微波合成WC_x/MWCNTs及其电催化性能研究

Preparation of WC_x/MWCNTs by Microwave and Its Electrocatalytic Property

目的制备多壁碳纳米管负载碳化钨的纳米复合材料(WC_x/MWCNTs),探索微波加热温度对WC_x/MWCNTs合成的影响规律。方法利用分子自组装技术与微波加热技术相结合,以钨酸钠为W源,制备了WC_x/MWCNTs纳米复合材料。采用X射线衍射(XRD)和透射电子显微镜技术(TEM)对不同条件下制得样品的物相组成、结构及微观形貌进行了表征;采用循环伏安法在酸性环境下测试了WC_x/MWCNTs对氢和CH3OH的电催化性能。结果当微波加热温度为1000℃时,制备的WC_x/MWCNTs纳米复合材料由WC、WC2和C组成,碳纳米管的多壁结构保留较好,碳化钨颗粒均匀地分布在碳纳米管外表面,粒径为20~50 nm。循环伏安测试结果表明,制备的WC_x/MWCNTs在酸性环境下对氢具有一定的催化作用,但对甲醇没有明显的电催化作用。结论通过控制合理的微波加热温度,可制备出碳化钨粒径小、分布均匀、碳纳米管多壁结构完好的WC_x/MWCNTs纳米复合材料。制备的WC_x/MWCNTs在酸性环境下对氢具有一定的催化作用,可作为催化剂载体来负载其他金属制备复合催化剂。

The work aims to explore law of influence of microwave heating temperature on synthesis of WCx/MWCNTs by preparing tungsten carbide （WCx） nanoparticles supported on multiwalled carbon nanotubes （MWCNTs）. The WCx/MWCNTs nanocomposites were prepared with sodium tungstate as W source by combining molecular self-assembly technique and micro-wave heating technology. Phase composition, structure and morphology of the samples prepared under different conditions were characterized by X-ray diffractometer （XRD） and transmission electron microscopy （TEM）; electrochemical properties of WCx/MWCNTs to hydrogen and methyl alcohol were tested in acidic environment by cyclic voltammetry method. WCx/MWCNTs nanocomposites prepared at the microwave heating temperature of 1000 ℃ were composed of WC, WC2 and C phases. The multiwalled structures of carbon nanotubes were well preserved and the WC particles were evenly distributed on external surface of carbon nano tubes. Particle size of the carbon nanotubes was 20~50 nm. The cyclic voltammetry test results indicated that the prepared WCx/MWCNTs had a certain catalytic effect on hydrogen under acidic conditions, but it had no obvious electrocatalytic effect on methanol. WCx/MWCNTs nanocomposites with small particle size, uniform distribution and complete multiwalled structures of carbon nanotubes can be prepared by controlling the microwave heating temperature. The prepared WCx/MWCNTs nanocomposites have certain catalytic action on hydrogen under acidic conditions and can load other metals to prepare composite catalyst.