Over-humidification and condensation in polymer electrolyte fuel cells (PEFCs) can promote local flooding and performance losses, creating a need for simple and localized liquid water detection. In this study, copper interdigitated electrode (IDE) sensors on polyimide substrates are modified with electrochemically deposited polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) (PEDOT) coatings. The sensors are characterized using FTIR, contact angle measurements, optical microscopy, SEM/EDX, XPS, and defined droplet tests. PANI produces a comparatively compact and hydrophobic surface, whereas PEDOT forms a finer, more hydrophilic structure that promotes droplet spreading and water retention. All sensor types show rapid voltage responses to liquid water bridging, with bare copper providing the highest absolute sensitivity. Wet-dry transitions and an 24 h ex-situ PEFC-relevant humid gas protocol, comprising replicated cathode and anode side conditions, reveals distinct response characteristics. Bare copper exhibits a delayed, threshold-like voltage decrease and comparatively unstable baseline behaviour. PEDOT responds strongly to humidification but shows persistent low voltage states and slower recovery, consistent with greater water retention. PANI provides the most balanced performance, combining rapid response, controlled wetting, gradual and reversible signal evolution, and the most stable voltage behaviour within the investigated exposure window. Post-test XPS confirms the presence of oxidized copper species and coating-specific elemental signals, while also indicating that the polymer layers remain detectable after exposure. These results identify PANI as the more promising coating for adapting copper IDE sensors to localized condensation and over-humidification detection under the studied PEFC-relevant conditions.

Sulfur-depolarized electrolysis (SDE) is an interesting alternative for H2 production. Lower operational voltage (<1.2 V) and a valuable by-product offer an opportunity for economically competitive H2 production in sectors where traditional processes are not feasible or competitive. However, given its incipient state in development, several questions are yet to be answered to achieve stable, competitive operation. A definitive reaction mechanism for the anodic sulfur oxidation reaction has not been defined and therefore optimal properties for the diffusion media have not been established. In this study, the influence of various commercial gas diffusion layers (GDLs) on SDE performance and acid generation was systematically investigated. The choice of GDL was found to have a decisive impact on overall cell performance, in some cases determining whether stable operation was achievable. By optimizing the diffusion layer, current densities of 1.3 A cm-2 at 1.2 V were achieved, representing ≈30% improvement against state of the art. Based on observations during the study, a working hypothesis was proposed for the macroscale behavior of SDE during operation. These findings provide new insights into the anodic processes of SDE and identify critical parameters for developing efficient and durable electrochemical systems for low-voltage, economical hydrogen production.

High temperature proton exchange membrane fuel cells (HT-PEMFCs) are a carbon-neutral technology that can help overcome common low-temperature PEMFC issues such as high requirements for purity of the fuel or limited heat rejection at lower temperatures and enable a green transition in powering heavy-duty vehicles (HDVs). However, the higher operating temperature of up to 200 degrees C poses an additional challenge to the development of suitable and durable materials. The development of accelerated stress tests (ASTs) that can mimic real life applications is crucial to enable a time efficient investigation of new materials and to establish comparable material assessment standards across different laboratories. Here we present an AST that enables the investigation of new HT-PEMFC materials in HDV application related conditions and can be readily adapted to investigate individual cells in a stack. The proposed AST is based on realistic performance of HDFCVs across drive cycle data of the Trans-European Transport Network (TEN-T) and was generated with a real driving simulationbased approach using a multi-layered modeling framework integrating a heavy-duty vehicle with HT-PEMFC technology. In addition, we introduce a highly accelerated stress test (HAST) based on the same simulations with additional stressors to amplify degradation. We provide detailed information regarding the generation of the AST and the HAST as well as experimental data of both protocols being performed for 100 h at 180 degrees C with state-of-the-art HT-PEMFC materials to validate the testing procedure.

