton Conduction in Quasi‐Solid Zinc‐Manganese Batteries via Constructing Highly Connected Transfer Pathways

Elusive ion behaviors in aqueous electrolyte remain a challenge to break through the practicality of aqueous zinc‐manganese batteries (AZMBs), a promising candidate for safe grid‐scale energy storage systems. The proposed electrolyte strategies for this issue most ignore the prominent role of proton conduction, which greatly affects the operation stability of AZMBs. Here we report a water‐poor quasi‐solid electrolyte with efficient proton transfer pathways based on the large‐space interlayer of montmorillonite and strong‐hydration Pr3+ additive in AZMBs. Proton conduction is deeply understood in this quasi‐solid electrolyte. Pr3+ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α‐MnO2 cell could achieve a high specific capacity of 433 mAh g–1 at 0.4 mA cm–2 and an excellent stability up to 800 cycles with a capacity retention of 92.2% at 0.8 mA cm–2 in such water‐poor quasi‐solid electrolyte for the first time. Ah‐scale pouch cell with mass loading of 15.19 mg cm–2 sustains 100 cycles after initial activation, which is much better than its counterparts. Our work provides a new path for the development of zinc metal batteries with good sustainability and practicality.

Water Status Detection Method Based on Water Balance Model for High-Power Fuel Cell Systems

With the gradually accelerating pace of global decarbonization, highly efficient and clean proton exchange membrane fuel cells (PEMFCs) are considered to be an energy solution for the future. During the operation of a fuel cell, it is necessary to keep the internal proton exchange membrane in a good state of hydration, so an appropriate method of detecting the hydration state is essential. At present, fuel cell systems are rapidly developing towards high power, but methods for detecting the hydration state of high-power fuel cell systems are still relatively lacking. Therefore, this paper studies the hydration state of high-power fuel cell systems and builds a condensation tail-gas water collection device for calculating the water flow out of a fuel cell system, deriving the hydration status inside the high-power fuel cell system. To verify the proposed water balance model, a series of experiments were conducted based on controlled variables such as working temperature, air metering ratio, and load current. Experiments were conducted on a 100 KW fuel cell system to collect water flow from the fuel cell system. Finally, based on the experimental data, the change rate of the internal water content of the fuel cell system under different conditions was calculated. The results show that, under the same load current, as the working temperature and air metering ratio increase, the change rate of the internal water content of the fuel cell system gradually decreases. Therefore, at low power, it is necessary to maintain an appropriate working temperature, while at high power, maintaining an appropriate air metering ratio is more important.

Resonance-Assisted Self-Doping in Robust Open-Shell Ladder-Type Oligoaniline Analogues.

A novel resonance-assisted self-doping mechanism has been demonstrated in ladder-type oligoaniline-derived organic conductors. The new class of compounds has a unique structure incorporating acidic phenolic hydroxyl groups into the ladder-type cyclohexadiene-1,4-diimine core, enabling efficient resonance-assisted proton transfer and electronic doping without the need for external dopants. Mechanistic and computational studies confirm the open-shell, zwitterionic nature of the self-doped state and the significant role played by the dielectric environment. This new self-doping mechanism allows for higher stability and durability in the material's electronic performance. The self-doped form retains durability under harsh conditions and maintains its properties over extended periods of time.

A strong metal-support interaction strategy for enhanced proton-coupled electron transfer and promoted photocatalytic H2O2 production in pure water

Proton-coupled electron transfer (PCET) is a key factor in determining the H2O2 production efficiency from oxygen reduction reaction (ORR) or direct H2/O2 reaction, which usually requires the aid of proton donors including alcohols. Here, we report a strong metal-support interaction (SMSI) strategy to facilitate the PCET process of a typical Pd/TiO2 photocatalyst for photocatalytic ORR into H2O2 production in pure water. Compared to conventional Pd/TiO2 photocatalysts, the Pd/TiO2 photocatalyst with SMSI between Pd and TiO2 (Pd/TiO2-850H) promotes photocatalytic H2O2 production in pure water by 4.21-fold, which can be ascribed to that the SMSI simultaneously promotes the H2O dissociation and the photogenerated charge transfer from TiO2 to Pd catalyst, enabling highly efficient proton transfer to be participated into converting •O2- to H2O2. Moreover, the formation of TiO2-x overlayer caused by SMSI suppresses the H2O2 decomposition and stabilizes Pd NPs, finally achieving an H2O2 production rate of 4.10 mmol g−1 h−1, which surpasses most metal/TiO2 photocatalytic system.

