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The development of low-cost, highly active and stable electrocatalysts for oxygen evolution reaction (OER) is desirable and challenging. In this work, we report nickel foam (NF) supported low-crystalline NiCoFe nanosheet...

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With the proliferation of web services offering similar functionality, how to choose the optimal service composition that meet consumer demands based on Qos-aware has become increasingly difficult. In this paper, we study the web service composition problem in a sequential composition model. In this work, we propose an optimized artificial bee colony algorithm (OABC) to make it more suitable for the problem. On one hand, this algorithm uses the group initialization strategy based on opposition learning to enhance the diversity of the initial population. On the other hand, in order to improve the exploration and exploitation ability of the algorithm, we dynamically adjust the neighborhood search range during the hired bee phase and introduce a global optimal bee behavior in the scout bee phase. Our experimental results demonstrate the good performance of the solutions obtained by OABC algorithm in fitness and execution time when compared with other existing algorithms. Index Terms-Web service composition, Qos-aware, artificial bee colony (ABC), optimized artificial bee colony (OABC).

The efficient hydrogenation of biomass-derived levulinic acid (LA) to value-added γ-valerolactone (GVL) based on nonprecious metal catalysts under mild conditions is crucial challenge because of the intrinsic inactivity and instability of these catalysts. Herein, a series of highly active and stable carbon-encapsulated Co/ZnO@C-X (where X = 0.1, 0.3, 0.5, the molar ratios of Zn/(Co+Zn)) heterojunction catalysts were obtained by in situ pyrolysis of bimetal CoZn MOF-74. The optimal Co/ZnO@C-0.3 catalyst could achieve 100% conversion of LA and 98.35% selectivity to GVL under mild conditions (100 °C, 5 bar, 3 h), which outperformed most of the state-of-the-art catalysts reported so far. Detailed characterizations, experimental investigations, and theoretical calculations revealed that the interfacial interaction between Co and ZnO nanoparticles (NPs) could promote the dispersibility and air stability of the active Co0 for the activation of H2. Moreover, the strong Co–ZnO interaction also enhanced the Lewis acidity of the Co/ZnO interface, contributing to the adsorption of LA and the esterification of intermediates. The synergy between the hydrogenation sites and the Lewis acid sites at the Co/ZnO interface enabled the conversion of LA to GVL with high efficiency. In addition, benefiting from the Co–ZnO interfacial interaction as well as the unique carbon-encapsulated structure of the heterojunction catalyst, the recyclability was also greatly improved and the yield of GVL was nearly unchanged even after six cycles.