碳化钨/碳化二钨核壳结构纳米复合材料的制备及电催化活性  

Preparation and Electrocatalytic Activity of WC/W_2C Nanocomposite with Core-Shell Structure

作　　者：李国华[1,2] 陈丹[1] 郑翔[1] 谢伟淼[1] 程媛[1] 

机构地区：[1]浙江工业大学化学工程与材料学院,杭州310032 [2]浙江工业大学,绿色化学合成技术国家重点实验室培育基地,杭州310032

出　　处：《物理化学学报》2012年第9期2077-2083,共7页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(21173193)资助项目~~

摘　　要：以偏钨酸铵为钨源,铁黄(FeOOH)为载体,将表面包覆法与原位还原碳化技术相结合,制备出了具有核壳结构的碳化钨(WC)/碳化二钨(W2C)纳米复合材料;应用X射线衍射(XRD)分析、透射电子显微镜(TEM)和X射线能量散射谱(EDS)等手段对不同阶段样品的晶相、形貌、微结构和化学组成等特征进行了表征.结果表明:负载体经煅烧后,载体及包裹层的物相均发生了变化,形貌也相应地发生了改变;经盐酸处理及还原碳化后,样品由WC和W2C纳米颗粒组成,并构成了以W2C为壳,以WC为核的典型核壳结构;结合表征结果对核壳结构的形成机理进行了探讨.采用三电极体系循环伏安法测试了样品在酸性、中性和碱性溶液中对甲醇的电催化氧化活性.结果表明,与颗粒状碳化钨和介孔空心球状碳化钨相比,样品的电催化活性有了明显的提高.这说明W2C与WC构成核壳结构纳米复合材料后,其电化学性能有了明显的提升,核壳结构纳米复合材料是提高碳化钨催化材料活性的有效途径之一.A monotungsten carbide （WC）/bitungsten carbide （W2C） nanocomposite having a core-shell structure was prepared through a combination of surface coating and in situ reduction-carbonization, using ammonia meta-tungsten as tungsten source and iron oxide hydroxide as a hard support. The crystal phase, morphology, microstructure, and chemical components of the samples were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and X-ray energy dispersion spectroscopy （EDS）. The results show that after calcination, the morphology, the crystal phases of the support, and the coating layer around the support are changed. After acid dissolution, reduction, and carbonization, the crystal phase of the final product is composed of WC and W2C; the microstructure of the sample particle is a core-shell structure in which WC forms the core and W2C forms the shell. Based on the characterization results, the formation mechanism of the core-shell structure is discussed. The electrocatalytic activities of the samples for methanol electrooxidation were investigated by cyclic voltammetry with a three-electrode system in acidic, neutral, alkaline aqueous solutions. The results show that the electrocatalytic activity of the sample for methanol oxidation is higher than that of tungsten carbide particles and hollow microsphere tungsten carbide. These indicate that the electrocatalytic activity of tungsten carbide can be improved through the formation of core-shell structure, and it is one of the efficient ways to improve the electrocatalytic activity of tungsten carbide.

关 键 词：碳化钨 碳化二钨 纳米复合材料 核壳结构 电催化活性 

分 类 号：TB383.1[一般工业技术—材料科学与工程]