Novel, self-standing membranes based on chitosan (CS), incorporating N-doped reduced graphene oxide nano-ribbons (N-rGONR) and crosslinked with the naturally derived genipin (GEN), were developed. FTIR confirmed successful GEN reaction with CS and the introduction of N-rGONRs, which reduced the overall crystallinity while improving its mechanical properties. The comprehensive physicochemical and electrochemical properties, including ethanol permeability, alkali uptake, dimensional stability, ionic conductivity, and durability, were evaluated. Membrane performance was assessed within the single-cell module under practical operating conditions in an alkaline direct ethanol fuel cell (ADEFC). CS-based membranes containing 0.01 wt% N-rGONR achieved a maximum power density of 6.8 mW cm-2 at 57 degrees C with 1 M ethanol/1 M KOH, increasing to 17.7 mW cm-2 at 3 M ethanol/5 M KOH, surpassing a commercial reference membrane. Membranes containing either NrGONR or GEN showed superior performance in single-cell experiments; however, their combined addition demonstrated better retention of ionic conductivity over 14 days of exposure to simulated ADEFC operating conditions. This synergistic stabilisation effect of both components on CS, which when not modified completely degrades in prolonged exposure experiments, emphasises the potential of the newly developed CS-based membranes for alkaline direct ethanol fuel cell applications.

Carboxymethyl cellulose (CMC)-based solid polymer electrolytes (SPEs) have attracted significant attention as sustainable alternatives to conventional liquid electrolytes due to their biodegradability, non-toxicity, and excellent film-forming capability. However, pristine CMC suffers from inherent limitations, including low ionic conductivity, poor mechanical strength, and limited electrochemical stability. This systematic literature review comprehensively evaluates recent advances in CMC-based SPEs, focusing on the roles of lithium salts (e.g., LiCH3COO, LiClO4, LiI, LiBF4, and LiNO3) and functional additives, including plasticizers, ionic liquids, nanofillers, and cross-linking agents, in tailoring the physicochemical and electrochemical properties. The findings reveal that ionic conductivity can be significantly enhanced from ~10-7 to 10-2 S cm-1 through synergistic modifications that reduce crystallinity and promote segmental mobility. Electrochemical stability is improved by up to ~3.85 V with the incorporation of ionic liquids, while ion transference numbers approaching unity (t+ ≈ 0.96) indicate highly efficient Li+-dominated transport. Mechanical properties exhibit a trade-off between flexibility (elongation up to ~699%) and tensile strength (up to ~12.84 MPa), depending on the balance between plasticization and cross-linking. The degradation temperature is also strongly influenced by system composition, reaching ~508 °C in ionic liquid-modified systems. Overall, the performance of CMC-based SPEs is governed by the interplay between salt chemistry, polymer structure, and additive functionality. This review highlights key structure-property relationships and identifies critical research gaps, including salt-concentration optimization, long-term stability, and scalability, providing strategic insights for the rational design of high-performance, sustainable polymer electrolytes for next-generation energy storage applications.

Hydrogen sulphide, found in air, reformed hydrogen, and lunar water, poses a serious threat to platinum electrocatalysts, significantly shortening the lifespan of polymer electrolyte membrane fuel cells. This study examines how electrode fabrication methods influence contamination resistance. Two types of catalyst coated membranes (CCMs)-ultrasonically spray-coated and electrospun nanofibre-were fabricated, each with a platinum loading of 0.3 mg cm(-2) on both anode and cathode. Electron microscopy and Hg porosimetry revealed a porous fibre network in nanofibre CCMs, while less porous coated CCMs showed catalyst agglomerates. Both CCMs exhibited similar electrochemical surface areas (similar to 17 m(2)& centerdot;gPt(-1)), but nanofibre CCMs achieved a peak power density of 437 +/- 34 mW cm(-2), outperforming coated CCMs (252 +/- 13 mW cm(-2)). Impedance spectroscopy indicated significantly lower time-dependent resistances in nanofibre CCMs (265 +/- 10 m Omega cm(2)) versus coated ones (513 +/- 43 m Omega cm(2)). Under 2 ppm hydrogen sulfide exposure, nanofibre CCMs were more vulnerable to anode contamination due to faster contamination penetration, yet more resilient at the cathode, likely because of enhanced oxygen diffusion and in-operando sulphur oxidation. These results highlight the critical role of electrode structure in contamination behaviour and suggest that hybrid CCMs-combining coated anodes with nanofibre cathodes-may optimize both performance and durability in PEM fuel cells.

