Robust poly(p-phenylene oxide) anion exchange membranes reinforced with pore-filling technique for water electrolysis

\ua9 2024 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals LLC. Mechanical robustness and durability are crucial for anion exchange membranes to guarantee the longevity and consistent performance of AEM water electrolysis (AEMWE) systems. In this study, a composite membrane based on the quaternized poly(p-phenylene oxide) (QPPO)/polytetrafluoroethylene (PTFE) was developed. This membrane was fabricated by enhancing the QPPO-based AEM through a pore-filling technique within a porous PTFE structure. The tensile strength of the composite membrane was increased significantly from 16.5 to 31 MPa. The conductivity of the composite membrane was 6.25 mScm−1 lower than 30 mScm−1 of the QPPO-based membrane at 20\ub0C, resulting from the low volume fraction of QPPO in the composite membrane. At 40% RH, the net change mass of the composite membrane is 1.59%, much lower than that of QPPO-based membrane (10.98%) at 40\ub0C. The composite membrane demonstrated a significantly increased lifetime in the working electrolyzer (>200 h) compared with an otherwise identical electrolyzer assembled with a QPPO-based membrane (50 h)

Degradation of QPPO-based anion polymer electrolyte membrane at neutral pH

\ua9 2023 The Royal Society of ChemistryThe chemical stability of anion polymer electrolyte membranes (AEMs) determines the durability of an AEM water electrolyzer (AEMWE). The alkaline stability of AEMs has been widely investigated in the literature. However, the degradation of AEM at neutral pH closer to the practical AEMWE operating condition is neglected, and the degradation mechanism remains unclear. This paper investigated the stability of quaternized poly(p-phenylene oxide) (QPPO)-based AEMs under different conditions, including Fenton solution, H2O2 solution and DI water. The pristine PPO and chloromethylated PPO (ClPPO) showed good chemical stability in the Fenton solution, and only limited weight loss was observed, 2.8% and 1.6%, respectively. QPPO suffered a high mass loss (29%). Besides, QPPO with higher IEC showed a higher mass loss. QPPO-1 (1.7 mmol g−1) lost nearly twice as much mass as QPPO-2 (1.3 mmol g−1). A strong correlation between the degradation rate of IEC and H2O2 concentration was obtained, which implied that the reaction order is above 1. A long-term oxidative stability test at pH neutral condition was also conducted by immersing the membrane in DI at 60 \ub0C water for 10 months. The membrane breaks into pieces after the degradation test. The possible degradation mechanism is that oxygen or OH˙ radicals attack the methyl group on the rearranged ylide, forming aldehyde or carboxyl attached to the CH2 group

Three dimensional model of a high temperature PEMFC using PBI doped phosphoric acid membranes. Study of the flow field effect on performance

A three-dimensional isothermal model of a high temperature polymer membrane fuel cell equipped with polybenzimidazole (PBI) membrane is described. All major transport phenomena were taken into account except the species cross-over thought the membrane. The cathode catalyst layer was treated as spherical catalyst agglomerates with porous inter-agglomerate spaces. The inter-agglomerate spaces were filled with a mixture of electrolyte (hot phosphoric acid) and polytetrafluoroethylene (PTFE). This approach proved to be an essential requirement for accurate simulation. In this particular paper the influence of different flow field designs and dimensions on performance was intensely study. Traditional configurations were tested (straight, serpentine, pin-in and interdigitated), and a new designs were proposed. With these new designs we tried to maximize performance by providing homogeneous reactants distribution over the active area keeping low pressure drop and relatively high velocity. The dimension and position of the inlet and outlet manifolds were also analysed. From the obtained results was observed a massive influence of the manifolds position and dimension on performance. This fact leaded to an optimization of the manifolds which can give important guidelines for future bipolar plates production

Review of next generation hydrogen production from offshore wind using water electrolysis

\ua9 2023 The Author(s)Hydrogen produced using renewable energy from offshore wind provides a versatile method of energy storage and power-to-gas concepts. However, few dedicated floating offshore electrolyser facilities currently exist and therefore conditions of the offshore environment on hydrogen production cost and efficiency remain uncertain. Therefore, this review focuses on the conversion of electrical energy to hydrogen, using water electrolysis located in offshore areas. The challenges associated with the remote locations, fluctuating power and harsh conditions are highlighted and recommendations for future electrolysis system designs are suggested. The latest research in polymer electrolyte membrane, alkaline and membraneless electrolysis are evaluated in order to understand their capital costs, efficiency and current research status for achieving scaled manufacturing to the GW scale required in the next three decades. Operating fundamentals that govern the performance of each device are investigated and future recommendations of research specifically for the integration of water electrolysers with offshore wind turbines is presented

Boosting the oxygen evolution activity in non-stoichiometric praseodymium ferrite-based perovskites by A site substitution for alkaline electrolyser anodes

