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Highly stable dioxin-linked metallophthalocyanine covalent organic frameworks

Chinese Chemical Letters 2021年第12期32卷 3799-3802页

作者： Zepeng Lei Francisco W.S.Lucas enrique canales moya Shaofeng Huang Yicheng Rong Aaron Wesche Patrick Li Lauren Bodkin Yinghua Jin Adam Holewinski Wei Zhang Department of Chemistry University of Colorado BoulderBoulderCO 80309United States Renewable and Sustainable Energy Institute and Department of Chemical and Biological EngineeringUniversity of Colorado BoulderBoulderCO 80309United States

We report a series of highly stable metallophthalocyanine-based covalent organic frameworks(MPc-dxCOFs) linked by robust 1,4-dioxin bonds constructed through nucleophilic aromatic substitution(SNAr)reaction. The chemical structures and crystallinity of the COFs largely remain unchanged even after treating with boiling water(90°C), concentrated acids(12 mol/L HCl) or bases(12 mol/L Na OH), oxidizing(30% H_(2)O_(2)) or reducing agents(1 mol/L NaBH;) for three days due to their stable M-Pc building blocks and resilient dioxin linkers. With metallated phthalocyanine active sites regularly arranged in the stable framework structures, MPc-dx-COFs can be directly used as efficient electrocatalysts for the oxygen reduction reaction(ORR) without pyrolysis treatment that has commonly been used in previous studies.

关键词： Covalent organic framework Metallophthalocyanine Nucleophilic aromatic substitution Dioxin linkage Electrocatalysis Oxygen reduction reaction

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Physical activation of graphene: An effective, simple and clean procedure for obtaining microporous graphene for high-performance Li/S batteries

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Nano Research 2019年第4期12卷 759-766页

作者： Almudena Benitez Alvaro Caballero Julian Morales Jusef Hassoun enrique Rodriguez-Castellon Jesus canales-Vazquez Dpto. Quimica Inorganica e Ingenieria Qutmica Instituto de Quimica Fina y Nanoquimica Universidad de Cordoba 14071 Cordoba Spain Departm ent of Chemical and Pharmaceutical Sciences University of Ferrara Via Fossato di Mortara 17 44121 Ferrara Italy Dpto. de Quimica Inorganica Cristalografia y Mineralogia Facultad de Ciencias Universidad de Malaga 29071 Malaga Spain Instituto de Energias Renovables Universidad de Castilla-La Mancha Paseo de La Investigacion 1 Albacete 02071 Spain

Graphe ne nano sheets are a promising scaffold to accommodate S for achievi ng high performa nee Li/S battery. Nano sheet activation is used as a viable strategy to induce a micropore system and further improve the battery performance. Accordingly, chemical activation methods dominate despite the need of multiple stages, which slow down the process in addition to making them tiresome. Here, a three-dimensional (3D) N-doped graphene specimen was physically activated with CO2, a clean and single step process, and used for the preparation of a sulfur composite (A-3DNG/S). The A-3DNG/S composite exhibited outstanding electrochemical properties such as an excellent rate capability (1,000 mAh·g^-1 at 2C), high reversible capacity and cycling stability (average capacity ~ 800 mAh·g^-1 at 1C after 200 cycles), values which exceed those measured in chemically activated graphene. Therefore, these results support the use of physical activation as a simple and efficient alternative to improve the performance of carbons as an S host for high-performance Li-S batteries.

关键词： physical activation 3D-graphene solvothermal microwave synthesis Li-S battery

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Highly graphitized carbon nanosheets with embedded Ni nanocrystals as anode for Li-ion batteries

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Nano Research 2020年第1期13卷 86-94页

作者： Francisco Javier Soler-Piña Celia Hernández-Rentero Alvaro Caballero Julián Morales enrique Rodríguez-Castellón Jesús canales-Vázquez Dpto.Química Inorgánica e Ingeniería Química Instituto de Química Fina y NanoquímicaUniversidad de Córdoba14071CórdobaSpain Dpto.Química Inorgánica Cristalografía y MineralogíaFacultad de CienciasUniversidad de Málaga29071MálagaSpain Instituto de Energías Renovables Universidad de Castilla-La ManchaPaseo de La Investigación 102071AlbaceteSpain

A C/Ni composite was prepared via thermal decomposition of a nickel oleate complex at 700℃,yielding disperse Ni nanocrystals with an average size of 20 nm,encapsulated by carbon nanosheets as deduced from transmission electron microscopy(TEM)images and confirmed from X-ray photoelectron spectroscopy(XPS).Furthermore,the X-ray diffraction pattern revealed a good ordering of the carbon layers,forced by the Ni encapsulation to adopt a bending structure.Considering the close interaction between the graphitized framework and the metallic nanoparticles we have studied the properties of the composite as an anode for Li-ion batteries.Compared with other nanostructured synthetic carbons,this carbon composite has a low voltage hysteresis and a modest irreversible capacity value,properties that play a significant role in its behaviour as electrodes in full cell configuration.At moderate rate values,0.25 C,the electrode delivers an average capacity value around 723 mAh·g^−1 on cycling,among the highest values so far reported for this carbon type.At higher rate values,1 C,the average capacity values delivered by the cell on cycling decrease,around 205 mAh·g^−1,but it maintains good capacity retention,a coulombic efficiency close to 100%after the first cycles and recovery of the capacity values when the rate is restored from 3 to 0.1 C.

关键词： carbon nanosheets nickel nanoparticles anode lithium batteries

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