Despite its potential, sulphur depolarised electrolysis (SDE) technology remains in the early stages of development, its optimal operating conditions are not fully established and the utilization of catalysts other than Pt have not been assessed. In this study we investigate; in-situ, under a single cell configuration, followed by ex-situ characterisation using SEM/EDX imaging and SAXS analysis, the effects of temperature, alternative non-critical raw material catalysts, and asymmetrical catalyst loading. Temperature was found to have a pronounced effect on efficiency, with performance increase of similar to 1.6 A mgPt(-1) by changing from 20 degrees C to 80 degrees C under identical flow rate conditions. Based on a review of theoretical studies of the sulphur oxidation reaction, gold emerged as a particularly promising anodic catalyst. Among the catalyst loadings tested, the 0.1/0.3 mgPt cm(-2) (anode/cathode) configuration delivered the best performance, achieving >6.7 A mgMetal and 0.5 A cm(-2) at 1.2 V, a notable improvement over the 0.3 A cm(-2) achieved with the Pt-Pt configuration, while reducing platinum usage, a CRM, by 50%. These results advance the SDE process towards the target of 0.7 mA cm(-2), theoretically achieving 36.1 kWh/kg H-2 while widening the options regarding catalyst usage, shortening the gap to achieving competitive co-production of H-2 and H2SO4.

Proton exchange membrane water electrolysis is a promising technology for sustainable hydrogen production yet transferable diagnostics across systems, especially in early operation remain as a key challenge for a reproducible operation. Despite being an easily accessible metric, transient open circuit voltage behavior in proton exchange membrane water electrolysis remains less explored than in proton exchange membrane fuel cells. In this work, early post conditioning open circuit voltage behavior is evaluated as an empirical indicator of transient instability during operation. The results reveal clear differences between open circuit voltage behavior and subsequent operational performance for catalyst coated membranes incorporating nominally identical membranes from different manufacturers. These findings highlight the potential of simple diagnostic strategies for early-stage material assessment in proton exchange membrane water electrolysis, suggesting differences in manufacturing while exposing limitations in the reproducibility of the metric across nominally identical material and operational conditions. Additionally, material properties were investigated after conditioning step, using fluoride ion and total fluorine measurements as two closely related metrics and their potential link to open circuit voltage performance. No clear correlation between these metrics and open circuit voltage behavior was observed.

This review summarizes the development of electrospinning, including fibre patterning, scale up strategies, structure and performance relationships, energy device applications, and bibliometric analysis.

Hydrogen production performance was investigated using a biomass gasifier-integrated hydrogen production pilot plant, fabricated for the first time at the Hydrogen Energy Laboratory, BCSIR. Production of producer gas from wood chips, its cleaning, upgradation, drying, and hydrogen separation via PSA were conducted using the pilot configuration. The key challenge is to report the optimal H2 output and purity using this configuration. A 15 kWh, 60% efficient downdraft biomass gasifier generates 13.38 m3/h of producer gas (CO = 19%, H2 = 16.68%, CO2 = 13.05%, and CH4 = 2.1%) with the calorific value of 5.48 MJ/m3, which is subjected to a threestage cleaning process. WGS conversion ensures the concentrations of H2 and CO gases are 29%, 33%, 31% and 1.5%, 0.98% & 1.2%, respectively, at 300 degrees C, 350 degrees C & 400 degrees C, and steam/CO ratios of 2.5, 3.0, 3.5 & 4.0. Finally, the plant produces 98.6% (Vol %) hydrogen gas and stores it at 55 bar for further use.

