缺碳型介孔空心球状WC制备及其对甲醇氧化的电化学行为

采用喷雾干燥法制得空心球状结构偏钨酸铵, 通过固定床气固反应, 以CO/H₂为还原碳化气氛在700～900 ℃下制备了介孔结构空心球状碳化钨(WC). 经XRD, SEM及EDS测试表明, WC粉末样品在保持了单相WC的前提下, 样品存在一个微量缺碳的原子比例, 其W/C＞1, 且在高氢环境中WC球体表面有部分纳米颗粒依附于片状碳化钨基体上. 将制备得到的WC粉末样品制成微电极, 采用电化学测试技术研究了WC在硫酸介质中对甲醇的电催化氧化反应. 结果表明, 缺碳的介孔结构空心球状WC催化剂对甲醇氧化有着良好的电催化活性, 并对动力学参数进行了研究, 结果显示其反应的表观活化能为105.06 kJ/mol, 且其在微电极中的氧化行为受扩散控制.

Synthesis of Mesoporous Tungsten Carbide with Low Carbon Content and Its Electrocatalysis Toward Methanol Oxidation

The precursors ammonium metatungstate (AMT) microspheres were prepared by using an airflow spray drying method. Tungsten carbide (WC) samples were prepared by gas-solid reaction in the atmosphere of CO/H₂ in 700～900 ℃. XRD, SEM and EDS results showed that the samples were pure WC, with a ratio of W/C＞1. SEM images show that the structure of WC is hollow microsphere with nanoparticles around the surface. The WC was applied to a catalytic electrode for methanol electro-oxidation reaction by a PME (powder microelectrode) method. The results showed that the lower carbide content meso-WC-PME exhibited catalytic activity and stability in the methanol electro-oxidation, with the activation energy being 105.06 kJ/mol. The electrode reaction was controlled by liquid diffusion.