Anion exchange membrane fuel cells have unique advantages and are thus gaining increasing attention. Poly(vinyl alcohol) (PVA) is one of the potential polymers for the development of anion exchange ...membranes. This review provides recent studies on PVA-based membranes as alternative anion exchange membranes for alkaline fuel cells. The development of anion exchange membranes in general, including the types, materials, and preparation of anion exchange membranes in the last years, are discussed. The performances and characteristics of recently reported PVA-based membranes are highlighted, including hydroxide conductivity, water uptake, swelling degree, tensile strength, and fuel permeabilities. Finally, some challenging issues and perspectives for the future study of anion exchange membranes are discussed.
Anion exchange membranes (AEMs) contribute significantly to enhance the performance and efficiency of alkaline polymer electrolyte fuel cells (APEFCs). A sequence of composite anion exchange ...membranes (AEMs) consisting of poly(vinyl alcohol) (PVA), poly(diallyldimethylammonium chloride) (PDDA), and nano-zirconia (NZ) has been prepared by a solution casting technique. The effect of zirconia mass ratio on attribute and performance of composite AEMs was investigated. The chemical structures, morphology, thermal, and mechanical properties of AEMs were characterized by FTIR, SEM, thermogravimetric analysis, and universal testing machine, respectively. The performance of composite AEMs was verified using water uptake, swelling degree, ion-exchange capacity, and OH
conductivity measurement. The nano-zirconia was homogeneously dispersed in the PVA/PDDA AEMs matrix. The mechanical properties of the composite AEMs were considerably enhanced with the addition of NZ. Through the introduction of 1.5 wt.% NZ, PVA/PDDA/NZ composite AEMs acquired the highest hydroxide conductivity of 31.57 mS·cm
at ambient condition. This study demonstrates that the PVA/PDDA/NZ AEMs are a potential candidate for APEFCs application.
Alkaline direct ethanol fuel cells (DEFCs) represent an efficient energy conversion device for sustainable ethanol fuel. In this study, a design with new structural parameters for the anodic flow ...field of the alkaline DEFC was modeled with the aid of computational fluid dynamics and was then actually constructed. Single-cell tests were performed to evaluate the impact of the developed design on fuel cell performance. The results show that fuel cell performance significantly increased when using the improved design in the low-temperature range. The higher the temperature in the cell, the lower the influence of the flow field structure on performance. In addition, the influence of external factors, such as the orientation of the cell, the preheating of the fuel, and the direction of the two fuel flows relative to each other (co-current and counter-current), are shown.
After a one-year delay caused by the COVID-19 pandemic, the 8th Regional Symposium on Electrochemistry of South-East Europe was held jointly with the 9th Kurt Schwabe Symposium from July 11-15, 2022 ...at Graz University of Technology in Austria. This special edition of the jESE contains a collection of articles presented at this meeting. The 5-day event (including Monday’s Satellite Student Symposium) organized by the Association of South-East European Electrochemists (ASEEE) featured 5 plenaries, 15 keynotes, 71 contributed talks and 38 posters and was attended by 152 scientists and researchers from 23 countries.
The utilization of locally available renewable resources is crucial for the creation of a sustainable energy system in the future. Biogas, a product of the anaerobic digestion of biogenic residues, ...exhibits great potential as feedstock to generate hydrogen for fuel cell mobility applications. A 10 kW fixed-bed chemical looping research system, to-date the largest in the world, was operated to prove the applicability of this versatile process for synthetic biogas utilization. In this experimental study, the focus was laid on examining the influence of different operating parameters (biogas composition, steam co-feeding, process temperature) on the attainable hydrogen purity and system efficiency. The generated hydrogen, between 90 to 230 g per cycle, was characterized online by ppm-range gas analysis and exhibited a product gas quality between 99.8% and 99.998%. The difference observed is attributed to carbon deposition if synthetic biogas with an increased share of carbon dioxide was supplied. This study involved the longest uninterrupted period of operation of a lab prototype system for fixed-bed chemical looping with 250 hours of time-on-stream, four months of discontinuous service and 50 consecutive experimental cycles.
Experimental proof of synthetic biogas utilization for high-purity hydrogen generation (99.998%) with a 10 kW fixed-bed chemical looping system.