Water management remains a critical challenge in polymer electrolyte fuel cells (PEFCs), as excessive liquid water accumulation can obstruct reactant transport, destabilize cell voltage, and reduce performance. In this work, the established liquid bridging principle of interdigitated electrodes is implemented using directly laser-written, uncoated laser induced graphene (LIG) electrodes for over-humidification detection under PEFC-relevant conditions. The resulting LIG-based moisture analyser (LIGMA) is fabricated by CO2 laser patterning of polyimide without masks or additional humidity sensitive coatings. Raman spectroscopy confirms graphitic carbon formation, while scanning electron microscopy reveals the characteristic porous and fibrous LIG morphology. Different IDE geometries are evaluated to determine the influence of finger spacing and active area on droplet response. The sensors show response times of 1-4 s, and the fine geometry reliably detects the smallest investigated droplet volume of 2 µl under the defined deposition protocol. This value is reported as the minimum experimentally tested and detected volume. The voltage response is interpreted as a coupled process involving liquid water bridging, capillary spreading and retention within the porous LIG network, and possible interfacial effects. During 100 h exposure to humidified hydrogen and air, the sensors remained electrically functional and showed no visible delamination, cracking, or pore collapse in the examined regions. Initial testing at the cathode outlet of an operating PEFC shows pronounced signal changes during extended outlet wetting. The results demonstrate the potential of directly patterned LIG IDEs as simple outlet side indicators for condensation and liquid water breakthrough in PEFC systems.

High temperature proton exchange membrane fuel cells (HT-PEMFCs) are a promising technology to power heavy duty vehicles (HDVs) as they can be operated with cheaper hydrogen due to the high operating temperature and need less heat exchangers compared to low temperature (LT-)PEMFCs because of the larger temperature gradient to the environment. Recently, new materials such as ion-pair based membranes have been developed to overcome phosphoric acid leaching that is limiting the lifetime of state-of-the-art phosphoric acid doped polybenzimidazole based membranes [1, 2]. Whereas for LT-PEMFCs many accelerated stress tests (ASTs) are available that help investigate the durability of new materials on an efficient timescale, standardized tests are widely missing for HT-PEMFCs. Here we present an AST protocol mimicking real life HT-PEMFCs operation [3]. This AST was generated with a multi-layered modeling framework that evaluated the performance of an HDV operated by an HT-PEMFC, incorporating realistic drive cycle data from the Trans-European Transport Network and. In this study, the developed AST is evaluated by performing 100 h ASTs of state-of-the-art HT-PEMFC materials in commercially relevant operating conditions. The presented AST protocol aims to support the scientific community and industry in establishing standardized testing procedures to facilitate the collaboration and development of new materials for HT-PEMFCs in HDV applications. Acknowledgement: This work was supported by the “Horizon Europe” program of the European Union under project MEAsureD (grant agreement No. 101101420). References: [1] A. Zucconi, J. Hack, R. Stocker, T. A. M. Suter, A. J. E. Rettie and D. J. L. Brett, Challenges and opportunities for characterization of high-temperature polymer electrolyte membrane fuel cells: a review, J. Mater. Chem. A, 2024, 12, 8014. DOI: 10.1039/d3ta06895a. [2] K.-S. Lee, J. S. Spendelow, Y.-K. Choe, C. Fujimoto and Y. S. Kim, An operationally flexible fuel cell based on quaternary ammonium-biphosphate ion pairs, Nature Energy, 2016, 1, 16120. DOI: 10.1038/NENERGY.2016.120. [3] MEAsureD Deliverable Report D2.4, Graz University of Technology, Graz, 2024. [Online]. Available: https://measured-horizon.eu/resources/.