Development of an algorithm for proton dose calculation in magnetic fields.

The advantages of proton therapy can be further enhanced with online magnetic resonance imaging (MRI) guidance. One of the challenges in the realization of MRI-guided proton therapy (MRPT) is accurately calculating the radiation dose in the presence of magnetic fields. This study aims to develop an efficient and accurate proton dose calculation algorithm adapted to the presence of magnetic fields. An analytical-numerical radiation dose calculation algorithm, Proton and Ion Dose Engine (PRIDE), was developed. The algorithm combines the pencil beam algorithm (PBA) with a novel iterative voxel-based ray-tracing algorithm. The new ray-tracing method uses fewer assumptions and ensures broader applicability for proton beam trajectory prediction in magnetic fields, and has been compared to Wolf's method and Schellhammer's method. The accuracy of PRIDE algorithm was validated on three phantoms and two practical plans (one single-field water plan and one prostate tumor plan) in different magnetic field strengths up to 3.0 T. The validation was performed by comparing the results against the Monte Carlo (MC) simulations, using the global gamma index criteria of 2%/2mm and 3%/3mm with a 10% threshold. PRIDE showed good agreement with MC in homogeneous and slab heterogeneous phantom, achieving gamma passing rates (%GPs) above 99% for 2%/2mm criteria when magnetic field strength is not greater than 1.5 T. Although the agreement decreased for scenarios involving high proton energy (240 MeV) and strong magnetic field (3.0 T), the 2%/2mm %GPs still remained above 98%. In lateral heterogeneous phantom, the accuracy of PRIDE decreased due to the PBA's limitation. For the two practical plans in different magnetic fields, %GPs exceeded 98% and 99% for 2%/2mm and 3%/3mm criteria, respectively. PRIDE can perform efficient and accurate proton dose calculation in magnetic fields up to 3.0 T, and is expected to work as a useful tool for proton dose calculation in MRPT.

Anisotropic Superprotonic Conduction in a Layered Single-Component Hydrogen-Bonded Organic Framework with Multiple In-Plane Open Channels.

Hydrogen-bonded organic frameworks (HOFs) are promising proton conductive materials because of their inherent and abundant hydrogen-bonding sites. However, most superprotonic-conductive HOFs are constructed from multiple components to enable favorable framework architectures and structural integrity. In this contribution, layered HOF-TPB-A3 with a single component is synthesized and exfoliated. The exfoliated nanoplates exhibited anisotropic superprotonic conduction, with in-plane proton conductivities reaching 1.34×10-2 S cm-1 at 296 K and 98% relative humidity (RH). This outperforms the previously reported single-component HOFs and is comparable with the state-of-the-art multiple-component HOFs. The high and anisotropic proton conductive properties can be attributed to the efficient proton transport along multiple open channels parallel to their basal planes. Moreover, an all-solid-state (ASS) proton rectifier device is demonstrated by combining HOF-TPB-A3 and a hydroxide ion-conducting layered double hydroxide (LDH). This work suggests that single-component HOFs with multiple open channels offer more opportunities as versatile platforms for proton conductors, making them promising candidates for conducting media in protonic devices.

Synergistic Engineering of Dopant and Support of Ru Oxide Catalyst Enables Ultrahigh Performance for Acidic Oxygen Evolution

AbstractActive and robust electrocatalysts for acidic oxygen evolution reaction (OER) are of crucial importance for efficient proton exchange membrane water electrolyzer (PEM‐WE). Ruthenium (Ru) oxide has attracted considerable attention due to its high activity. However, the unsatisfying stability of Ru oxide in acidic OER environments hinders the application. Here, Ce‐doped RuO2 nanoparticles are designed and supported on Co─N─C material (Ce@RuO2/CoNC) for acidic OER. It is demonstrated that Ce@RuO2/CoNC delivers a super low overpotential of 150 mV and an excellent stability of 1000 h at 10 mA cm−2, outperforming most previously reported Ru‐based catalysts. The mass activity is estimated as 2365.5 AgRu−1 at 1.5 V (vs RHE), representing ≈2× advance compared to the best prior study. Furthermore, applied in a single‐cell PEM‐WE device, it can steadily operate for 1000 h at 200 mA cm−2. The studies show that Ce‐doping and Co─N─C support synergistically enhance the activity and stability of Ru oxide by optimizing the free energies of OER intermediates and suppressing the dissolution of Ru.