The anion exchange membrane is one of the core components that play a crucial and inseparable role in alkaline anion exchange membrane fuel cells. Anion exchange membranes (AEMs) were prepared from ...quaternary ammonium poly(vinyl alcohol) (QPVA) by an electrospinning method. QPVA was used both as material for electrospun fiber mats and as filler for the inter-fiber void matrix. The objective of this work is to investigate the influence of the inter-fibers void matrix filler concentration on the properties and performance of eQPVA-x AEMs. FTIR spectra were used to identify the chemical structures of the AEMs. The primary functional groups of PVA and quaternary ammonium-based ion conducting cation were detected. The surface morphology of QPVA nanofiber mats and eQPVA-x AEMs was observed using SEM. Electrospun nanofiber structures of QPVA with an average size of 100.96 nm were observed in SEM pictures. The ion exchange capacity, swelling properties, water uptake, and OH-ions conductivity were determined to evaluate the performance of eQPVA-x AEMs. By incorporating the QPVA matrix of 5 wt.% concentration, the eQPVA-5.0 AEMs attained the highest ion exchange capacity, water uptake, swelling properties, and OH− conductivity of 0.82 mmol g−1, 25.5%, 19.9%, and 2.26 m×s cm−1, respectively. Electrospun QPVA AEMs have the potential to accelerate the development of alkaline anion exchange membrane fuel cells.
In the present work, Ni@Pd core–shell nanoparticles are successfully deposited on multi-walled carbon nanotubes as support and investigated their performance towards formate oxidation reaction. The ...structural features of the catalyst are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. According to the results, the size of the Ni@Pd core–shell nanoparticles is 5–10 nm and the nanoparticles are uniformly deposited on the multi-walled carbon nanotubes. The performance of the synthesized electrocatalysts for the formate oxidation reaction is investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy as well as their comparison with Ni–Pd alloy nanoparticles on multi-walled carbon nanotubes. The results indicated that the Ni@Pd core–shell nanoparticles on multi-walled carbon nanotubes show higher electrocatalytic activity and stability than the Ni–Pd alloy nanoparticles on multi-walled carbon nanotubes against formate electrooxidation reaction. Moreover, the efficiency of synthesized anodic electrocatalysts is evaluated in a direct sodium formate-hydrogen peroxide fuel cell by employing a Pt/carbon as cathode (0.5 mg cm
−2
) and Ni@Pd core–shell nanoparticles on multi-walled carbon nanotubes as anode (1 mg cm
−2
). A maximum power density of 45.56 mW cm
−2
at 25 °C is achieved for this measurement.
Graphical abstract
Polymer electrolyte membrane water electrolysis (PEMWE) is a leading candidate for the development of a sustainable hydrogen infrastructure. The heart of a PEMWE cell is represented by the membrane ...electrode assembly (MEA), which consists of a polymer electrolyte membrane (PEM) with catalyst layers (CLs), flow fields, and bipolar plates (BPPs). The weakest component of the system is the PEM, as it is prone to chemical and mechanical degradation. Membrane chemical degradation is associated with the formation of hydrogen peroxide due to the crossover of product gases (H
and O
). In this paper, membrane failure due to H
crossover was addressed in a membrane-focused accelerated stress test (AST). Asymmetric H
O and gas supply were applied to a test cell in OCV mode at two temperatures (60 °C and 80 °C). Electrochemical characterization at the beginning and at the end of testing revealed a 1.6-fold higher increase in the high-frequency resistance (HFR) at 80 °C. The hydrogen crossover was measured with a micro-GC, and the fluoride emission rate (FER) was monitored during the ASTs. A direct correlation between the FER and H
crossover was identified, and accelerated membrane degradation at higher temperatures was detected.
Herein, we prepared a series of nanocomposite membranes based on chitosan (CS) and three compositionally and structurally different N-doped graphene derivatives. Two-dimensional (2D) and quasi 1D ...N-doped reduced graphene oxides (N-rGO) and nanoribbons (N-rGONRs), as well as 3D porous N-doped graphitic polyenaminone particles (N-pEAO), were synthesized and characterized fully to confirm their graphitic structure, morphology, and nitrogen (pyridinic, pyrrolic, and quaternary or graphitic) group contents. The largest (0.07%) loading of N-doped graphene derivatives impacted the morphology of the CS membrane significantly, reducing the crystallinity, tensile properties, and the KOH uptake, and increasing (by almost 10-fold) the ethanol permeability. Within direct alkaline ethanol test cells, it was found that CS/N rGONRs (0.07 %) membrane (P
. = 3.7 mWcm
) outperformed the pristine CS membrane significantly (P
. = 2.2 mWcm
), suggesting the potential of the newly proposed membranes for application in direct ethanol fuel cells.
PDF