Anion exchange membranes (AEMs) have received significant attention as cost-effective electrolytes for alkaline fuel cells due to their potential to enhance electrochemical performance while replacing expensive proton exchange membranes. In this work, composite AEMs were fabricated from chitosan (CS), poly(vinyl alcohol) (PVA), and poly(diallyldimethylammonium chloride) (PDDA) through a solution casting method followed by chemical crosslinking using glutaraldehyde as a crosslinking agent. Chitosan served as the main biopolymer matrix, PVA improved film-forming ability and mechanical strength, while PDDA introduced quaternary ammonium groups that facilitated hydroxide ions transport. The prepared membranes were characterized by water uptake (WU), and hydroxide ion conductivity (σ). FTIR and SEM analyses confirmed the successful incorporation of PDDA and strong intermolecular interactions among polymer components, resulting in a dense and homogeneous structure. Increasing PDDA concentration led to enhanced ionic transport, with the CPP–0.20 membrane achieving the highest hydroxide conductivity of 21 mS cm−1 at room temperature.

Over‐humidification is a critical challenge to the performance and durability of polymer electrolyte fuel cells (PEFCs). This review evaluates current methods for detecting and quantifying over‐humidification, focusing on simulation, imaging, and sensor technologies. Each method is assessed based on five key criteria: precision, sensitivity, real‐time capability, interpretation complexity, and validation strength. Physically grounded modeling approaches such as computational fluid dynamics and the lattice Boltzmann method offer high accuracy but are computationally demanding. Imaging techniques, including neutron imaging and magnetic resonance imaging, provide valuable insight and validation but face limitations regarding scalability and real‐time application. Sensor technologies, from commercial sensors to artificial intelligence–enhanced and nanostructured platforms, enable real‐time monitoring but require improved robustness and validation under operando conditions. By comparing these techniques individually and collectively, this review identifies promising hybrid strategies and outlines research priorities for achieving intelligent, real‐time water management in PEFCs.

This review article addresses the fundamental theories of the ordered catalyst layer in PEMFC and its future development.

This study investigates the use of mixed ionic electronic conductors (MIECs) in ceramic structures to enhance green hydrogen storage through Chemical Looping Hydrogen (CLH) technology. A novel method integrates Yttria-stabilized zirconia (YSZ) into a ceramic foam matrix, significantly improving oxygen exchange capacity (OEC) and specific hydrogen productivity (SHP) by 30-40% with YSZ3 and 10-15% with YSZ8. Over 150 cycles, YSZ8 show the best pressure behavior in the fixed-be and doubling the storage capacity compared to conventional materials like pure ZrO2. The study also reveals the superior cyclic stability of these materials, maintaining over 80% efficiency across numerous cycles. These advancements not only support safer, more cost-effective hydrogen storage and transportation but also demonstrate strong potential for industrial scalability, crucial for future energy systems and COQ-neutral technologies. The structured oxygen carriers could revolutionize hydrogen storage by offering a scalable, efficient solution that meets the demands of modern energy infrastructures.

Alkaline Polymer Electrolyte Fuel Cells (APEFCs) have emerged as a promising candidate for clean energy production. Anion exchange membrane (AEM) is an essential element of alkaline polymer electrolyte fuel cells for its role in facilitating hydroxide ion conduction. The objective of this study is to investigate the effect of a glutaraldehyde-based crosslinker solution on the performance of anion exchange membranes (AEMs) fabricated using quaternary ammonium poly (vinyl alcohol) (QPVA) as the backbone polymer and polyquaternium-7 as the second polymer. The introduction of a glutaraldehyde-based crosslinking agent was purposed to enhance membrane stability and reduce excessive swelling. The study evaluates the impact of varying glutaraldehyde concentrations on membrane performance. FTIR analysis confirms the presence of key functional groups of QPVA, polyquaternium-7, and the crosslinking agent. SEM images reveal that the membranes demonstrate dense and homogeneous physical structure. The results show that water uptake, swelling degree, ion exchange capacity (IEC), and hydroxide conductivity are influenced by the concentration of the glutaraldehyde solution. The QP-GA-13 AEM exhibited the best overall performance, achieving the highest tensile strength of 31.1 MPa and the highest hydroxide ion conductivity of 4.15 mS cm⁻¹ at 70°C. In single-cell tests, this membrane delivered a maximum power density of 85 mW cm⁻² and a current density of 350 mA cm⁻² at 80°C under humidified oxygen conditions.

