Preparation of hollow PtCu nanoparticles as high-performance electrocatalysts for oxygen reduction reaction in the absence of a surfactant

Hollow PtCu nanoparticles of about 6.9 nm supported on Vulcan XC-72 were synthesized by a facile method in the absence of a surfactant. The hollow structure was evident in TEM, HRTEM and HAADF-STEM images. The lattice contraction of specific PtCu nanoparticles was directly observed with the aid of HRTEM; furthermore, the lattice compression of the whole PtCu sample was examined by XRD. As surface sensitive measurements, XPS and CV demonstrated that the PtCu nanoparticle was covered by a Pt skin with subsurface PtCu alloy. Based on a half-cell test, the PtCu/C electrocatalysts displayed impressive ORR performance compared with the state-of-the-art Pt/C (JM). The enhanced ORR performance was attributed to the reduced adsorption strength of OHads on the surface of the PtCu nanostructures, resulting from the hollow-induced lattice compression and subsurface alloy effect. In addition, the hollow PtCu nanostructure was confirmed to be stable by two facts: (i) the hollow structure was still visible and the particle size change of PtCu was not apparent and (ii) the area-specific activity and mass activity of PtCu didn't decrease greatly after an accelerated degradation test

Functionalization of polybenzimidazole-crosslinked poly(vinylbenzyl chloride) with two cyclic quaternary ammonium cations for anion exchange membranes

The anion exchange membranes (AEMs) with both high ionic conductivity and good stability is always the research focus role for the long-term use of AEM fuel cells. A series of the mechanically and chemically stable PVBC/PBI crosslinked membranes, functionalized with N1-butyl substituted BDABCO groups, were designed, prepared and characterized. With the crosslinking by polybenzimidazole (PBI), the membranes showed good flexibility, strength and low swelling ratio (less than 18%). N1-butyl substituted doubly-charged BDABCO was introduced in the AEMs during the crosslinking reaction instead of the traditional dipping method, benefiting from the improvement compatibility between polymers and BDABCO groups. Attributing to the well-developed phase separation between hydrophilic domains and hydrophobic domains, the family of synthesized AEMs exhibited the higher conductivities than that of DABCO based membranes, which was proved by TEM and SAXS. The M-BDABCO-OH-1: 3 with high BDABCO content displayed the highest ionic conductivity of 29.3 and 91.4 mS cm(-1) at 20 and 80 degrees C, respectively. The results of alkaline stability showed that the membranes had the superior chemical stability after immersing in a 1 mol L-1 KOH at 60 degrees C solution for more than 550 h. Furthermore, the peak power density of an H-2/O-2 single fuel cell using the optimized M-BDABCO-OHAEMFCs-1: 3 was up to 340 mW cm(-2) at 0.492 V with the EIS consisting of membrane resistance less than 0.1 Omega cm(2) which was much smaller than the other AEMs. Overall, the developed membranes demonstrated the superior performance and would be a promising candidate material for AEMFCs

The Main Anthocyanin Monomer from <i>Lycium ruthenicum</i> Murray Fruit Mediates Obesity via Modulating the Gut Microbiota and Improving the Intestinal Barrier

Anthocyanins have been shown to exert certain antiobesity properties, but the specific relationship between anthocyanin-induced beneficial effects and the gut microbiota remains unclear. Petunidin-3-O-[rhamnopyranosyl-(trans-p-coumaroyl)]-5-O-(β-D-glucopyranoside) (P3G) is the main anthocyanin monomer from the fruit of Lycium ruthenicum Murray. Therefore, in this study, we investigated the antiobesity and remodeling effects of P3G on gut microbiota through a high-fat diet (HFD)-induced obesity mouse model and a fecal microbiota transplantation experiment. P3G was found to reduce body weight gain, fat accumulation, and liver steatosis in HFD-induced obese mice. Moreover, supplementation with P3G alleviated the HFD-induced imbalance in gut microbiota composition, and transferring the P3G-regulated gut microbiota to recipient mice provided comparable protection against obesity. This is the first time evidence is provided that P3G has an antiobesity effect by changing the intestinal microbiota. Our present data highlight a link between P3G intervention and enhancement in gut barrier integrity. This may be a promising option for obesity prevention