Enhancing H+ conduction through glycolic acid-doped alginate-PVA based biopolymer electrolytes

This study investigates the development of a biopolymer blend electrolyte composed of alginate and poly (vinyl alcohol) (PVA), doped with glycolic acid (GA) to enhance H+ conductivity. The addition of GA significantly impacts the biopolymer blend's physicochemical properties and ionic conduction performance. Fourier transform infrared (FTIR) spectroscopy verified the intricate interactions and hydrogen bonding between the alginate-PVA matrix and GA. The addition of GA was shown to increase the amorphous phase, as observed through X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. This increase in the amorphous phase was found to enhance the thermal stability. Impedance analysis demonstrated a significant increase in ionic conductivity from approximately ∼10⁻⁸ S cm⁻1 for the undoped blend to 3.45 × 10⁻⁵ S cm⁻1 with 30 wt% GA (sample GA-30). The enhanced H+ conduction behaviour was consistent across various temperatures, adhering to the Arrhenius rule. These findings suggest that the alginate-PVA-GA system is a promising candidate for efficient proton transport applications.

Characterization of Porous Transport Layers Towards the Development of Efficient Proton Exchange Membrane Water Electrolysis

AbstractThe current goals for implementing the hydrogen economy have highlighted a need to further optimize water‐splitting technologies for clean hydrogen production. Proton exchange membrane water electrolysis (PEMWE) is a leading technology, but further optimizations of anode materials including the porous transport layer (PTL) and the adjacent catalyst layer (CL) are required to increase overall cell performance and reduce cost. This literature review describes advances in PTL development and characterization, highlighting early PTL characterization work and most common methods including capillary flow porometry and mercury intrusion porometry, optical imaging, neutron and x‐ray radiography, and x‐ray computed tomography. The article also discusses PTL protective coatings and their characterizations, focusing on platinum group metal (PGM)‐based coatings, alternative non‐PGM‐based coatings, post‐treated PTLs, and investigations into thin PGM‐based coatings. Furthermore, it highlights the integration of the PTL and the adjacent CL along with associated characterization challenges. Lastly, this review discusses future developments in the characterization needed to improve PEMWE's performance and long‐term durability are discussed.

A 3D open-framework amino acid templated cerium phosphite-oxalate showing proton conductive property

Using L-histidine as template, a three-dimensional (3D) open-framework cerium phosphite-oxalate, Ce2(H2O)2(H2PO3)2(C2O4)3·C6H11N3O2·H2O (1), has been synthesized under hydrothermal condition. Interestingly, it is the first example of lanthanide phosphite-oxalate with amino acid as the template. Compound 1 shows 3D framework with 8-, 12- and 20-ring channels and has a mog Moganite topology. A large amount of free water molecules and histidine cations are located in the channels of 1, which are favorable to the efficient proton transfer. Correspondingly, compound 1 displays temperature and humidity dependent proton conductivity with the highest value of 3.67 × 10−4 S cm−1 at 75 °C and 98 % RH.

Superprotonic Conductivity by Synergistic Blending of Coordination Polymers with Organic Polymers: Fabrication of Durable and Flexible Proton Exchange Membranes.

Creation of an efficient and cost-effective proton exchange membrane (PEM) has emerged as a propitious solution to address the challenges of renewable energy development. Coordination polymers (CPs) have garnered significant interest due to their multifunctional applications and moldability, along with long-range order. To leverage the potential of CPs in fuel cells, it is essential to integrate microcrystalline CPs into organic polymers to prepare membranes and avoid grain boundary issues. In this study, we designed and synthesized CPs containing imidazole and sulfonate moieties via gel-to-crystal transformation. The integration of CPs into the PVDF-PVP matrix resulted in superprotonic conductivity in the order of 10-2 S cm-1 at room temperature (30 °C) and 98 % RH. The proton conductivity achieved with CP-integrated composite membrane was 4.69×10-2 S cm-1 at 80 °C and 98 % RH, the highest among all CP/MOF-integrated PVDF-PVP membranes under hydrous conditions. The excellent compatibility of CPs with PVDF-PVP produced highly flexible membranes with superior mechanical, chemical, and thermal stability. About 25 times higher proton conductivity value was achieved with membrane, compared to intrinsic CPs, at RT and 98 % RH. Thus, we present a cost-effective CP-integrated mixed-matrix membrane with superprotonic conductivity and long-term durability for cutting-edge fuel cell development.