The porous transport layer (PTL) in proton exchange membrane water electrolysis (PEMWE) accounts for approximately 17–25% of total stack cost and its durability and structural stability are crucial for system performance and lifetime. Due to the harsh conditions on the anode, corrosion-resistant titanium fiber or sintered PTLs are required. However, the mechanical behavior of these materials under compression and in particular under varying conditions, remains insufficiently understood.In this study, a mechanistic understanding of compression-induced performance hysteresis in titanium PTLs through in-situ stress tests and ex-situ mechanical and structural characterization is acquired. Fiber-based and sintered Ti-PTLs, with and without Pt coating, were subjected to cyclic compression during PEMWE operation to evaluate the evolution of contact behavior, performance, and morphology. Results show a compression-induced performance hysteresis and irreversible deformation and degradation. Fiber PTLs show greater initial performance but are more prone to permanent compaction, while sintered PTLs maintain structural rigidity but exhibit less adaptive contact formation. Platinized PTLs generally demonstrate higher resistance to mechanical fatigue.This work provides practical guidance for PEMWE stack assembly and PTL selection and thereby enables the definition of compression boundaries and PTL architecture recommendations. This allows to minimize mechanical fatigue and extend PEMWE operational durability, therefore supporting more cost-effective and robust clean hydrogen production.

Anion exchange membrane fuel cells (AEMFCs) have garnered significant attention for their potential to advance fuel cell technology. In this study, we developed and characterized anion exchange membranes (AEMs) composed of quaternized poly(vinyl alcohol) (QPVA) electrospun nanofiber mats with poly(acrylamide-co-diallyldimethylammonium chloride) (PAADDA) as a matrix filler for interfiber voids. The objective was to investigate the effect of varying PAADDA concentrations as a matrix filler for interfiber voids on the structural, mechanical, and electrochemical properties of QPVA-based electrospun AEMs. Membranes with various concentrations of PAADDA were fabricated and extensively characterized using FTIR, SEM, tensile strength, water uptake, swelling degree, ion exchange capacity (IEC), and hydroxide ion conductivity (σ). FTIR confirmed the successful incorporation of PAADDA into the membrane structure, while SEM images showed that PAADDA effectively filled the voids between the QPVA fibers, resulting in denser membranes. The results indicated that the eQPAD5.0 membrane, with the highest PAADDA content, exhibited the best overall performance. The incorporation of PAADDA into QPVA-based electrospun AEMs significantly enhanced their mechanical strength, achieving a tensile strength of 23.9 MPa, an IEC of 1.25 mmol g-1, and hydroxide conductivity of 19.49 mS cm-1 at 30 °C and 29.29 mS cm-1 at 80 °C, making them promising candidates for fuel cell applications.

This work investigates the impact of iron-based oxygen carriers (OCs) on green hydrogen production using a fixed-bed chemical looping (CL) process, aiming for industrial scalability. We conducted a comprehensive material screening of OCs comprising Fe2O3 with support materials (Al2O3, TiO2, ZrO2) at an 80/20 wt.-% ratio. Focus was placed on ZrO2, pure and doped with CaO, MgO, and Y2O3, to examine their effects on redox efficiency and hydrogen production. Notably, ZrO2 doped with MgO and Y2O3 achieved a specific hydrogen production over 12 molH2/kgOC at a small scale, attributed to chemical inertness and porous morphology, enhancing cyclic stability over traditional TiO2 and Al2O3 supports. Large-scale testing of the most promising OC compositions in a 250 g fixed-bed reactor for 100 cycles revealed that doping ZrO2 with Y2O3 not only prevents phase transitions but also ensures higher cyclic stability among tested OCs. Our findings underscore the critical role of microscopic phenomena in the CL process's efficiency and introduce a novel approach for designing environmentally friendly OCs for effective hydrogen production.