Sustainable fossil fuel free systems are crucial for tackling climate change in the global energy market, and the identification and understanding of catalysts needed to build these systems plays a vital role in their development. ABO3−δ perovskite oxides have been observed to be potential replacement materials for the high-performing, but low ionic conducting and economically unfavourable Pt and IrO2 water splitting catalysts. In this work increased addition of Sr2+ aliovalent dopant ions into the crystal lattice of Pr1−xSrxFeO3−δ perovskites via A site substitution was seen to drastically improve the electrocatalytic activity of the oxygen evolution reaction (OER) in alkaline environments. The undoped PrFeO3−δ catalyst was not catalytically active up to 1.70 V against the reversible hydrogen electrode (RHE), whilst an onset potential of 1.62 V was observed for x = 0.5. Increased strontium content in Pr1−xSrxFeO3−δ was found to cause a reduction in the lattice parameters and crystal volume whilst retaining the orthorhombic Pbnm space group throughout all dopant levels, analysed using the Rietveld method. However, it was noted that the orthorhombic distortion was reduced as more Sr2+ replaced Pr3+. The mechanism for the increased electrocatalytic activity with increased strontium is due to the increasing concentration of oxygen vacancy (δ), leading to increased catalyst site availability, and the increased average oxidation state of Fe cations, consistent with the iodometric titration results. This results in shifting the average d shell eg electron filling further towards unity. X-ray photoelectron spectrum of the O 1s core level also shows the presence of lattice oxide and surface hydroxide/carbonate. This work shows promise in that using the more abundant and more economically friendly material of strontium allows for improved OER catalytic activity in otherwise inactive perovskite catalyst oxides

DNA copy number changes define spatial patterns of heterogeneity in colorectal cancer

Genetic heterogeneity between and within tumours is a major factor determining cancer progression and therapy response. Here we examined DNA sequence and DNA copy-number heterogeneity in colorectal cancer (CRC) by targeted high-depth sequencing of 100 most frequently altered genes. In 97 samples, with primary tumours and matched metastases from 27 patients, we observe inter-tumour concordance for coding mutations; in contrast, gene copy numbers are highly discordant between primary tumours and metastases as validated by fluorescent in situ hybridization. To further investigate intra-tumour heterogeneity, we dissected a single tumour into 68 spatially defined samples and sequenced them separately. We identify evenly distributed coding mutations in APC and TP53 in all tumour areas, yet highly variable gene copy numbers in numerous genes. 3D morpho-molecular reconstruction reveals two clusters with divergent copy number aberrations along the proximal–distal axis indicating that DNA copy number variations are a major source of tumour heterogeneity in CRC

An efficient cathode electrocatalyst for anion exchange membrane water electrolyzer

\ua9 2024 The AuthorsA high performance and durable electrocatalyst for the cathodic hydrogen evolution reaction (HER) in anion exchange membrane (AEM) water electrolyzers is crucial for the emerging hydrogen economy. Herein, we synthesized Pt–C core-shell nanoparticles (core: Pt nanoparticles, shell: N-containing carbon) were uniformly coated on hierarchical MoS2/GNF using pyrolysis of h-MoS2/GNF with a Pt-aniline complex. The synthesized Pt–C core-shell@h-MoS2/GNF (with 11.3 % Pt loading) showed HER activity with a lower overpotential of 30 mV at 10 mA cm−2 as compared to the benchmark catalyst 20 % Pt–C (41 mV at 10 mA cm−2) with improved durability over 94 h at 10 mA cm−2. Furthermore, we investigated the structural stability and hydrogen adsorption energy for Pt13 cluster, C90 molecule, h-MoS2 sheet, Pt13–C90 core-shell, and Pt13–C90 core-shell deposited h-MoS2 sheets using density functional theory (DFT) simulations. We investigated the Pt–C core-shell@h-MoS2/GNF catalyst active sites during HER performance using in-situ Raman analysis as well as DFT. We fabricated AEM water electrolyzers with cathode catalysts of Pt–C core-shell@h-MoS2/GNF and evaluated device performance with 0.1 and 1.0 M KOH at 20 and 60 \ub0C. Our work provides a new pathway to design core-shell electrocatalysts for use in AEM water electrolyzers to generate hydrogen

Categorical Dimensions of Human Odor Descriptor Space Revealed by Non-Negative Matrix Factorization

In contrast to most other sensory modalities, the basic perceptual dimensions of olfaction remain unclear. Here, we use non-negative matrix factorization (NMF) – a dimensionality reduction technique – to uncover structure in a panel of odor profiles, with each odor defined as a point in multi-dimensional descriptor space. The properties of NMF are favorable for the analysis of such lexical and perceptual data, and lead to a high-dimensional account of odor space. We further provide evidence that odor dimensions apply categorically. That is, odor space is not occupied homogenously, but rather in a discrete and intrinsically clustered manner. We discuss the potential implications of these results for the neural coding of odors, as well as for developing classifiers on larger datasets that may be useful for predicting perceptual qualities from chemical structures

Hierarchical urchin-like CuxCo3−xO4 spinels as oxygen evolution reaction catalysts in alkaline anion exchange membrane water electrolyzers

In this work, powdered hierarchical CuxCo3−xO4 catalysts were used as catalysts for the oxygen evolution reaction (OER) in an alkaline anion exchange membrane water electrolyzer (AAEMWE). The effect of increasing Cu concentration (x = 0, 0.25, 0.5, 0.75, and 1) on the OER catalysis performance of the spinel Co3O4 was studied. In general, Cu-doped Co3O4 samples performed better than the undoped spinel catalyst. The sample synthesized with Cu-doping at x = 0.75 (CCO-0.75) performed the best among the catalysts tested with an overpotential of 385 mV at 10 mA cm−2 in 1 M KOH, which is 24% lower than that recorded for the undoped Co3O4 sample. An AAEMWE was assembled using CCO-0.75 on Ti gas diffusion layer (GDL), and Pt/C on carbon GDL as the anode, and cathode, respectively. The CCO-0.75||Pt/C cell required only 1.65 V to reach 100 mA cm−2 at 60 ℃ in 1 M KOH