Binder-enhanced reversible photochromic films by tungsten oxide hybrid composites for advanced applications

In this study, we developed binder-enhanced reversible photochromic tungsten oxide (WO3) films for advanced applications. Expanding on previous research, we used tungsten oxide hybrid composites as the base material and incorporated various binders, specifically polyethylene glycol (PEG), polysorbate 80 (PS 80), and carboxymethyl cellulose (CMC), to evaluate their effects on reversible photochromic reactions. Our experiments demonstrated that the inclusion of CMC significantly improved the photochromic properties and exhibited the fastest reversible reactions when compared to PEG and polysorbate 80. This enhancement is attributed to the high density of hydroxyl groups and the network structure of CMC, which facilitate efficient proton transfer and oxygen permeability, both crucial for the reoxidation process in WO3. Density functional theory (DFT) calculations supported these findings by indicating that CMC has a suitable bandgap and electron mobility, which enhance charge injection and transport. Additionally, the fabricated films showed consistent and stable performance under both heat treatment and natural ambient conditions. These results underscore the potential of CMC as an effective binder for developing high-performance, reversible photochromic films suitable for applications in smart windows, displays, and optoelectronic devices.

Adipic acid-mediated hydrogen bonding network allocation for efficient proton conduction in water-stabilized lamellar MOF membranes

The poor water-stability and cross-layer proton transfer property pose a challenge to the lamellar metal–organic frameworks (MOFs) membrane when acting as a promising proton exchange membrane. Herein, we report an adipic acid-mediated strategy to improve the water-stability and the cross-layer proton conductivity of CuTCPP lamellar MOF membrane, which achieves a maximum power density and current density of 112.6 mW cm−2 and 424.4 mA cm−2, respectively. Adipic acid with extra functional groups (–PO3H2, –COOH) stably bridges the adjacent crystal layers via the terminal carboxylic acid anchoring Cu sites. In particular, the extra functional groups introduced into the adipic acid regulate the allocation of hydrogen bonding networks in an umbrella-shape around adipic acid with copper-porphyrin structures as external margin, enriching the coherence of hydrogen bonding network on the proton transport path. Benefiting from the regular pore structure of MOF, the optimized hydrogen bonding networks in adjacent crystal layers construct a more abundant through-plane transfer pathway. The resultant through-plane proton conductivities of CuTCPP-PO3H2/–COOH membranes are up to 108/89 mS cm−1 at 80 °C and 100 % RH, which is ∼ 6-fold higher than that of the pristine CuTCPP membrane (13 mS cm−1), with a conductivity attenuation of < 5 % during a humidity cycling test for 12 times.

Rough-surfaced polybenzimidazole membranes incorporating sulfonated porous aromatic frameworks for simultaneous enhancement of proton conduction and membrane electrode assembly optimization

The interface between the proton exchange membrane (PEM) and the catalyst layer (CL) has a substantial impact on the performance of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). However, studies on the interface in HT-PEMFCs have been rarely reported. In this work, an effective strategy to mitigate interface problems was designed. A rough-surfaced membrane was successfully constructed by depositing high-surface-area sulfonated porous aromatic frameworks (SPAFs) in poly[2,2′ −(p-oxydiphenylene)-5,5′ −benzimidazole (OPBI) to achieve a dual goal. The catalyst was sprayed on the rough-surfaced side of the composite membranes, and the surface area was significantly increased. Meanwhile, an efficient proton transport pathway within the rough-surfaced membrane was constructed based on hydrophilic nanochannels in SPAFs. As a result, a substantial increase of 1.7 times in the electrochemical surface area (ECSA) of the membrane electrode assembly (MEA) was achieved relative to that of a flat membrane. Compared to a pristine OPBI membrane, the membrane with a high content of 20 wt% SPAFs exhibits a 236% increase in proton conductivity at 170 °C and a considerable 1.82-fold enhancement in fuel cell performance under analogous circumstances. This strategy, which simultaneously enhances the proton conductivity of the membrane and strengthens the interface between the membrane and the catalyst layer, provides a new approach to improving the performance of HT-PEMFC.