Novel octopus shaped organic-inorganic composite membranes for PEMFCs

© 2016 Hydrogen Energy Publications LLC.Phosphoric acid doped polybenzimidazoles are among the most interesting proton exchange membrane materials for high temperature proton exchange membrane fuel cell applications. As a major challenge the proton conducting decline due to free phosphoric acid leaching during the long term fuel cell operation is addressed by fixing overmuch phosphoric acid in the polymer matrix. Novel organic-inorganic composite membranes are prepared via in situ synthesis of poly(2,5-benzimidazole) (ABPBI) and OctaAmmonium POSS (AM-POSS) hybrid composites (ABPBI/AM-POSS) following phosphoric acid doping and membrane casting procedures. Compared with the pristine ABPBI membrane, the introduction of AM-POSS into ABPBI polymer membrane caused water and phosphoric acid absorbilities increasing dramatically, resulting in the significant increase of proton conductivities at whether hydrous or anhydrous condition. ABPBI/3AM composite membranes with phosphoric acid uptake above 250% showed best proton conductivities from room temperature to 160 °C, indicating these composite membranes could be excellent candidates as a polymer electrolyte membrane for low and intermediate temperature applications

Degradation of (La_0.6Sr_0.4)_0.95(Co_0.2Fe_0.8)O_3−δ Solid Oxide Fuel Cell Cathodes at the Nanometer Scale and below

The degradation of intermediate temperature solid oxide fuel cell (ITSOFC) cathodes has been identified as a major issue limiting the development of ITSOFCs as high efficiency energy conversion devices. In this work, the effect of Cr poisoning on (La_0.6Sr_0.4)_0.95(Co_0.2Fe_0.8)­O_3‑δ (LSCF6428), a particularly promising ITSOFC cathode material, was investigated on symmetrical cells using electrochemical impedance spectroscopy and multiscale structural/chemical analysis by advanced electron and ion microscopy. The systematic combination of bulk and high-resolution analysis on the same cells allows, for the first time, direct correlation of Cr induced performance degradation with subtle and localized structural/chemical changes of the cathode down to the atomic scale. Up to 2 orders of magnitude reduction in conductivity, oxygen surface exchange rate, and diffusivity were observed in Cr poisoned LSCF6428 samples. These effects are associated with the formation of nanometer size SrCrO₄; grain boundary segregation of Cr; enhanced B-site element exsolution (both Fe and Co); and reduction in the Fe valence, the latter two being related to Cr substitution in LSCF. The finding that significant degradation of the cathode happens before obvious microscale change points to new critical SOFC degradation mechanisms effective at the nanometer scale and below

Self-Assembling Peptide Nanofiber Scaffolds Enhance Dopaminergic Differentiation of Mouse Pluripotent Stem Cells in 3-Dimensional Culture

<div><p>Dopaminergic differentiation of embryonic stem cells (ESCs) gains more and more attention worldwide owing to its potential use for neurorestorative therapy for the treatment of Parkinson’s disease. The conventional 2D cell culture on petri dishes with various animal derived substrata such as collagen gels, laminin, and Matrigel is widely used to induce dopaminergic differentiation and it may limit the efficiency in the generation of dopaminergic neurons from ESCs and prevent their application for human therapies. Here, we reported that a self-assembling peptide made from natural amino acids has a property to generate a true 3D environment for dopaminergic differentiation. Mouse ESCs (R1) and mouse iPSCs (TTF-1) embedded in RADA16-I peptide-derived nanofiber scaffolds led to a marked increase in dopaminergic differentiation compared to the laminin-coated 2D culture or Matrigel-encapsulated 3D culture. These differentiated neurons expressed specific dopaminergic markers and produced appropriate patterns of action potential firing. Consistent with the increase in the number of dopaminergic neurons differentiated from R1 or TTF-1 in the self-assembling peptide nanofiber scaffold (SAPNS), both the expression levels of genes that involve in dopaminergic differentiation and maturation and the dopamine release in SAPNS culture were significantly elevated. The results of the study suggest that SAPNS provides a promising 3D culture system for dopaminergic differentiation.</p> </div

Derivation of neural progenitors from R1 and TTF-1 cells.

<p>(A) and (D) Phase contrast image shows that R1 and TTF-1 cells grew as colonies on mitomycin-treated MEF feeder cells. (B) and (E) Phase contrast image shows neural rosettes derived from R1 and TTF-1 cells. (C) and (F) Immunostaining reveals that predominantly cells in rosettes R1 and TTF-1 cells were Nestin positive. Scale bar: 200 µm in A and D; 150 µm in B, C, E, and F.</p

Dopaminergic differentiation of R1 cells was significantly improved in SAPNS-3D culture.

