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This study proposes a hydrophobic and hydrophilic aliphatic diblock copolymer wherein the hydrophobic block contains glycidyl methacrylate (GMA) units that are distanced by poly(acrylonitrile) (PAN) segments to fabricate a proton exchange membrane (PEM). This diblock copolymer also known as ionomer due to the hydrophilic block comprising 3-sulfopropyl methacrylate potassium salt (SPM) block. The diblock copolymer was synthesized in the one-pot atom transfer radical polymerization (ATRP) synthesis. Subsequently, the membrane was fabricated by means of solution casting in which an organic diamine, e.g., ethylene diamine (EDA), was introduced to crosslink the diblock copolymer chains via the addition of amine to the epoxide group of GMA. As a result, the PEM attained possesses dual continuous phases, in which the hydrophobic domains are either agglomerated or bridged by the EDA-derived crosslinks, whereas the hydrophilic domains constitute the primary proton conducting channels. The in-situ crosslinking hydrophobic block by using a hydrophilic cross-linker represents the merit aspect since it leads to both improved proton conductivity and dimensional stability in alcohol fuel. To characterize the above properties, Nafion® 117 and random copolymer of P(AN-co-GMA-co-SPM) were used as control samples. The PEM with the optimized composition demonstrates slightly better fuel cell performance than Nafion 117. Lastly, this diblock ionomer is nonfluorinated and hence favors lowering down both material and environmental costs.

While there are well-established personal benefits to being a mentor, such as increased life satisfaction and job performance (Ramaswami & Dreher, 2007), how mentors grow and develop requires exploration. We meet this need by presenting six key themes from two recent research studies related to the experiences that mentors perceived as contributing to their development. The growth of two leadership theories in particular were explored: generativity and Psychological Capital. Six themes emerged: (a) curricular training, (b) exposure to leadership outcomes, (c) being mentored by peers, (d) experiences with mentee, (e) reflection, and (f) observing a ripple effect. These themes offer insights on how curricular and co-curricular experiences might maximize leadership development of students and ground leadership interventions, such as mentoring, in theory and research.

We report 3D coherent diffractive imaging (CDI) of Au/Pd core-shell nanoparticles with 6.1 nm spatial resolution with elemental specificity. We measured single-shot diffraction patterns of the nanoparticles using intense x-ray free electron laser pulses. By exploiting the curvature of the Ewald sphere and the symmetry of the nanoparticle, we reconstructed the 3D electron density of 34 core-shell structures from these diffraction patterns. To extract 3D structural information beyond the diffraction signal, we implemented a super-resolution technique by taking advantage of CDI's quantitative reconstruction capabilities. We used high-resolution model fitting to determine the Au core size and the Pd shell thickness to be 65.0 ± 1.0 nm and 4.0 ± 0.5 nm, respectively. We also identified the 3D elemental distribution inside the nanoparticles with an accuracy of 3%. To further examine the model fitting procedure, we simulated noisy diffraction patterns from a Au/Pd core-shell model and a solid Au model and confirmed the validity of the method. We anticipate this super-resolution CDI method can be generally used for quantitative 3D imaging of symmetrical nanostructures with elemental specificity.

High sulfur loading and long cycle life are the design targets of commercializable lithium–sulfur (Li–S) batteries. The sulfur electrochemical reactions from Li2S4 to Li2S, which account for 75% of the battery's theoretical capacity, involve liquid‐to‐solid and solid‐to‐solid phase changes in all Li–S battery electrolytes in use today. These are kinetically hindered processes that are exacerbated by a high sulfur loading. In this study, it is observed that an in situ grown bimetallic phosphide/black phosphorus (NiCoP/BP) heterostructure can effectively catalyze the Li2S4 to Li2S reactions to increase the sulfur utilization at high sulfur loadings. The NiCoP/BP heterostructure is a good polysulfide adsorber, and the electric field prevailing at the Mott−Schottky junction of the heterostructure can facilitate charge transfer in the Li2S4 to Li2S2 liquid‐to‐solid reaction and Li+ diffusion in the Li2S2 to Li2S solid‐state reaction. Consequently, a sulfur cathode with the NiCoP/BP catalyst can deliver a specific capacity of 830 mAh g−1 at the sulfur loading of 6 mg cm−2 for 500 cycles at the 0.5 C rate. High sulfur utilization is also possible at a higher sulfur loading of 8 mg cm−2 for 440 cycles at the 1 C rate. [ABSTRACT FROM AUTHOR]

A layered SnS2-reduced graphene oxide (SnS2-RGO) composite is prepared by a facile hydrothermal route and evaluated as an anode material for sodium-ion batteries (NIBs). The measured electrochemical properties are a high charge specific capacity (630 mAh g-1 at 0.2 A g-1) coupled to a good rate performance (544 mAh g-1 at 2 A g-1) and long cycle-life (500 mAh g-1 at 1 A g -1 for 400 cycles). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.