Zeaxanthin Dipalmitate-Enriched Emulsion Stabilized with Whey Protein Isolate-Gum Arabic Maillard Conjugate Improves Gut Microbiota and Inflammation of Colitis Mice

In the present study, protein-polysaccharide Maillard conjugates were used as novel emulsifiers and bioactive carriers. Effects and potential mechanisms of zeaxanthin dipalmitate (ZD)-enriched emulsion stabilized with whey protein isolate (WPI)-gum Arabic (GA) conjugate (WPI-GA-ZD) and ZD-free emulsion (WPI-GA) on gut microbiota and inflammation were investigated using a model of dextran sulfate sodium (DSS)-induced colitis in mice. As a result, supplementation with WPI-GA and WPI-GA-ZD improved the serum physiological and biochemical indicators, decreased the expression of pro-inflammatory cytokines and related mRNA, as well as increased the tight junction proteins to a certain extent. 16S rDNA sequencing analyses showed that supplementation with WPI-GA and WPI-GA-ZD presented differential modulation of gut microbiota and played regulatory roles in different metabolic pathways to promote health. Compared with WPI-GA, the relative abundances of Akkermansia, Lactobacillus and Clostridium_IV genera were enriched by the intervention of WPI-GA-ZD. Overall, the designed carotenoid-enriched emulsion stabilized with protein-polysaccharide conjugates showed potential roles in promoting health

One-pot synthesis of Ir@Pt nanodendrites as highly active bifunctional electrocatalysts for oxygen reduction and oxygen evolution in acidic medium

Nanodendritic Ir@Pt core-shell bifunctional electrocatalysts were synthesized by a one-pot synthesis method for the first time. Besides good dispersion and uniform composition distribution, Ir@Pt bifunctional electrocatalysts have exhibited outstanding catalytic activity for both oxygen reduction and oxygen evolution reactions in comparison with the mixture of commercial Ir and Pt blacks. Keywords: Unitized regenerative fuel cell, Bifunctional electrocatalyst, Nanodendrite, Core-shell, Iridium, Platinu

Fast sulfurization of nickel foam-supported nickel-cobalt carbonate hydroxide nanowire array at room temperature for hydrogen evolution electrocatalysis

International audienc

Preparation and characterization of partial-cocrystallized catalyst-coated membrane for solid polymer electrolyte water electrolysis

A novel catalyst-coated membrane (CCM) for solid polymer electrolyte water electrolysis was fabricated by together crystallizing partial-crystallized Nafion membrane and catalyst layers. The properties and performance of the partial-cocrystallized CCM (PCCCM) were evaluated and analyzed by destructive soaking test, scanning electron microscope, mercury intrusion and single cell test. The results revealed that the optimum annealing temperature and time for fabricating partial-crystallized Nafion membrane and PCCCM was 100 degrees C for 4 h and 120 degrees C for 4 h, respectively. The PCCCM not only possessed much stronger cohesion between membrane and catalyst layers, but also had higher porosity than conventional CCM. The electrolysis Voltage of the SPE water electrolyser with the new CCM was as low as 1.748 V at 2000 mA cm(-2) under 80 degrees C and atmospheric pressure: Moreover, there was no obvious increase of electrolysis voltage during stability test conducted under 2000 mA cm(-2) for about 180 h. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

In-Situ Transformed Ni, S-Codoped CoO from Amorphous Co–Ni Sulfide as an Efficient Electrocatalyst for Hydrogen Evolution in Alkaline Media

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A cocrystallized catalyst-coated membrane with high performance for solid polymer electrolyte water electrolysis

A cocrystallized catalyst-coated membrane (CCM) is prepared by together heating amorphous Nafion membrane and catalyst layers at 120 degrees C to develop the membrane electrode assembly for solid polymer electrolyte (SPE) water electrolysis. The cocrystallization treatment effectively reinforces the bonding between membrane and catalyst layers, and increases the hydrophobicity of the catalyst layers. The SPE water electrolyser with the cocrystallized CCM decreased cell voltage by 0.09 V at 2000 mA cm(-2) at 80 degrees C and improved the stability in comparison with the conventional CCM. (C) 2013 Elsevier B.V. All rights reserved

The electric double layer structure modulates poly-dT 25 conformation and adsorption kinetics at the cationic lipid bilayer interface

International audienc