<p>(A) Immunocytochemistry for TH and Tuj1 revealed the dopaminergic differentiation of R1 in Laminin-2D culture. (B) Immunocytochemistry for TH and Tuj1 revealed the dopaminergic differentiation of R1 in Matrigel-3D culture. (C) Immunocytochemistry for TH and Tuj1 revealed the dopaminergic differentiation of R1 in SAPNS-3D culture. (D) The percentage of TH-positive cells of total Tuj1-positive cells was 41.5% ± 3.4% in SAPNS-3D culture, which was significantly higher than 8.3% ± 1.4% in the laminin-2D culture and 7.9% ± 1.6% in Matrigel-3D culture. *P<0.001. Scale bar: 150 µm.</p

Relative mRNA expression levels of dopaminergic differentiation markers (<i>Lmx1a</i>, <i>Foxa2</i>, En1, <i>Aadc</i>, <i>Nurr1</i>, Th, <i>Vmat2</i>, and <i>Dat</i>) in laminin-2D culture, Matrigel-3D culture and SAPNS-3D culture respectively.

<p>Quantitative real-time RT-PCR demonstrated that a 4-fold increase for <i>Lmx1a</i> (A), 5-fold increase for <i>Nurr1</i> (E), <i>Vmat2</i> (G), and <i>Dat</i> (H), 6-fold increase for En1 (C) and <i>Aadc</i> (D), and 7-fold increase for <i>Foxa2</i> (B) and Th (F) were found in both R1 and TTF-1 differentiation when cultured in SAPNS as compared to their expressions in Matrigel or on laminin.</p

The majority of TH positive neurons co-expressed specific midbrain dopaminergic neuron markers.

<p>(A-C) Characterization of R1-derived TH positive neurons in SAPNS. (A) Double immunostaining showed that R1-derived TH positive neurons were co-labeled with Nurrl; (B) Double immunostaining showed that R1-derived TH positive neurons were co-labeled with Dat; (C) The majority of R1-derived TH positive neurons co-expressed Nurr1 or Dat. (D-F) Characterization of TTF-1-derived TH positive neurons in SAPNS. (D) Double immunostaining showed that TTF-1-derived TH positive neurons were co-labeled with Nurrl; (E) Double immunostaining showed that TTF-1-derived TH positive neurons were co-labeled with Dat; (F) The majority of TTF-1-derived TH positive neurons co-expressed Nurr1 or Dat. Scale bar: 100 µm.</p

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

The solar-assisted oxidation of water is an essential half reaction for achieving a complete cycle of water splitting. The search of efficient photoanodes that can absorb light in the visible range is of paramount importance to enable cost-effective solar energy-conversion systems. Here, we demonstrate that atomically thin layers of MoS₂ and WS₂ can oxidize water to O₂ under incident light. Thin films of solution-processed MoS₂ and WS₂ nanosheets display <i>n</i>-type positive photocurrent densities of 0.45 mA cm^–2 and O₂ evolution under simulated solar irradiation. WS₂ is significantly more efficient than MoS₂; however, bulk heterojunctions (B-HJs) of MoS₂ and WS₂ nanosheets results in a 10-fold increase in incident-photon-to-current-efficiency, compared to the individual constituents. This proves that charge carrier lifetime is tailorable in atomically thin crystals by creating heterojunctions of different compositions and architectures. Our results suggest that the MoS₂ and WS₂ nanosheets and their B-HJ blend are interesting photocatalytic systems for water oxidation, which can be coupled with different reduction processes for solar-fuel production

Toward High CO Selectivity and Oxidation Resistance Solid Oxide Electrolysis Cell with High-Entropy Alloy

Ni-based cermet materials still persist as pronounced challenges for electrocatalysts in solid oxide electrolysis cells (SOECs), due to their insufficient CO2 catalytic efficiency and inferior resistance to oxidation. In this paper, a (Fe,Co,Ni,Cu,Mo) quinary high-entropy alloy is explored as an alternative cathode material, offering enhanced performance in the co-electrolysis of H2O and CO2 for renewable syngas production. In comparison to traditional nickel-based cathodes, an assembled SOEC employing the as-designed quinary high-entropy alloy exhibits a remarkable increase in CO2 conversion capacity and significantly enhanced oxidation resistance. In addition, the electrolysis current density increases by 18%, and a stability test for more than 110 h reveals no degradation. Moreover, the stability can be maintained for up to 40 h even without any protective gas. Morphological and spectroscopic analyses, coupled with density functional theory (DFT) calculations, elucidate that the high-entropy effect facilitates surface electron redistribution, which in turn contributes to the measurable activity by reducing the energy barrier of CO2 activation. Notably, the superior resistance to oxidation primarily originates from the in situ-formed spinel phase under oxidation conditions. This study demonstrates the satisfying performance of high-entropy alloys as cathode materials in SOEC, validating their high application potential in this field